Journal of Composites Science

Editorial

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10 pages, 256 KiB

Open AccessEditorial

Characterization and Modelling of Composites, Volume III

by Stelios K. Georgantzinos

J. Compos. Sci. 2023, 7(11), 446; https://doi.org/10.3390/jcs7110446 - 27 Oct 2023

Cited by 1 | Viewed by 1894

Abstract

The realm of composite materials continues to evolve, with researchers pushing the boundaries of understanding and application. This Special Issue published in the Journal of Composites Science encapsulates the essence of these advancements, presenting a curated collection of research articles that highlight the [...] Read more.

The realm of composite materials continues to evolve, with researchers pushing the boundaries of understanding and application. This Special Issue published in the Journal of Composites Science encapsulates the essence of these advancements, presenting a curated collection of research articles that highlight the latest developments in the characterization and modelling of composites. The diversity of the covered topics ranges from a foundational understanding of composite behaviours to the application of cutting-edge modelling techniques. Each contribution offers a fresh perspective, expanding our knowledge of composites and setting the stage for future explorations in this dynamic domain. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

Research

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16 pages, 8305 KiB

Open AccessArticle

Preliminary Experimental and Numerical Study of the Tensile Behavior of a Composite Based on Sycamore Bark Fibers

by Helena Khoury Moussa, Philippe Lestriez, He Thong Bui, Pham The Nhan Nguyen, Philippe Michaud, Romain Lucas-Roper, Guy Antou, Viet Dung Luong, Pham Tuong Minh Duong, Fazilay Abbès and Boussad Abbès

J. Compos. Sci. 2024, 8(9), 333; https://doi.org/10.3390/jcs8090333 - 23 Aug 2024

Viewed by 654

Abstract

In the context of global sustainable development, using natural fibers as reinforcement for composites have become increasingly attractive due to their lightweight, abundant availability, renewability, and comparable specific properties to conventional fibers. This paper investigates the tensile properties of a sycamore bark fiber-reinforced [...] Read more.

In the context of global sustainable development, using natural fibers as reinforcement for composites have become increasingly attractive due to their lightweight, abundant availability, renewability, and comparable specific properties to conventional fibers. This paper investigates the tensile properties of a sycamore bark fiber-reinforced composite. The tensile tests using digital image correlation showed that, by adding 18% by volume of sycamore bark for the polyester matrix, the tensile modulus achieves 4788.4 ± 940.1 MPa. Moreover, the tensile strength of the polyester resin increased by approximately 90% when reinforced with sycamore bark fiber, achieving a tensile strength of 64.5 ± 13.4 MPa. These mechanical properties are determined by the way loads are transferred between the polyester matrix and fibers and by the strength of the bond between the fiber-matrix interfaces. Since it is difficult and time consuming to characterize the mechanical properties of natural fibers, an alternative approach was proposed in this study. The method consists of the identification of the fiber elastic modulus using a finite element analysis approach, based on tensile tests conducted on the sycamore bark fiber-reinforced composites. The model correctly describes the overall composite behavior, a good agreement is found between the experimental, and the finite element predicted stress–strain curves. The identified sycamore bark fiber elastic modulus is 17,763 ± 6051 MPa. These results show that sycamore bark fibers can be used as reinforcements to produce composite materials. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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17 pages, 3079 KiB

Open AccessArticle

Determining the Advanced Frequency of Composited Functionally Graded Material Plates Using Third-Order Shear Deformation Theory and Nonlinear Varied Shear Coefficients

by Chih-Chiang Hong

J. Compos. Sci. 2024, 8(8), 325; https://doi.org/10.3390/jcs8080325 - 16 Aug 2024

Viewed by 652

Abstract

The shear effect is usually considered in the numerical calculation of thick composited FGM plates. The characteristics that have the greatest effect on thickness are displacement type, shear correction coefficient, material property and temperature. For the advanced frequency study of thick composited functionally [...] Read more.

The shear effect is usually considered in the numerical calculation of thick composited FGM plates. The characteristics that have the greatest effect on thickness are displacement type, shear correction coefficient, material property and temperature. For the advanced frequency study of thick composited functionally graded material (FGM) plates, it is interesting to consider the extra effects of the nonlinear coefficient c₁ term of the third-order shear deformation theory (TSDT) of displacement on the calculation of varied shear correction coefficients. The values of nonlinear shear correction coefficients are usually functions of c₁, the power-law exponent parameter and environment temperature. Numerical frequency computations are calculated using a simple homogeneous equation, and are investigated using TSDT and the nonlinear shear correction coefficient for thick composited FGM plates. Results for natural frequencies are found via the functions of length-to-thickness ratio, the power-law exponent parameter, c₁ and environment temperature. This novel study in advanced frequency aims to determine the effects of the TSDT and nonlinear shear correction on thick FGM plates under free vibration. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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20 pages, 4718 KiB

Open AccessArticle

Buckling Analysis of Variable-Angle Tow Composite Plates through Variable Kinematics Hierarchical Models

by Gaetano Giunta, Domenico Andrea Iannotta, Levent Kirkayak and Marco Montemurro

J. Compos. Sci. 2024, 8(8), 320; https://doi.org/10.3390/jcs8080320 - 13 Aug 2024

Viewed by 823

Abstract

Variable-Angle Tow (VAT) laminates can improve straight fiber composites’ mechanical properties thanks to the application of curvilinear fibers. This characteristic allows one to achieve ambitious objectives for design and performance purposes. Nevertheless, the wider design space and the higher number of parameters result [...] Read more.

Variable-Angle Tow (VAT) laminates can improve straight fiber composites’ mechanical properties thanks to the application of curvilinear fibers. This characteristic allows one to achieve ambitious objectives for design and performance purposes. Nevertheless, the wider design space and the higher number of parameters result in a more complex structural problem. Among the various approaches that have been used for VAT study, Carrera’s Unified Formulation (CUF) allows one to obtain multiple theories within the same framework, guaranteeing a good compromise between the results’ accuracy and the computational cost. In this article, the linear buckling behavior of VAT laminates is analyzed through the extension of CUF 2D plate models within Reissner’s Mixed Variational Theorem (RMVT). The results show that RMVT can better approximate the prebuckling nonuniform stress field of the plate when compared to standard approaches, thus improving the prediction of the linear buckling loads of VAT composites. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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16 pages, 4709 KiB

Open AccessArticle

Compression after Impact Response of Kevlar Composites Plates

by Dionysis E. Mouzakis, Panagiotis J. Charitidis and Stefanos P. Zaoutsos

J. Compos. Sci. 2024, 8(8), 299; https://doi.org/10.3390/jcs8080299 - 1 Aug 2024

Viewed by 725

Abstract

Boeing and Airbus developed a special testing procedure to investigate the compressive response of laminates that have been impacted (following standards ASTM D 7137 and DIN 65561). This study focuses on both experimental and numerical analysis of Kevlar plates subjected to compression after [...] Read more.

Boeing and Airbus developed a special testing procedure to investigate the compressive response of laminates that have been impacted (following standards ASTM D 7137 and DIN 65561). This study focuses on both experimental and numerical analysis of Kevlar plates subjected to compression after impact. To ensure high quality and appropriate mechanical properties, the composite plates were manufactured using autoclaving. The DIN 65561 protocol was followed for all three test systems. Initially, ultrasonic C-scanning was performed on all plates before testing to confirm they were free of any significant defects arising from the manufacturing process. Subsequently, low-energy impact testing was conducted at levels ranging from 0 to 8 Joules. Three specimens were tested at each energy level. After the impact, all specimens underwent ultrasonic C-scanning again to assess the internal delamination damage caused by the impactor. Finally, both pristine and impacted specimens were subjected to compressive testing using the special jig specified in DIN 65561. The compressive impact strength results obtained from these tests were plotted against the delamination area measured by C-scanning. These data were then compared to the results obtained from specimens with artificial damage. Semi-empirical equations were used to fit both sets of curves. The same procedure (impact testing, C-scanning, and data analysis) was repeated to investigate the relationship between impact energy and total delamination area. Lastly, finite element modeling was employed to predict the buckling stresses that develop under compression in the impacted systems studied. These modeling approaches have demonstrated good accuracy in reproducing experimental results for CAI tests. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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27 pages, 11196 KiB

Open AccessArticle

Mechanical Characterization of GFRP Tiled Laminates for Structural Engineering Applications: Stiffness, Strength and Failure Mechanisms

by Jordi Uyttersprot, Wouter De Corte and Wim Van Paepegem

J. Compos. Sci. 2024, 8(7), 265; https://doi.org/10.3390/jcs8070265 - 8 Jul 2024

Viewed by 947

Abstract

This study investigates the mechanical properties of tiled laminates, frequently used in FRP bridges, and a completely new class of composites for which currently no experimental literature is available. In this paper, first a microscopic examination of laminates extracted from bridge deck flanges [...] Read more.

This study investigates the mechanical properties of tiled laminates, frequently used in FRP bridges, and a completely new class of composites for which currently no experimental literature is available. In this paper, first a microscopic examination of laminates extracted from bridge deck flanges is performed, revealing complex multi-ply structures and tiled laminates in the transverse direction of the bridge deck. The subsequent fabrication of tiled laminates in the transverse (i.e., weak) and longitudinal (i.e., strong) span direction explores stiffness and strength characteristics depending on the stacking angle. It is observed that the stiffness in both directions is only slightly reduced with increasing stacking angles, reaching a maximum decrease of 10%, while the failure strength is significantly reduced, particularly with longitudinal tiling, dropping by approximately 70% for a 2° stacking angle. Transverse tiling demonstrates a more moderate 45% strength reduction due to the presence of some 90° plies. Given the small reduction in the stiffness and the fact that in many applications the design is mainly governed by serviceability (i.e., stiffness) requirements than strength, this strength reduction may be acceptable, considering other advantages of the concept. Additionally, this research sheds light on failure mechanisms, emphasizing the role of ply assembly in stress distribution and highlighting the importance of gradual ply ends in reducing strain concentrations. These findings provide valuable insights for optimizing tiled laminates in structural applications, ensuring their effective and reliable use. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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11 pages, 5719 KiB

Open AccessArticle

Towards 3D Pore Structure of Porous Gypsum Cement Pozzolan Ternary Binder by Micro-Computed Tomography

by Girts Bumanis, Laura Vitola, Xiangming Zhou, Danutė Vaičiukynienė and Diana Bajare

J. Compos. Sci. 2024, 8(7), 264; https://doi.org/10.3390/jcs8070264 - 8 Jul 2024

Viewed by 776

Abstract

A sophisticated characterisation of a porous material structure has been challenging in material science. Three-dimensional (3D) structure analysis allows the evaluation of a material’s homogeneity, pore size distribution and pore wall properties. Micro-computed tomography (micro-CT) offers a non-destructive test method for material evaluation. [...] Read more.

A sophisticated characterisation of a porous material structure has been challenging in material science. Three-dimensional (3D) structure analysis allows the evaluation of a material’s homogeneity, pore size distribution and pore wall properties. Micro-computed tomography (micro-CT) offers a non-destructive test method for material evaluation. This paper characterises a novel ternary binder’s porous structure using micro-CT. Gypsum–cement–pozzolan (GCP) ternary binders are low-carbon footprint binders. Both natural and industrial gypsum were evaluated as a major components of GCP binders. Porous GCP binder was obtained by a foaming admixture, and the bulk density of the material characterised ranged from 387 to 700 kg/m³. Micro-CT results indicate that pores in the range from 0.017 to 3.0 mm can be effectively detected and described for porous GCP binders. The GCP binder structure proved to be dominant by 0.1 to 0.2 mm micropores. For GCP binders produced with natural gypsum, macropores from 2.2 to 2.9 mm are formed, while GCP binders with phosphogypsum possess pores from 0.2 to 0.6 mm. Micro-CT proved to be an effective instrument for characterising the homogeneity and hierarchical pore structure of porous ternary binders. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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11 pages, 2286 KiB

Open AccessArticle

Mechanical Properties and Thermal Conductivity of Y-Si and Gd-Si Silicides: First-Principles Calculations

by Kexue Peng, Panxin Huang, Guifang Han, Huan Liu, Weibin Zhang, Weili Wang and Jingde Zhang

J. Compos. Sci. 2024, 8(6), 221; https://doi.org/10.3390/jcs8060221 - 12 Jun 2024

Viewed by 679

Abstract

The traditional Si bonding layer in environmental barrier coatings has a low melting point (1414 °C), which is a significant challenge in meeting the requirements of the next generation higher thrust-to-weight ratio aero-engines. To seek new bonding layer materials with higher melting points, [...] Read more.

The traditional Si bonding layer in environmental barrier coatings has a low melting point (1414 °C), which is a significant challenge in meeting the requirements of the next generation higher thrust-to-weight ratio aero-engines. To seek new bonding layer materials with higher melting points, the mechanical properties of Y-Si and Gd-Si silicides were calculated by the first-principles method. Subsequently, empirical formulae were employed to compute the sound velocities, Debye temperatures, and the minimum coefficients of thermal conductivity for the YSi, Y₅Si₄, Y₅Si₃, GdSi, and Gd₅Si₄. The results showed that Y₅Si₄ has the best plasticity and ductility among all these materials. In addition, Gd₅Si₄ has the minimum Debye temperature (267 K) and thermal conductivity (0.43 W m⁻¹ K⁻¹) compared with others. The theoretical calculation results indicate that some silicides in the Y-Si and Gd-Si systems possess potential application value in high-temperature bonding layers for thermal and/or environmental barrier coating. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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16 pages, 7979 KiB

Open AccessArticle

Physical, Mechanical and Microstructural Characteristics of Perlite-Based Geopolymers Modified with Mineral Additives

by Natalia I. Kozhukhova, Roman A. Glazkov, Marina S. Ageeva, Marina I. Kozhukhova, Ivan S. Nikulin and Irina V. Zhernovskaya

J. Compos. Sci. 2024, 8(6), 211; https://doi.org/10.3390/jcs8060211 - 4 Jun 2024

Cited by 1 | Viewed by 879

Abstract

One of the promising raw materials for the synthesis of geopolymers is perlite, which is a natural low-calcium aluminosilicate. This research studied the physical, mechanical and microstructural characteristics of perlite-based geopolymers modified with different mineral additives that were prepared using different methods of [...] Read more.

One of the promising raw materials for the synthesis of geopolymers is perlite, which is a natural low-calcium aluminosilicate. This research studied the physical, mechanical and microstructural characteristics of perlite-based geopolymers modified with different mineral additives that were prepared using different methods of introducing the alkali components and curing conditions. The experimental results of the consolidated perlite-based geopolymer pastes showed that curing conditions and the method of introducing the alkali component into the geopolymer matrix had a minimal effect on the average density while demonstrating a significant boost in compressive strength. So, after thermal treatment, the compressive strength increased by 0.63 to 11.4 times for the mixes when fresh alkali solution was used and by 0.72 to 12.8 times for the mixes with the 24 h conditioned alkali solution. Maximum-strength spikes from 1.1 MPa to 13.2 MPa and from 0.7 MPa to 9.7 MPa were observed for the mixes with kaolin when prepared with fresh and conditioned alkali solutions, respectively. It was also observed that thermal treatment facilitates the compaction of the matrix structure by 18% and 1% for the non-modified mix and the mix modified with Portland cement. Perlite-based geopolymers modified with Portland cement and citrogypsum demonstrated a significant reduction in the initial and final setting times with both methods of introducing the alkali solution. On the surface of mixes modified with citrogypsum, regardless of the curing conditions and method of introducing the alkali component, an efflorescence substance was observed. The microstructural analysis of the consolidated geopolymer perlite-based pastes containing citrogypsum demonstrated a loose structure and the presence of efflorescence, which can be associated with a retardation in interaction processes between alkali cations and the aluminosilicate component. EDS analysis demonstrated that the presence of such elements as oxygen, sodium and sulfur may indicate the efflorescence of unreacted sodium hydroxide (NaOH), citrogypsum (CaSO₄) and the products of their interaction in the form of crystalline hydrates of sodium sulfate (Na₂SO₄). Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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26 pages, 5470 KiB

Open AccessArticle

Metaheuristic Optimization of Functionally Graded 2D and 3D Discrete Structures Using the Red Fox Algorithm

by J. S. D. Gaspar, M. A. R. Loja and J. I. Barbosa

J. Compos. Sci. 2024, 8(6), 205; https://doi.org/10.3390/jcs8060205 - 30 May 2024

Viewed by 592

Abstract

The growing applicability of functionally graded materials is justified by their ability to contribute to the development of advanced solutions characterized by the material customization, through the selection of the best parameters that will confer the best mechanical behaviour for a given structure [...] Read more.

The growing applicability of functionally graded materials is justified by their ability to contribute to the development of advanced solutions characterized by the material customization, through the selection of the best parameters that will confer the best mechanical behaviour for a given structure under specific operating conditions. The present work aims to attain the optimal design solutions for a set of illustrative 2D and 3D discrete structures built from functionally graded materials using the Red Fox Optimization Algorithm, where the design variables are material parameters. From the results achieved one concludes that the optimal selection and distribution of the different materials’ mixture and the different exponents associated with the volume fraction law significantly influence the optimal responses found. To note additionally the good performance of the coupling between this optimization technique and the finite element method used for the linear static and free vibration analyses. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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20 pages, 57487 KiB

Open AccessArticle

Impact Performance of 3D Orthogonal Woven Composites: A Finite Element Study on Structural Parameters

by Wang Xu, Mohammed Zikry and Abdel-Fattah M. Seyam

J. Compos. Sci. 2024, 8(6), 193; https://doi.org/10.3390/jcs8060193 - 21 May 2024

Cited by 1 | Viewed by 848

Abstract

This study uses the finite element method (FEM) to investigate the effect of key structural parameters on the impact resistance of E-glass 3D orthogonal woven (3DOW) composites subjected to low-velocity impact. These structural parameters include the number of y-yarn layers, the path of [...] Read more.

This study uses the finite element method (FEM) to investigate the effect of key structural parameters on the impact resistance of E-glass 3D orthogonal woven (3DOW) composites subjected to low-velocity impact. These structural parameters include the number of y-yarn layers, the path of the binder yarn (z-yarn), and the density of the x-yarn. Using ABAQUS, yarn-level finite element (FE) models are created based on the measured geometrical parameters and validated for energy absorption and damage behavior from experimental data gathered from the previous study. The results from finite element analysis (FEA) indicate that the x-yarn density and the binder path substantially influenced the composites’ damage behavior and impact performance. Increasing x-yarn density in 3DOW leads to a 15% increase in energy absorption compared to models with reduced x-yarn densities. Moreover, as the x-yarn density increases, crack lengths at the back face of the resin matrix decrease in the y-yarn direction but increase in the x-yarn direction. The basket weave structure absorbs less energy than plain and 2 × 1 twill structures due to the less constrained weft primary yarns. These results underscore the importance of these structural parameters in optimizing 3DOW composite for better impact performance, providing valuable insights for the design of advanced composite structures. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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17 pages, 52966 KiB

Open AccessArticle

Mechanical Analysis and Simulation of Wood Textile Composites

by Claudia L. von Boyneburgk, Dimitri Oikonomou, Werner Seim and Hans-Peter Heim

J. Compos. Sci. 2024, 8(5), 190; https://doi.org/10.3390/jcs8050190 - 18 May 2024

Viewed by 834

Abstract

Wood Textile Composites (WTCs) represent a new and innovative class of materials in the field of natural fiber composites. Consisting of fabrics made from willow wood strips (Salix americana) and polypropylene (PP), this material appears to be particularly suitable for structural [...] Read more.

Wood Textile Composites (WTCs) represent a new and innovative class of materials in the field of natural fiber composites. Consisting of fabrics made from willow wood strips (Salix americana) and polypropylene (PP), this material appears to be particularly suitable for structural applications in lightweight construction. Since the threads of the fabric are significantly oversized compared to classic carbon or glass rovings, fundamental knowledge of the mechanical properties of the material is required. The aim of this study was to investigate whether WTCs exhibit classic behavior in terms of fiber composite theory and to classify them in relation to comparable composite materials. It was shown that WTCs meet all the necessary conditions for fiber-reinforced composites in tensile, bending, and compression tests and can be classified as natural-fiber-reinforced polypropylene composites. In addition, it was investigated whether delamination between the fiber and matrix can be simulated by using experimentally determined mechanical data as input. Using finite element analysis (FEA), it was shown that the shear stress components of a stress tensor in the area of the interface between the fiber and matrix are responsible for delamination in the composite material. It was also shown that the resistance to shear stress depends on the geometric conditions of the reinforcing fabric. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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14 pages, 1697 KiB

Open AccessArticle

Analysis of Intact/Delaminated Composite and Sandwich Beams Using a Higher-Order Modeling Technique

by Yuan Feng, Abdul Hamid Sheikh and Guanzhen Li

J. Compos. Sci. 2024, 8(5), 175; https://doi.org/10.3390/jcs8050175 - 10 May 2024

Cited by 1 | Viewed by 889

Abstract

A simple higher-order model (HOM) is presented in this study for the bending analysis of an intact or delaminated composite and sandwich beam. This model adopts the concept of sub-laminates to simulate multilayered structures, and each sub-laminate takes cubic variation for axial displacement [...] Read more.

A simple higher-order model (HOM) is presented in this study for the bending analysis of an intact or delaminated composite and sandwich beam. This model adopts the concept of sub-laminates to simulate multilayered structures, and each sub-laminate takes cubic variation for axial displacement and linear variation for transverse displacement through the thickness. A sub-laminate possesses displacement components at its surfaces (bottom and top) that provide a straightforward way to improve the accuracy of prediction by stacking several sub-laminates. Thus, analysts will have the flexibility to balance the computational cost and the accuracy by selecting an appropriate sub-lamination scheme. The proposed model was implemented by developing a C⁰ beam element that has only displacement unknowns. The model was used to solve numerical examples of composite and sandwich beams to demonstrate its performance. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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12 pages, 8727 KiB

Open AccessCommunication

Comprehensive Composite Mould Filling Pattern Dataset for Process Modelling and Prediction

by Boon Xian Chai, Jinze Wang, Thanh Kim Mai Dang, Mostafa Nikzad, Boris Eisenbart and Bronwyn Fox

J. Compos. Sci. 2024, 8(4), 153; https://doi.org/10.3390/jcs8040153 - 18 Apr 2024

Cited by 11 | Viewed by 1314

Abstract

The Resin Transfer Moulding process receives great attention from both academia and industry, owing to its superior manufacturing rate and product quality. Particularly, the progression of its mould filling stage is crucial to ensure a complete reinforcement saturation. Contemporary process simulation methods focus [...] Read more.

The Resin Transfer Moulding process receives great attention from both academia and industry, owing to its superior manufacturing rate and product quality. Particularly, the progression of its mould filling stage is crucial to ensure a complete reinforcement saturation. Contemporary process simulation methods focus primarily on physics-based approaches to model the complex resin permeation phenomenon, which are computationally expensive to solve. Thus, the application of machine learning and data-driven modelling approaches is of great interest to minimise the cost of process simulation. In this study, a comprehensive dataset consisting of mould filling patterns of the Resin Transfer Moulding process at different injection locations for a composite dashboard panel case study is presented. The problem description and significance of the dataset are outlined. The distribution of this comprehensive dataset aims to lower the barriers to entry for researching machine learning approaches in composite moulding applications, while concurrently providing a standardised baseline for evaluating newly developed algorithms and models in future research works. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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11 pages, 2944 KiB

Open AccessArticle

The Morphological and Thermal Characteristics of Hollow-Glass-Microsphere-Coated Phase Change Material–Cow Pie Embedded Recycled Plastic Tiles for Cool Roofs

by S. Krishna Satya and P. S. Rama Sreekanth

J. Compos. Sci. 2024, 8(4), 148; https://doi.org/10.3390/jcs8040148 - 13 Apr 2024

Viewed by 1545

Abstract

This study addresses the global plastic waste crisis and the urban heat island effect by developing an innovative solution: recycled plastic roof tiles embedded with phase change material (PCM) and coated with hollow-glass-microsphere-based white paint. The samples were fabricated with cow pie fibers, [...] Read more.

This study addresses the global plastic waste crisis and the urban heat island effect by developing an innovative solution: recycled plastic roof tiles embedded with phase change material (PCM) and coated with hollow-glass-microsphere-based white paint. The samples were fabricated with cow pie fibers, OM37 and OM42 PCM materials with different wt./vol. values, i.e., 15/50, 20/50, 25/50, 30/50 ratios. The fabricated tiles were coated with hollow glass microspheres to provide a reflective layer. The tiles’ effectiveness was evaluated through morphological examination and thermal analysis. The SEM analysis revealed an excellent bonding ability for the PCM blend, i.e., OM37 and OM42 at a 20/50 ratio (wt./vol.) with cow pie fibers. Adding cow pie fibers to the PCM shifted the melting points of OM37 and OM42, indicating an increased heat storage capacity in both blends. The thermal conductivity results revealed decreased thermal conductivity with an increased cow pie fiber percentage. The recycled plastic roof tile of the PCM composite at a 20/50 (wt./vol.) ratio showed good thermal properties. Upon testing in real-time conditions in a physical setup, the roof tiles showed a temperature reduction of 8 °C from outdoors to indoors during the peak of summer. In winter, cozy temperatures were maintained indoors due to the heat regulation from the roof. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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17 pages, 8050 KiB

Open AccessArticle

A Numerical Assessment of the Influence of Local Stress Ratio in the Fatigue Analysis of Post-Buckled Composite Single-Stringer Specimen

by Antonio Raimondo and Chiara Bisagni

J. Compos. Sci. 2024, 8(4), 143; https://doi.org/10.3390/jcs8040143 - 11 Apr 2024

Viewed by 1363

Abstract

This paper presents a numerical approach for investigating fatigue delamination propagation in composite stiffened panels loaded in compression in the post-buckling field. These components are widely utilized in aerospace structures due to their lightweight and high-strength properties. However, fatigue-induced damage, particularly delamination at [...] Read more.

This paper presents a numerical approach for investigating fatigue delamination propagation in composite stiffened panels loaded in compression in the post-buckling field. These components are widely utilized in aerospace structures due to their lightweight and high-strength properties. However, fatigue-induced damage, particularly delamination at the skin–stringer interface, poses a significant challenge. The proposed numerical approach, called the “Min–Max Load Approach”, allows for the calculation of the local stress ratio in a single finite element analysis. It represents the ratio between the minimum and maximum values of the stress along the delamination front, enabling accurate evaluation of the crack growth rate. The methodology is applied here in conjunction with the cohesive zone model technique to evaluate the post-buckling fatigue behavior of a composite single-stringer specimen with an initial delamination. Comparisons with experimental data validate the predictive capabilities of the proposed approach. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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16 pages, 3571 KiB

Open AccessArticle

Numerical Investigation on the Capability of Modeling Approaches for Composite Cylinders under Low-Velocity Impact Loading

by Shiva Rezaei Akbarieh, Dayou Ma, Claudio Sbarufatti and Andrea Manes

J. Compos. Sci. 2024, 8(4), 141; https://doi.org/10.3390/jcs8040141 - 10 Apr 2024

Viewed by 1219

Abstract

Composite pressure vessels can be exposed to extreme loadings, for instance, impact loading, during manufacturing, maintenance, or their service lifetime. These kinds of loadings may provoke both visible and invisible levels of damage, e.g., fiber breakage matrix cracks and delamination and eventually may [...] Read more.

Composite pressure vessels can be exposed to extreme loadings, for instance, impact loading, during manufacturing, maintenance, or their service lifetime. These kinds of loadings may provoke both visible and invisible levels of damage, e.g., fiber breakage matrix cracks and delamination and eventually may lead to catastrophic failures. Thus, the quantification and evaluation of such damages are of great importance. Considering the cost of relevant full-scale experiments, a numerical model can be a powerful tool for such a kind of study. This paper aims to provide a numerical study to investigate the capability of different modeling methods to predict delamination in composite vessels. In this study, various numerical modeling aspects, such as element types (solid and shell elements) and material parameters (such as interface properties), were considered to investigate delamination in a composite pressure vessel under low-velocity impact loading. Specifically, solid elements were used to model each layer of the composite pressure vessel, while, in another model, shell elements with composite layup were considered. Compared with the available experimental data from low-velocity impact tests described in the literature, the capability of these two models to predict both mechanical responses and failure phenomena is shown. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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22 pages, 11714 KiB

Open AccessArticle

Dynamic Behavior and Permanent Indentation in S2-Glass Woven Fabric Reinforced Polymer Composites under Impact: Experimentation and High-Fidelity Modeling

by Mohammad Rezasefat, Yogesh Kumar, Amanda Albertin Xavier da Silva, Sandro Campos Amico, James David Hogan and Andrea Manes

J. Compos. Sci. 2024, 8(4), 138; https://doi.org/10.3390/jcs8040138 - 9 Apr 2024

Viewed by 1198

Abstract

This paper studies the behavior of S2-glass woven fabric reinforced polymer composite under low-velocity impact at 18–110 J energy. A macro-homogeneous finite element model for the prediction of their response is implemented, considering the non-linear material behavior and intralaminar and interlaminar failure modes [...] Read more.

This paper studies the behavior of S2-glass woven fabric reinforced polymer composite under low-velocity impact at 18–110 J energy. A macro-homogeneous finite element model for the prediction of their response is implemented, considering the non-linear material behavior and intralaminar and interlaminar failure modes for the prediction of impact damage. The model accurately predicted the permanent indentation caused by impact. By applying the Ramberg-Osgood formulation, different initial stiffness values are examined to assess the post-impact unloading response. This approach reveals the significant role of initial stiffness in inelastic strain accumulation and its consequent effect on permanent indentation depth. A higher initial stiffness correlates with increased inelastic strain, influencing the impactor rebound and resulting in greater permanent indentation. By accurately predicting permanent indentation, and damage accumulation for different impact energies, this study contributes to a better understanding of the impact behavior of composite materials, thereby promoting their wider application. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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13 pages, 2189 KiB

Open AccessArticle

Mechanical and Thermal Properties of the Hf–Si System: First-Principles Calculations

by Panxin Huang, Guifang Han, Huan Liu, Weibin Zhang, Kexue Peng, Jianzhang Li, Weili Wang and Jingde Zhang

J. Compos. Sci. 2024, 8(4), 129; https://doi.org/10.3390/jcs8040129 - 2 Apr 2024

Viewed by 1257

Abstract

The relatively low melting point of a traditional Si bonding layer limits the upper servicing temperature of environmental barrier coatings (EBC). To explore suitable high temperature bonding layers and expedite the development of EBC, first-principles calculation was used to evaluate the mechanical properties [...] Read more.

The relatively low melting point of a traditional Si bonding layer limits the upper servicing temperature of environmental barrier coatings (EBC). To explore suitable high temperature bonding layers and expedite the development of EBC, first-principles calculation was used to evaluate the mechanical properties and thermal conductivity of HfSi₂, HfSi, Hf₅Si₄, Hf₃Si₂, and Hf₂Si with much higher melting points than that of Si. Among them, HfSi₂ has the lowest modulus capable of good modulus matching with SiC substrate. In addition, these Hf-Si compounds have much lower high temperature thermal conductivity with Hf₂Si being the lowest of 0.63 W m⁻¹ K⁻¹, which is only half of Si, capable of improved heat insulation. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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20 pages, 17545 KiB

Open AccessArticle

Impact Characteristics and Repair Approaches of Distinct Bio-Based Matrix Composites: A Comparative Analysis

by Bharath Ravindran, Timotheos Agathocleous, Beate Oswald-Tranta, Ewald Fauster and Michael Feuchter

J. Compos. Sci. 2024, 8(4), 126; https://doi.org/10.3390/jcs8040126 - 29 Mar 2024

Viewed by 1537

Abstract

Increasing global concerns regarding environmental issues have driven significant advancements in the development of bio-based fiber reinforced polymer composites. Despite extensive research on bio-composites, there remains a noticeable gap in studies specifically addressing the challenges of repairing bio-composites for circular economy adoption. Traditional [...] Read more.

Increasing global concerns regarding environmental issues have driven significant advancements in the development of bio-based fiber reinforced polymer composites. Despite extensive research on bio-composites, there remains a noticeable gap in studies specifically addressing the challenges of repairing bio-composites for circular economy adoption. Traditional repair techniques for impacted composites, such as patching or scarf methods, are not only time-consuming but also require highly skilled personnel. This paper aims to highlight cost-effective repair strategies for the restoration of damaged composites, featuring flax fiber as the primary reinforcement material and distinct matrix systems, namely bio-based epoxy and bio-based vitrimer matrix. Glass fiber was used as a secondary material to validate the bio-based vitrimer matrix. The damage caused specifically by low impact is detrimental to the structural integrity of the composites. Therefore, the impact resistance of the two composite materials is evaluated using instrumented drop tower tests at various energy levels, while thermography observations are employed to assess damage evolution. Two distinct repair approaches were studied: the resin infiltration repair method, employing bio-based epoxy, and the reconsolidation (self-healing) repair method, utilizing the bio-based vitrimer matrix. The efficiency of these repair methods was assessed through active thermography and compression after impact tests. The repair outcomes demonstrate successful restoration and the maintenance of ultimate strength at an efficiency of 90% for the re-infiltration repair method and 92% for the reconsolidation repair method. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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28 pages, 26981 KiB

Open AccessArticle

Micro- and Macro-Scale Topology Optimization of Multi-Material Functionally Graded Lattice Structures

by Jerónimo Santos, Abdolrasoul Sohouli and Afzal Suleman

J. Compos. Sci. 2024, 8(4), 124; https://doi.org/10.3390/jcs8040124 - 28 Mar 2024

Cited by 2 | Viewed by 1472

Abstract

Lattice structures are becoming an increasingly attractive design approach for the most diverse engineering applications. This increase in popularity is mainly due to their high specific strength and stiffness, considerable heat dissipation, and relatively light weight, among many other advantages. Additive manufacturing techniques [...] Read more.

Lattice structures are becoming an increasingly attractive design approach for the most diverse engineering applications. This increase in popularity is mainly due to their high specific strength and stiffness, considerable heat dissipation, and relatively light weight, among many other advantages. Additive manufacturing techniques have made it possible to achieve greater flexibility and resolution, enabling more complex and better-performing lattice structures. Unrestricted material unit cell designs are often associated with high computational power and connectivity problems, and highly restricted lattice unit cell designs may not reach the optimal desired properties despite their lower computational cost. This work focuses on increasing the flexibility of a restricted unit cell design while achieving a lower computational cost. It is based on a two-scale concurrent optimization of the lattice structure, which involves simultaneously optimizing the topology at both the macro- and micro-scales to achieve an optimal topology. To ensure a continuous optimization approach, surrogate models are used to define material and geometrical properties. The elasticity tensors for a lattice unit cell are obtained using an energy-based homogenization method combined with voxelization. A multi-variable parameterization of the material unit cell is defined to allow for the synthesis of functionally graded lattice structures. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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17 pages, 12134 KiB

Open AccessArticle

Mitigating Crack Propagation in Hybrid Composites: An Experimental and Computational Study

by Suma Ayyagari and Marwan Al-Haik

J. Compos. Sci. 2024, 8(4), 122; https://doi.org/10.3390/jcs8040122 - 27 Mar 2024

Viewed by 1356

Abstract

The exceptional properties of carbon nanotubes (CNTs) make them ideal nanofillers for various composite materials. In carbon fiber-reinforced polymer (CFRP) composites. CNTs can be grown on the carbon fiber surface to act as a third interface between the fiber and the matrix. However, [...] Read more.

The exceptional properties of carbon nanotubes (CNTs) make them ideal nanofillers for various composite materials. In carbon fiber-reinforced polymer (CFRP) composites. CNTs can be grown on the carbon fiber surface to act as a third interface between the fiber and the matrix. However, it was established that the uncontrolled random growth of CNTs could exacerbate delamination in composite structures. Thick nanofiller films could hinder the epoxy from seeping into the carbon fiber, resulting in insufficient interlaminar strength. Hence, the density and distribution of nanofillers play a crucial role in determining the hybrid composite fracture mechanisms. In this investigation, CNTs were grown using the low-temperature technique into specific patterns over carbon fibers to discern their derived composites’ fracture properties. The composite fracture energy release was probed using a double cantilever beam (DCB) test setup and digital image correlation (DIC) to monitor interlaminar crack propagation. A standard finite element simulation model based on the cohesive zone method (CZM) was also utilized to delineate fracture behaviors of the various composite configurations. Results conclude that a coarser pattern of CNT growth enhances resistance to crack propagation, thus improving the interlaminar fracture toughness of a composite structure. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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13 pages, 4060 KiB

Open AccessArticle

Optimization of a Tapered Specimen Geometry for Short-Term Dynamic Tensile Testing of Continuous Fiber Reinforced Thermoplastics

by Florian Mischo and Sebastian Schmeer

J. Compos. Sci. 2024, 8(3), 93; https://doi.org/10.3390/jcs8030093 - 3 Mar 2024

Cited by 1 | Viewed by 1309

Abstract

Continuous fiber reinforced thermoplastics (cFRTP) are one of the most promising lightweight materials. For their use in structural components, reproducible and comparable material values have to be evaluated, especially at high strain rates. Due to their high stiffness and outstanding strength properties, the [...] Read more.

Continuous fiber reinforced thermoplastics (cFRTP) are one of the most promising lightweight materials. For their use in structural components, reproducible and comparable material values have to be evaluated, especially at high strain rates. Due to their high stiffness and outstanding strength properties, the evaluation of the material behavior at high strain rates is complex. In the presented work, a new tensile specimen geometry for strain rate testing is virtually optimized using a metamodel approach with an artificial neural network. The final specimen design is experimentally validated and compared with rectangular specimen results for a carbon fiber reinforced polycarbonate (CF-PC). The optimized specimen geometry leads to 100% valid test results in experimental validation of cross-ply laminates and reaches 9% higher tensile strength values than the rectangle geometry with applied end tabs at a strain rate of 40 s⁻¹. Through the optimization, comparable material parameters can be efficiently generated for a successful cFRTP strain rate characterization. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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17 pages, 3297 KiB

Open AccessArticle

Experimental Comparative Analysis of the Through-Thickness and In-Plane Compression Moduli of Unidirectional CFRP Laminates

by Raffael Bogenfeld

J. Compos. Sci. 2024, 8(2), 76; https://doi.org/10.3390/jcs8020076 - 13 Feb 2024

Cited by 1 | Viewed by 1527

Abstract

This study explores the experimental characterization of the through-thickness compression properties in unidirectional laminates using cube compression tests. Cubical specimens, each with an edge length of

10

mm, were symmetrically outfitted with biaxial strain gauges and subjected to a compression test. While similar [...] Read more.

This study explores the experimental characterization of the through-thickness compression properties in unidirectional laminates using cube compression tests. Cubical specimens, each with an edge length of

10

mm, were symmetrically outfitted with biaxial strain gauges and subjected to a compression test. While similar methodologies exist in the literature, this work primarily addresses the potential biases inherent in the testing procedure and their mitigation. The influence of friction-induced non-uniform deformation behavior is compensated through a scaling of the stiffness measurements using finite element (FE) analysis results. This scaling significantly enhances the accuracy of the resulting parameters of the experiments. The ultimate failure of the specimens, originating from stress concentrations at the edges, resulted in fracture angles ranging between

60 °

and

67 °

. Such fracture patterns, consistent with findings from other researchers, are attributed to shear stress induced by friction at the load introduction faces. The key findings of this research are the comparisons between the through-thickness modulus (

E_{33 c}

) and strength (

X_{33 c}

) and their in-plane counterparts (

E_{22 c}

and

X_{22 c}

). The results indicate deteriorations of

E_{33 c}

and

X_{33 c}

from

E_{22 c}

and

X_{22 c}

by margins of

5

% and

7

%, respectively. Furthermore, the results for

E_{22 c}

and

X_{22 c}

were compared with the results obtained through a standard test, revealing a

12

% enhancement in strength

X_{22 c}

and

4

% underestimated stiffness

E_{22 c}

in the cube compression test. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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14 pages, 9975 KiB

Open AccessArticle

Development of a Novel Lightweight Utility Pole Using a New Hybrid Reinforced Composite—Part 2: Numerical Simulation and Design Procedure

by Qianjiang Wu and Farid Taheri

J. Compos. Sci. 2024, 8(2), 50; https://doi.org/10.3390/jcs8020050 - 30 Jan 2024

Viewed by 1442

Abstract

The first paper of this two-part series discussed the development of a novel lightweight 3D wood dowel-reinforced glass epoxy hybrid composite material (3DdrFRP) and its manufacturing procedures. It also experimentally compared the performance of scaled utility poles made from conventional 2D E-glass epoxy [...] Read more.

The first paper of this two-part series discussed the development of a novel lightweight 3D wood dowel-reinforced glass epoxy hybrid composite material (3DdrFRP) and its manufacturing procedures. It also experimentally compared the performance of scaled utility poles made from conventional 2D E-glass epoxy and 3DdrFRP materials. In the second part, the development of robust, efficient, and fairly accurate nonlinear finite element (FE) models is outlined. The models are calibrated based on experimental results and used to simulate the performance of equivalent 2D and 3D poles, proving the integrity of the numerical models. Additionally, a simplified analytical calculation method is developed for practicing engineers to evaluate the stiffness of 3D-DrFRP poles fairly accurately and quickly. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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12 pages, 5834 KiB

Open AccessArticle

Characterization of Interlaminar Friction during the Forming Processes of High-Performance Thermoplastic Composites

by Daniel Campos, Pere Maimí and Alberto Martín

J. Compos. Sci. 2024, 8(2), 38; https://doi.org/10.3390/jcs8020038 - 23 Jan 2024

Cited by 1 | Viewed by 1750

Abstract

Friction is a pivotal factor influencing wrinkle formation in composite material shaping processes, particularly in novel thermoplastic composites like polyetheretherketone (PEEK) and low-melting polyaryletherketone (LM-PAEK) matrices reinforced with unidirectional carbon fibers. The aerospace sector lacks comprehensive data on the behavior of these materials [...] Read more.

Friction is a pivotal factor influencing wrinkle formation in composite material shaping processes, particularly in novel thermoplastic composites like polyetheretherketone (PEEK) and low-melting polyaryletherketone (LM-PAEK) matrices reinforced with unidirectional carbon fibers. The aerospace sector lacks comprehensive data on the behavior of these materials under forming conditions, motivating this study’s objective to characterize the interlaminar friction of such high-performance thermoplastic composites across diverse temperatures and forming parameters. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were employed to analyze the thermomechanical behaviors of PEEK and LM-PAEK. These data guided friction tests covering room-to-forming temperatures. Horizontal pull-out fixed-plies tests were conducted to determine the friction coefficient and shear stress dependency concerning temperature, pressure, and pulling rate. Below the melting point, both materials adhered to Coulomb’s law for friction behavior. However, above the melting temperature, PEEK’s friction decreased while LM-PAEK’s friction increased with rising temperatures. These findings highlight the distinct responses of these materials to temperature variations, pulling rates, and pressures, emphasizing the need for further research on friction characterization around glass transition and melting temperatures to enhance our understanding of this phenomenon. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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20 pages, 10998 KiB

Open AccessArticle

The Behavior of Banyan (B)/Banana (Ba) Fibers Reinforced Hybrid Composites Influenced by Chemical Treatment on Tensile, Bending and Water Absorption Behavior: An Experimental and FEA Investigation

by Prabhakar C. G, M Sreenivas Reddy, Shashanka Rajendrachari, Rayappa Shrinivas Mahale, V. Mahesh and Anup Pandith

J. Compos. Sci. 2024, 8(1), 31; https://doi.org/10.3390/jcs8010031 - 13 Jan 2024

Cited by 1 | Viewed by 1686

Abstract

Natural fiber-based composites are highly prioritized in present industries due to their properties and benefits over synthetic fibers. Due to their biodegradable nature, banyan and banana fibers were used for the present work. This paper deals with an experimental and FEA investigation of [...] Read more.

Natural fiber-based composites are highly prioritized in present industries due to their properties and benefits over synthetic fibers. Due to their biodegradable nature, banyan and banana fibers were used for the present work. This paper deals with an experimental and FEA investigation of the tensile and bending behavior of banyan (B) and banana (Ba)-reinforced composites with different volume fractions, such as 25B/25Ba, 30B/20Ba, and 35B/15Ba, with a 50% weight fraction of epoxy resin and different fiber orientations. The hybrid composites treated with a 5% NaOH solution have better results as compared to untreated hybrid composites, with a volume fraction of 30% banyan fibers and 20% banana fiber (30B/20Ba), giving greater tensile and flexural properties for both treated and untreated fiber composites when compared to other volume fraction composites at 0/0/0/0 orientation. The maximum tensile and bending strength was found in the 30B/20Ba volume fractions to be 63.37 MPa and 67.07 MPa, respectively. For treated fiber composites, water absorption increases with an increase in the duration of immersion in composites up to 144 h. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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16 pages, 2795 KiB

Open AccessArticle

Prediction of the Bond Strength of Externally Bonded FRP Sheets Applied to Concrete via Grooves Technique Using Artificial Neural Networks

by Abdelatif Salmi

J. Compos. Sci. 2024, 8(1), 30; https://doi.org/10.3390/jcs8010030 - 12 Jan 2024

Cited by 2 | Viewed by 1778

Abstract

The present study aims to fill a gap in the literature on the estimation of the bond strength of fiber reinforced polymer sheets bonded to concrete, via the externally bonded reinforcement on grooves (EBROG) technique, employing the curve-fitting on existing datasets in the [...] Read more.

The present study aims to fill a gap in the literature on the estimation of the bond strength of fiber reinforced polymer sheets bonded to concrete, via the externally bonded reinforcement on grooves (EBROG) technique, employing the curve-fitting on existing datasets in the literature and the methodology of Artificial Neural Networks (ANNs). Therefore, a dataset of 39 experimental results derived from EBROG technique is collected from the literature. A mathematical equation for the bond strength of FRP sheets applied on concrete via the EBROG technique was suggested using curve-fitting and general regression. The proposed mathematical equation is compared and validated with experimental results. The developed ANN model was constructed after testing diverse hidden layers and neurons to find the optimal predictions. The validation of the model is carried out using the experimental results and a statistical analysis is applied to assess the proposed mathematical equation and the proposed ANN model. Furthermore, a parametric study using the ANN model was also performed to investigate the influence of various factors on the bond strength of FRP sheets bonded to concrete. The parametric study proves that the bond strength increases with increasing the tensile stiffness per width, the FRP sheet width, and the concrete compressive strength; however, the effect of the Groove’s width and depth is found to be not monotonous. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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13 pages, 10066 KiB

Open AccessArticle

Development and Characterization of Flax–Gypsum Composites

by Vamsi Chakarala, Jens Schuster and Yousuf Pasha Shaik

J. Compos. Sci. 2024, 8(1), 27; https://doi.org/10.3390/jcs8010027 - 11 Jan 2024

Cited by 1 | Viewed by 1803

Abstract

Flax–gypsum composites are an emerging class of environmentally friendly materials that combine the mechanical properties of gypsum with the advantageous characteristics of flax fibers. The production of flax–gypsum composites involve the incorporation of flax fibers, derived from the flax plant, into gypsum matrix [...] Read more.

Flax–gypsum composites are an emerging class of environmentally friendly materials that combine the mechanical properties of gypsum with the advantageous characteristics of flax fibers. The production of flax–gypsum composites involve the incorporation of flax fibers, derived from the flax plant, into gypsum matrix systems. In order to create a uniform distribution of fibers within the gypsum matrix, the hand lay-up approach has been used to produce the specimens. The fiber content and orientation significantly influence the resulting mechanical and physical properties of the composites. Various tests were conducted on the samples, such as a flexural test, a compression test, a density test, a water absorption test, and a microscopy test. The addition of flax fibers imparts several desirable properties to the gypsum matrix. When combined with gypsum, these fibers enhanced the composite’s mechanical properties, such as flexural strength and compressive strength. The results indicated improved compression and flexural strengths due to effective load transfer within the matrix, for up to 10% of fiber loading. A decrease in composite density upon flax fiber addition results in a lighter material, enabling insights for various applications. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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16 pages, 14588 KiB

Open AccessArticle

Quasi-Static Fracture Toughness and Damage Monitoring in Liquid Metal Reinforced Hybrid Composites

by Zachary Safford, Mohammed Shonar and Vijaya Chalivendra

J. Compos. Sci. 2024, 8(1), 25; https://doi.org/10.3390/jcs8010025 - 11 Jan 2024

Cited by 1 | Viewed by 1588

Abstract

An experimental study is performed to investigate the quasi-static fracture toughness and damage monitoring capabilities of liquid metal (75.5% Gallium/24.5% Indium) reinforced intraply glass/carbon hybrid composites. Two different layups (G-0, where glass fibers are along the crack propagation direction; C-0, where carbon fibers [...] Read more.

An experimental study is performed to investigate the quasi-static fracture toughness and damage monitoring capabilities of liquid metal (75.5% Gallium/24.5% Indium) reinforced intraply glass/carbon hybrid composites. Two different layups (G-0, where glass fibers are along the crack propagation direction; C-0, where carbon fibers are along the crack propagation direction) and two different weight percentages of liquid metal (1% and 2%) are considered in the fabrication of the composites. A novel four-probe technique is employed to determine the piezo-resistive damage response under mode-I fracture loading conditions. The effect of layups and liquid metal concentrations on fracture toughness and changes in piezo-resistance response is discussed. The C-composite without liquid metal demonstrated higher fracture toughness compared to that of the G-composite due to carbon fiber breakage. The addition of liquid metal decreases the fracture initiation toughness of both G- and C-composites. Scanning electron microscopy images show that liquid metal takes the form of large liquid metal pockets and small spherical droplets on the fracture surfaces. In both C- and G-composites, the peak resistance change of composites with 2% liquid metal is substantially lower than that of both no-liquid metal and 1% liquid metal composites. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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14 pages, 3920 KiB

Open AccessArticle

Finite Element Modelling of the Effect of Adhesive Z-Connections on the Swelling of a Laminated Wood Composite

by Mohammad Sadegh Mazloomi, Wenchang He and Philip David Evans

J. Compos. Sci. 2023, 7(10), 442; https://doi.org/10.3390/jcs7100442 - 18 Oct 2023

Cited by 1 | Viewed by 1588

Abstract

This study used finite element analysis (FEA) to model the effects of adhesive Z-connections on the thickness swelling of laminated wood composites exposed to water. We hypothesized that the area density, diameter, and spatial distribution of adhesive Z-connections will influence the ability of [...] Read more.

This study used finite element analysis (FEA) to model the effects of adhesive Z-connections on the thickness swelling of laminated wood composites exposed to water. We hypothesized that the area density, diameter, and spatial distribution of adhesive Z-connections will influence the ability of Z-connections to restrain thickness swelling of the composites. We tested this hypothesis by modelling a wood composite in ANSYS FEA software v. 17.0 to explore the effect of moisture on the thickness swelling of the wood composite. The results were compared with those obtained experimentally. We then examined the effect of the area density, size (diam.), and spatial distribution of the adhesive Z-connections on the thickness swelling of wood composites. Our results showed a positive correlation between the number of adhesive Z-connections in the composites and restriction of thickness swelling following 72 h of simulated moisture diffusion. Similarly, increasing the size of adhesive Z-connections also restricted thickness swelling. In contrast, different spatial distributions of Z-connections had little effect on restraining thickness swelling. Our modelling approach opens up opportunities for more complex designs of adhesive Z-connections, and also to examine the effect of wood properties, such as permeability, density, and hygroscopic swelling ratios on the thickness swelling of laminated wood composites. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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21 pages, 18024 KiB

Open AccessArticle

The Intra-Ply Shear Behaviour of Non-Isothermal Thermoplastic Composite Laminates

by George E. Street and Michael S. Johnson

J. Compos. Sci. 2023, 7(10), 432; https://doi.org/10.3390/jcs7100432 - 13 Oct 2023

Cited by 1 | Viewed by 1736

Abstract

During the thermoforming of fibre-reinforced thermoplastic (FRTP) organosheets, the desire to minimise tool temperatures leads to non-isothermal temperature profiles through the laminate thickness. The aim of this study was to understand the influence of these non-isothermal conditions on FRTP intra-ply shearing. Novel non-isothermal [...] Read more.

During the thermoforming of fibre-reinforced thermoplastic (FRTP) organosheets, the desire to minimise tool temperatures leads to non-isothermal temperature profiles through the laminate thickness. The aim of this study was to understand the influence of these non-isothermal conditions on FRTP intra-ply shearing. Novel non-isothermal bias extension tests were conducted, revealing that an average between the isothermal shear curves of both laminate faces approximately represented the respective non-isothermal condition. However, these findings were irrespective of FRTP thickness, and only applied to laminates that wholly remained above the crystallisation onset temperature. Upon the onset of crystallisation in a single ply, the non-isothermal shear resistance skewed heavily towards that (within 5%) of the crystallised ply and inhomogeneous shear angles were observed. Non-isothermal thermoforming validated these findings with the presence of wrinkles on non-isothermal hemispheres in which a single ply had reached crystallisation. This reaffirms the importance of accurate thermal monitoring during FRTP processing. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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24 pages, 12336 KiB

Open AccessArticle

A Comparison of Three Simulation Techniques for Modeling the Fan Blade–Composite Abradable Rub Strip Interaction in Turbofan Engines

by Aleksandr Cherniaev

J. Compos. Sci. 2023, 7(9), 389; https://doi.org/10.3390/jcs7090389 - 14 Sep 2023

Cited by 1 | Viewed by 2034

Abstract

Turbofan engine models for foreign object impact simulations must include a representation of fan blade interactions with surrounding components of the engine, including rubbing against the abradable lining. In this study, three numerical techniques, namely, the finite element method (FEM), smoothed particles hydrodynamics [...] Read more.

Turbofan engine models for foreign object impact simulations must include a representation of fan blade interactions with surrounding components of the engine, including rubbing against the abradable lining. In this study, three numerical techniques, namely, the finite element method (FEM), smoothed particles hydrodynamics (SPH), and the adaptive (hybrid) FEM/SPH approach (ADT), were evaluated for their applicability to modeling of the blade–abradable rub strip (ARS) interaction. Models developed using these methods in the commercial code LS-DYNA were compared in terms of their computational cost, robustness, sensitivity to mesh density, and certain physical and non-physical parameters. As a result, the applicability of the models to represent the blade-ARS interaction was ranked as follows (1—most applicable, 3—least applicable): 1—SPH, 2—FEM, and 3—ADT. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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16 pages, 5431 KiB

Open AccessArticle

Mechanical Properties of Uncured Thermoset Tow Prepreg: Experiment and Finite Element Analysis

by Mina Derakhshani Dastjerdi, Massimo Carboni and Mehdi Hojjati

J. Compos. Sci. 2023, 7(8), 312; https://doi.org/10.3390/jcs7080312 - 29 Jul 2023

Cited by 1 | Viewed by 1694

Abstract

This paper presents an experimental analysis of the tensile behavior of unidirectional carbon/epoxy prepreg, focusing on the nonlinearity observed at the beginning of the stress–strain curve. Due to the material’s high viscosity, securely holding specimens during testing was challenging, prompting modifications in the [...] Read more.

This paper presents an experimental analysis of the tensile behavior of unidirectional carbon/epoxy prepreg, focusing on the nonlinearity observed at the beginning of the stress–strain curve. Due to the material’s high viscosity, securely holding specimens during testing was challenging, prompting modifications in the gripping method to ensure reliable data. By using a longer gauge length, the slippage impact on elastic modulus measurement was minimized, resulting in good repeatability among the test samples. Experimental findings highlighted the significant interaction between fiber waviness and the viscous matrix, leading to stiffness reduction. The linear stiffness of the samples closely matched that of the fibers and remained unaffected by temperature variations. However, at higher temperatures, the epoxy matrix’s decreased viscosity caused an upward shift in the stiffness plot within the non-linear region. To support the experimental findings, a micromechanical model of prepreg tow with fiber waviness was proposed. An RVE model of periodically distributed unidirectional waved cylindrical fibers embedded within the matrix was developed to predict effective material stiffness parameters. The simulation outcomes aligned well with the uniaxial tensile test of the prepreg tow, demonstrating the proposed RVE model’s capability to accurately predict elastic properties, considering factors like fiber arrangement, waviness, and temperature. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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15 pages, 4638 KiB

Open AccessArticle

An Efficient Method for Simulating the Temperature Distribution in Regions Containing YAG:Ce³⁺ Luminescence Composites of White LED

by Quang-Khoi Nguyen and Thi-Hanh-Thu Vu

J. Compos. Sci. 2023, 7(7), 301; https://doi.org/10.3390/jcs7070301 - 22 Jul 2023

Cited by 2 | Viewed by 1417

Abstract

A thermal model was built to estimate the temperature distribution in the hemispherical packaging volume of a white LED at a steady state. Inherent heat sources appeared in the white LED when its power was measured. A simplified 3D to 2D space process [...] Read more.

A thermal model was built to estimate the temperature distribution in the hemispherical packaging volume of a white LED at a steady state. Inherent heat sources appeared in the white LED when its power was measured. A simplified 3D to 2D space process that improves the model and solves the heat diffusion equation in a simpler and faster manner is presented. The finite element method was employed using MATLAB software (version R2017b) to identify the temperature distribution. The model was applied for different values of injection current, including 50 mA, 200 mA, 350 mA, and 500 mA. The influence of the injection current and thermal conductivity difference on the temperature distribution of the encapsulant, blue LED die, and substrate region was clearly observed. The results indicate that white light packaging technology should locate phosphor far from the LED die, that the thermal conductivity of the silicone–phosphor region should be improved, that heat should be dissipated for pc-WLEDs when using a high operating power, and that the injection current should be kept as moderate as possible. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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13 pages, 3999 KiB

Open AccessArticle

Statistical Analysis and Optimization of the Experimental Results on Performance of Green Aluminum-7075 Hybrid Composites

by Olanrewaju Seun Adesina, Abayomi Adewale Akinwande, Oluwatosin Abiodun Balogun, Adeolu Adesoji Adediran, Olufemi Oluseun Sanyaolu and Valentin Romanovski

J. Compos. Sci. 2023, 7(3), 115; https://doi.org/10.3390/jcs7030115 - 13 Mar 2023

Cited by 11 | Viewed by 1843

Abstract

The present study assessed the potential of engaging response surface analysis in the experimental design, modeling, and optimization of the strength performance of aluminum-7075 green composite. The design of the experiment was carried out via the Box–Behnken method and the independent variables are [...] Read more.

The present study assessed the potential of engaging response surface analysis in the experimental design, modeling, and optimization of the strength performance of aluminum-7075 green composite. The design of the experiment was carried out via the Box–Behnken method and the independent variables are rice husk ash (RHA) at 3–12 wt.%, glass powder (GP) at 2–10 wt.%, and stirring temperature (ST) at 600–800 °C. Responses examined are yield, ultimate tensile, flexural, and impact strengths, as well as microhardness and compressive strength. ANOVA analysis revealed that the input factors had consequential contributions to each response, eventually presenting regression models statistically fit to represent the experimental data, further affirmed by the diagnostic plots. The result of the optimization envisaged an optimal combination at 7.2% RHA, 6.2 GP, and 695 °C with a desirability of 0.910. A comparison between the predicted values for the responses and the values of the validation experiment revealed an error of <5% for each response. Consequently, the models are certified adequate for response predictions at 95% confidence, and the optimum combination is adequate for the design of the composite. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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12 pages, 2505 KiB

Open AccessArticle

A Mathematical Approach for Sound Insulation Characteristics and Cost Optimization of Double-Layer Composite Structures

by Liang Zhang, Huawei Zhang, Qiyu Chen and Danfeng Long

J. Compos. Sci. 2023, 7(3), 110; https://doi.org/10.3390/jcs7030110 - 9 Mar 2023

Cited by 2 | Viewed by 2364

Abstract

The compressor is the primary source of noise in a refrigeration system. Most compressors are wrapped with multi-layer sound insulation cotton for noise reduction and sound insulation. We explore the sound insulation law of different polyvinyl chloride thicknesses and non-woven fibers. Polyvinyl chloride [...] Read more.

The compressor is the primary source of noise in a refrigeration system. Most compressors are wrapped with multi-layer sound insulation cotton for noise reduction and sound insulation. We explore the sound insulation law of different polyvinyl chloride thicknesses and non-woven fibers. Polyvinyl chloride with varying thicknesses and non-woven fibers are then combined by bonding to study the sound insulation characteristics of a two-layer composite structure. A sound insulation prediction model is established using the multi-parameter nonlinear regression method. An optimal cost mathematical model is established based on experimental and mathematical methods that can quickly determine the optimal cost scheme for different designs with the same effect. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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23 pages, 4426 KiB

Open AccessArticle

Characterization of UV Light Curable Piezoelectric 0-0-3 Composites Filled with Lead-Free Ceramics and Conductive Nanoparticles

by Rytis Mitkus, Lena Piechowiak and Michael Sinapius

J. Compos. Sci. 2023, 7(2), 89; https://doi.org/10.3390/jcs7020089 - 20 Feb 2023

Cited by 3 | Viewed by 2356

Abstract

Lead-free piezoelectric materials are essential for our healthy future but offer lower performance than lead-based materials. Different material combinations are explored to improve the performance of lead-free materials. By filling the UV light curable photopolymer resin with 30 vol.% lead-free piezoelectric ceramics and [...] Read more.

Lead-free piezoelectric materials are essential for our healthy future but offer lower performance than lead-based materials. Different material combinations are explored to improve the performance of lead-free materials. By filling the UV light curable photopolymer resin with 30 vol.% lead-free piezoelectric ceramics and with up to 0.4 wt.% conductive nanofillers, thin and flexible piezoelectric 0-0-3 composites are formed. Two particle sizes of Potassium Sodium Niobate (KNN) and Barium Titanate (BTO) ceramics were used with four conductive nanofillers: Graphene Nanoplatelets (GNPs), Multi-Walled Carbon Nanotubes (MWCNTs), and two types of Graphene Oxide (GO). Resulting high viscosity suspensions are tape-cast in a mold as thin layers and subsequently exposing them to UV light, piezoelectric composite sensors are formed in 80 s. Even low nanofiller concentrations increase relative permittivities, however, they strongly reduce curing depth and increase undesirable dielectric losses. Non-homogeneous dispersion of nanofillers is observed. In total, 36 different compositions were mixed and characterized. Only six selected material compositions were investigated further by measuring mechanical, dielectric, and piezoelectric properties. Results show KNN composite performance as piezoelectric sensors is almost six times higher than BTO composite performance. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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13 pages, 19409 KiB

Open AccessArticle

Micro-Scale Model of rCF/PA6 Spun Yarn Composite

by Tobias Georg Lang, Mir Mohammad Badrul Hasan, Anwar Abdkader, Chokri Cherif and Thomas Gereke

J. Compos. Sci. 2023, 7(2), 66; https://doi.org/10.3390/jcs7020066 - 6 Feb 2023

Cited by 2 | Viewed by 1701

Abstract

Recycling carbon fibers (rCF) for reuse is one approach to improve the sustainability of CFRP. However, until now, recycled carbon fiber plastics (rCFRP) had limited composite properties due to the microgeometry of the fibers, which made it difficult to use in load-bearing components. [...] Read more.

Recycling carbon fibers (rCF) for reuse is one approach to improve the sustainability of CFRP. However, until now, recycled carbon fiber plastics (rCFRP) had limited composite properties due to the microgeometry of the fibers, which made it difficult to use in load-bearing components. The production of hybrid yarns from rCF and PA6 fibers allows the fibers to be aligned. The geometric properties of the yarn and the individual fibers influence the mechanical properties of the composite. An approach for the modeling and simulation of hybrid yarns consisting of recycled carbon fibers and thermoplastic fibers is presented. The yarn unit cell geometry is modeled in the form of a stochastic fiber network. The fiber trajectory is modeled in form of helical curves using the idealized yarn model of Hearle et al. The variability in the fiber geometry (e.g., length) is included in form of statistical distributions. An additional compaction step ensures a realistic composite geometry. The created model is validated geometrically and by comparison with tensile tests of manufactured composites. With the validated model, multiple parameter studies investigating the influence of fiber and yarn geometry are carried out. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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20 pages, 3351 KiB

Open AccessArticle

Comparative Analysis of ANN-MLP, ANFIS-ACO_R and MLR Modeling Approaches for Estimation of Bending Strength of Glulam

by Morteza Nazerian, Masood Akbarzadeh and Antonios N. Papadopoulos

J. Compos. Sci. 2023, 7(2), 57; https://doi.org/10.3390/jcs7020057 - 4 Feb 2023

Cited by 5 | Viewed by 1617

Abstract

Multiple linear regression (MLR), adaptive network-based fuzzy inference system–ant colony optimization algorithm hybrid (ANFIS-ACO_R) and artificial neural network–multilayer perceptron (ANN-MLP) were tested to model the bending strength of Glulam (glue-laminated timber) manufactured with a plane tree (Platanus orientalis L.) wood [...] Read more.

Multiple linear regression (MLR), adaptive network-based fuzzy inference system–ant colony optimization algorithm hybrid (ANFIS-ACO_R) and artificial neural network–multilayer perceptron (ANN-MLP) were tested to model the bending strength of Glulam (glue-laminated timber) manufactured with a plane tree (Platanus orientalis L.) wood layer adhered with different weight ratios (WR) of modified starch/urea formaldehyde (UF) adhesive containing different levels of nano-ZnO (NC) used at different levels of the press temperature (Tem) and time (Tim). According to X-ray diffraction (XRD) and stress–strain curves, some changes in the behavior of the product were seen. After selecting the best model through determining statistics such as the determination coefficient (R2) and root mean square error (RMSE), mean absolute error (MAE) and sum of squares error (SSE), the production process was optimized to obtain the highest modulus of rupture (MOR) using the Genetic Algorithm (GA) combined with MLP. It was determined that the MLP had the best accuracy in estimating the response. According to the MLP-GA hybrid, the optimum input values for obtaining the best response include: WR—49.1%, NC—3.385%, Tem—199.4 °C and Tim—19.974 min. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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12 pages, 2923 KiB

Open AccessArticle

On the Influence of Fatigue Damage in Short-Fibre Reinforced Thermoplastic PBT GF30 on Its Residual Strength under High Strain Rates: An Approach towards Simulative Prediction

by Christian Witzgall, Patrick Steck and Sandro Wartzack

J. Compos. Sci. 2023, 7(1), 23; https://doi.org/10.3390/jcs7010023 - 10 Jan 2023

Cited by 3 | Viewed by 2078

Abstract

Only by using accurate material data can precise simulation results be achieved. This principle also and especially applies in the field of crash simulation. However, in the simulation of short-fibre reinforced thermoplastics, material parameters are usually used that originate from the material testing [...] Read more.

Only by using accurate material data can precise simulation results be achieved. This principle also and especially applies in the field of crash simulation. However, in the simulation of short-fibre reinforced thermoplastics, material parameters are usually used that originate from the material testing of as-new samples. In order to get closer to the condition on the roads, where not only new vehicles are driving, the influence of service loads on the crashworthiness has to be investigated. This paper reports on studies of PBT GF30, a polybutylene terephthalate reinforced with 30% glass fibres, in which fatigue damage was induced in the material by cyclic loading. The residual strength was then determined in a high-speed experiment and compared with the strength of virgin samples. In order to enable the usability of the findings in the simulation, a modified failure criterion was implemented that takes the previous fatigue damage into account. The prediction quality of the simulation model was compared with the experimental findings and it can be concluded that there is good agreement. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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13 pages, 1664 KiB

Open AccessArticle

Development of Prediction Models for the Torsion Capacity of Reinforced Concrete Beams Using M5P and Nonlinear Regression Models

by Sadiq N. Henedy, Ali H. Naser, Hamza Imran, Luís F. A. Bernardo, Mafalda M. Teixeira and Zainab Al-Khafaji

J. Compos. Sci. 2022, 6(12), 366; https://doi.org/10.3390/jcs6120366 - 2 Dec 2022

Cited by 7 | Viewed by 1677

Abstract

Torsional strength is related with one of the most critical failure types for the design and assessment of reinforced concrete (RC) members due to the complexity of the associated stress state and low ductility. Previous studies have shown that reliable methods to predict [...] Read more.

Torsional strength is related with one of the most critical failure types for the design and assessment of reinforced concrete (RC) members due to the complexity of the associated stress state and low ductility. Previous studies have shown that reliable methods to predict the torsional strength of RC beams are still needed, namely for over-reinforced and high-strength RC beams. This research aims to offer a novel set of models to predict the torsional strength of RC beams with a wide range of design attributes and geometries by using advanced M5P tree and nonlinear regression models. For this, a broad database with 202 experimental tests is used to generate highly reliable and resilient models. To build the models, three independent variables related with the properties of the RC beams are considered: concrete cross-section area (area enclosed within the outer perimeter of the cross-section), concrete compressive strength, and torsional reinforcement factor (which accounts for the type—longitudinal or transverse—amount, and yielding strength of the torsional reinforcement). In contrast to multiple nonlinear regression approaches, the findings show that the M5P tree approach has the best estimation in terms of both accuracy and safety. Furthermore, M5P model predictions are far more accurate and safer than the most prevalent design equations. Finally, sensitivity and parametric studies are used to confirm the robustness of the presented models. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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16 pages, 6994 KiB

Open AccessArticle

Micromechanical Approach to Predict Mechanical Properties of Particulate-Dispersed Composites with Dissimilar Interfacial Phases

by Tomoyuki Fujii, Keiichiro Tohgo, Takahiro Omi and Yoshinobu Shimamura

J. Compos. Sci. 2022, 6(12), 356; https://doi.org/10.3390/jcs6120356 - 22 Nov 2022

Cited by 2 | Viewed by 1447

Abstract

The mechanical properties of composites are affected by their constituents. For the development of high-performance composites, it is expected that a technique will be developed which can predict the mechanical properties of composites based on the mechanical properties of their constituents. This study [...] Read more.

The mechanical properties of composites are affected by their constituents. For the development of high-performance composites, it is expected that a technique will be developed which can predict the mechanical properties of composites based on the mechanical properties of their constituents. This study developed a technique based on a micromechanical approach to predict the mechanical properties of composites with interfacial phases between reinforcements and matrix. A double-inclusion model (Hori and Nemat-Nasser, 1993) is effective for the solution of such problems, of which the validity remains unclear. Problems with a particle surrounded by an interfacial phase embedded in an infinite body were calculated via the model and finite element analysis to verify the model. It was found that the macroscopic average stress of the double inclusion could be accurately solved by the model, although the microscopic stress of each phase could not be calculated with high accuracy. Therefore, a micromechanical approach based on the model was formulated and applied to particulate-dispersed composites consisting of zirconia and titanium, and fabricated by spark plasma sintering, in which Ti oxides were created along the interface between zirconia and titanium. As a result, the elastic-plastic stress–strain curves of the composites could be predicted. The approach can investigate the mechanical properties of composites with various shapes of reinforcement surrounded by dissimilar materials in a matrix. It can be concluded that the approach is promising for the development of composites with an excellent mechanical performance. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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13 pages, 3352 KiB

Open AccessArticle

Investigation of Mechanical Properties of Coffee Husk-HDPE-ABS Polymer Composite Using Injection-Molding Method

by Berhanu Tolessa Amena, Holm Altenbach, Getechew Shunki Tibba and Nazia Hossain

J. Compos. Sci. 2022, 6(12), 354; https://doi.org/10.3390/jcs6120354 - 22 Nov 2022

Cited by 9 | Viewed by 2661

Abstract

Waste biomass-based natural fibers are being extensively researched nowadays as a composite material with various waste-based high-density polyethylene (HDPE) to utilize the waste biomass and recycle the plastic waste in an effective approach. In this study, chemically modified spent coffee husk (CH) has [...] Read more.

Waste biomass-based natural fibers are being extensively researched nowadays as a composite material with various waste-based high-density polyethylene (HDPE) to utilize the waste biomass and recycle the plastic waste in an effective approach. In this study, chemically modified spent coffee husk (CH) has been applied with different ratios of HDPE to produce composite material and characterized comprehensively to determine the mechanical stability of the products. The injection molding method was used for composite development containing HDPE with untreated and 10 wt% NaOH-treated CH weight ratios of 0%, 15%, 20%, and 25% together with 10 wt% coupling agent and filler materials of acrylonitrile butadiene styrene (ABS) and kaolin clay, respectively. Physicochemical characteristics of untreated CH, 10 wt% NaOH treated CH, pristine HDPE and HDPE-CH composites have been analyzed comprehensively in this study. Adding 25 wt% fiber with 65 wt% HDPE and 10 wt% of ABS (7 wt%)-kaolin clay (3 wt%) increased the tensile and bending properties significantly. This composite presented the maximum tensile, flexural, and impact strengths, which were 36 MPa, 7.5 MPa, and 2.8 KJ/m², respectively. The tensile strength and bending strength of NaOH-treated coffee husk fibers (CHF) were enhanced by 32% and 29%, respectively. The microstructural characteristics of HDPE with treated and untreated CHF composites analyzed by scanning electron microscopy (SEM) demonstrated the fibers’ and matrix’s excellent adhesion and compatibility. Thus, HDPE polymer-treated CH composite presented excellent stability, which can be expected as a new addition for construction, food packaging, and other industrial applications. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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22 pages, 4663 KiB

Open AccessArticle

Influence of Spatially Distributed Out-of-Plane CFRP Fiber Waviness on the Estimation of Knock-Down Factors Based on Stochastic Numerical Analysis

by Andreas Schuster, Richard Degenhardt, Christian Willberg and Tobias Wille

J. Compos. Sci. 2022, 6(12), 353; https://doi.org/10.3390/jcs6120353 - 22 Nov 2022

Cited by 1 | Viewed by 1451

Abstract

The presence of waviness defects in CFRP materials due to fiber undulation affects the structural performance of composite structures. Hence, without a reliable assessment of the resulting material properties, the full weight-saving potential cannot be exploited. Within the paper, a probabilistic numerical approach [...] Read more.

The presence of waviness defects in CFRP materials due to fiber undulation affects the structural performance of composite structures. Hence, without a reliable assessment of the resulting material properties, the full weight-saving potential cannot be exploited. Within the paper, a probabilistic numerical approach for improved estimation of material properties based on spatially distributed fiber waviness is presented. It makes use of a homogenization approach to derive viable knock-down factors for the different plies on the laminate level for reference material and is demonstrated for a representative tension loadcase. For the stochastic analysis, a random field is selected which describes the complex inner geometry of the plies in the laminate model and is numerically discretized by the Karhunen–Loeve expansion methods to fit into an FE model for the strength analysis. Conducted analysis studies reveal a substantial influence of randomly distributed waviness defects on the derived knock-down factors. Based on a topological analysis of the waviness fields, the reduction of the material properties was found to be weakly negatively correlated related to simple geometrical properties such as maximum amplitudes of the waviness field, which justifies the need for further subsequent sensitivity studies. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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16 pages, 5475 KiB

Open AccessArticle

Utilizing of Magnetized Water in Enhancing of Volcanic Concrete Characteristics

by Mostafa M. Keshta, Mohamed M. Yousry Elshikh, Mohamed Abd Elrahman and Osama Youssf

J. Compos. Sci. 2022, 6(10), 320; https://doi.org/10.3390/jcs6100320 - 19 Oct 2022

Cited by 16 | Viewed by 2594

Abstract

Volcanic concrete is an eco-friendly concrete type in that it contains coarse and fine aggregates that all extracted from the igneous volcanic rock. However, utilizing of volcanic ash (VA) as partial/full replacement of concrete cement significantly affects the concrete workability, especially at high [...] Read more.

Volcanic concrete is an eco-friendly concrete type in that it contains coarse and fine aggregates that all extracted from the igneous volcanic rock. However, utilizing of volcanic ash (VA) as partial/full replacement of concrete cement significantly affects the concrete workability, especially at high cement replacement ratios. This has also some adverse effects on concrete strength. Utilizing magnetized water (MW) in concrete as a partial/full replacement of ordinary tap water (TW) has a notable effect on enhancing the fresh and hardened concrete properties. This research aims to study the effect of using MW prepared in a magnetic field of 1.4 Tesla on the workability and hardened properties (compressive, tensile, and flexural strengths) of volcanic concrete. In this study, VA partially replaced volcanic concrete cement with ratios of 5%, 10%, 15%, and 20%. Ten volcanic concrete mixes were prepared in two groups. The first one was prepared with VA (0–20%) and mixed with TW. The other group was prepared with the same VA contents like group one, but mixed with MW. Microstructure imaging for volcanic concrete was also conducted in this study. Results of water tests showed 17% and 15% increase in total dissolved solids (TDS) and pH, respectively, of MW compared with those of TW. In addition, the water magnetization decreased the water surface tension by 7% compared with that of TW. Results of hardened concrete tests showed that the best ratio of VA in volcanic concrete was 5% with and without using magnetized water. The volcanic concrete slump decreased when using TW; however, using MW enhanced the volcanic concrete slump by up to 8%. The compressive strength was improved by 35%, 23%, and 20% at 7 days, 28 days, and 120 days, respectively, with no VA and with the presence of MW. The compressive strength was improved by 11%, 12%, and 11% after 7 days, 28 days, and 120 days, respectively, with using 5% VA and with the presence of MW. Both splitting tensile strength and flexural strength of volcanic concrete with and without VA or MW behaved similar to that of the corresponding compressive strength. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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13 pages, 3517 KiB

Open AccessArticle

Mixed-Mode I/II Testing of Composite Materials—A Refined Data Reduction Scheme for the Wedge-Loaded Asymmetric Double Cantilever Beam Test

by Michael May, Philipp Hahn, Borhan Uddin Manam and Mathieu Imbert

J. Compos. Sci. 2022, 6(10), 319; https://doi.org/10.3390/jcs6100319 - 18 Oct 2022

Cited by 6 | Viewed by 2388

Abstract

The wedge-loaded asymmetric double cantilever beam (WADCB) test is an experimental method to determine the mixed-mode I/II fracture toughness of composite materials by inserting a wedge into the specimen along a potential delamination path. Whilst the current closed-form solution for the ADCB test [...] Read more.

The wedge-loaded asymmetric double cantilever beam (WADCB) test is an experimental method to determine the mixed-mode I/II fracture toughness of composite materials by inserting a wedge into the specimen along a potential delamination path. Whilst the current closed-form solution for the ADCB test assumes identical forces acting in both specimen arms, this manuscript proposes a refined closed-form solution allowing for different forces acting on both specimen arms, which is thought to be more general and more rigorous. WADCB tests were carried out on composites made from Torayca T700SC/2592 unidirectional prepreg. Both the current and the refined closed-form solution were used to analyze the data, and some differences were found in the predictions, indicating that the forces in the two specimen arms are indeed not identical. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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10 pages, 1935 KiB

Open AccessArticle

Threshold Identification and Damage Characterization of Woven GF/CF Composites under Low-Velocity Impact

by Marzio Grasso and Yigeng Xu

J. Compos. Sci. 2022, 6(10), 305; https://doi.org/10.3390/jcs6100305 - 11 Oct 2022

Cited by 3 | Viewed by 1659

Abstract

The Delamination Threshold Load (DTL) is a key parameter representing damage resistance of a laminate and is normally identified by locating a sudden drop in the impact force-time history for the laminate made of unidirectional layers. For the woven composite, however, their failure [...] Read more.

The Delamination Threshold Load (DTL) is a key parameter representing damage resistance of a laminate and is normally identified by locating a sudden drop in the impact force-time history for the laminate made of unidirectional layers. For the woven composite, however, their failure mechanisms appear different and the current literature is not providing any clear procedure regarding the identification of the delamination initiation, as well as the evolution of the failure mechanisms associated with it. In this paper, experimental data have been collected using woven glass and carbon fiber composites. The results are analyzed in terms of force-time and force-displacement curves. While delamination and other damages were clearly observed using ultrasonic scans, the analysis of the results does not reveal any trend changes of the curves that can be associated with the incipient nucleation of delamination. A preliminary discussion regarding the nature of the mechanisms through which the delamination propagates in woven composite and a justification for the absence of a sudden change of the stiffness have been presented. It raises a question on the existence of DTL for woven composites under low velocity impact. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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16 pages, 6694 KiB

Open AccessArticle

Mitigation of Heat Propagation in a Battery Pack by Interstitial Graphite Nanoplatelet Layer: Coupled Electrochemical-Heat Transfer Model

by Barbara Palmieri, Fabrizia Cilento, Ciro Siviello, Francesco Bertocchi, Michele Giordano and Alfonso Martone

J. Compos. Sci. 2022, 6(10), 296; https://doi.org/10.3390/jcs6100296 - 9 Oct 2022

Cited by 9 | Viewed by 2342

Abstract

The use of high thermal conductive materials for heat transfer is gaining attention as a suitable treatment for improving battery performance. Thermal runaway is a relevant issue for maintaining safety and for proficient employment of accumulators; therefore, new solutions for thermal management are [...] Read more.

The use of high thermal conductive materials for heat transfer is gaining attention as a suitable treatment for improving battery performance. Thermal runaway is a relevant issue for maintaining safety and for proficient employment of accumulators; therefore, new solutions for thermal management are mandatory. For this purpose, a hierarchical nanomaterial made of graphite nanoplatelet has been considered as an interface material. High-content graphite nanoplatelet films have very high thermal conductivity and might improve heat dissipation. This study investigates the effect of a thermally conductive material as a method for safety enhancement for a battery module. A numerical model based on the finite element method has been developed to predict the heat generation during a battery pack’s charge and discharge cycle, using the Multiphysics software Comsol. The lumped battery interface generates appropriate heat sources coupled to the Heat Transfer Interface in 3D geometry. Simulation results show that the protection of neighbouring cells from the interleaved layer is fundamental for avoiding heat propagation and an uncontrollable heating rise of the entire battery pack. The use of graphite nanocomposite sheets could effectively help to uniform the temperature and delay the TR propagation. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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10 pages, 3231 KiB

Open AccessArticle

A Study on the Structural Features of Amorphous Nanoparticles of Ni by Molecular Dynamics Simulation

by Tuan Tran Quoc, Dung Nguyen Trong, Van Cao Long, Umut Saraç and Ştefan Ţălu

J. Compos. Sci. 2022, 6(9), 278; https://doi.org/10.3390/jcs6090278 - 19 Sep 2022

Cited by 3 | Viewed by 1753

Abstract

This study deals with the impact of the heating rate (HR), temperature (T), and the number of atoms (N) on the structural features of amorphous nanoparticles (ANPs) of Ni by molecular dynamics simulation (MDS) with the Pak–Doyama pair interaction potential field (PD). The [...] Read more.

This study deals with the impact of the heating rate (HR), temperature (T), and the number of atoms (N) on the structural features of amorphous nanoparticles (ANPs) of Ni by molecular dynamics simulation (MDS) with the Pak–Doyama pair interaction potential field (PD). The obtained results showed that the structural features of ANPs of Ni are significantly affected by the studied factors. The correlation between the size (D) and the N was determined to be D~N^−1/3. The energy (E) was proportional to N⁻¹, and the Ni-Ni link length was 2.55 Å. The glass transition temperature (T_g) derived from the E-T graph was estimated to be 630 K. An increase in the HR induced a change in the shape of the ANPs of Ni. Furthermore, raising the HR caused an enhancement in the D and a decrement in the density of atoms. The obtained results are expected to contribute to future empirical studies. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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13 pages, 3726 KiB

Open AccessArticle

Finite Element Simulation of FRP-Strengthened Thin RC Slabs

by Maha Assad, Rami Hawileh and Jamal Abdalla

J. Compos. Sci. 2022, 6(9), 263; https://doi.org/10.3390/jcs6090263 - 8 Sep 2022

Cited by 11 | Viewed by 2047

Abstract

This study aims to investigate the flexural behavior of high-strength thin slabs externally strengthened with fiber-reinforced polymer (FRP) laminates through a numerical simulation. A three-dimensional (3D) finite element (FE) model is created to simulate the response of strengthened reinforced concrete (RC) slabs under [...] Read more.

This study aims to investigate the flexural behavior of high-strength thin slabs externally strengthened with fiber-reinforced polymer (FRP) laminates through a numerical simulation. A three-dimensional (3D) finite element (FE) model is created to simulate the response of strengthened reinforced concrete (RC) slabs under a four-point bending test. The numerical model results in terms of load-deflection behavior, and ultimate loads are verified using previously published experimental data in the literature. The numerical results show a good agreement with the experimental results. The FE model is then employed in a parametric study to inspect the effect of concrete compressive strength on the performance of RC thin slabs strengthened with different FRP types, namely carbon fiber-reinforced polymers (CFRP), polyethylene terephthalate fiber-reinforced polymers (PET-FRP), basalt fiber-reinforced polymers (BFRP) and glass fiber-reinforced polymers (GFRP). The results showed that the highest strength enhancement was obtained by the slab that was strengthened by CFRP sheets. Slabs that were strengthened with other types of FRP sheets showed an almost similar flexural capacity. The effect of concrete compressive strength on the flexural behavior of the strengthened slabs was moderate, with the highest effect being a 15% increase in the ultimate load between two consecutive values of compressive strength, occurring in the CFRP-strengthened slabs. It can thus be concluded that the developed FE model could be used as a platform to predict the behavior of reinforced concrete slabs when strengthened with different types of FRP composites. It can also be concluded that the modulus of elasticity of the composite plays a major role in determining the flexural capacity of the strengthened slabs. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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15 pages, 6263 KiB

Open AccessArticle

Experimental and Finite Element Study of a Novel Two-Way Corrugated Steel Deck System for Composite Slabs

by Keerthana John, Mahmud Ashraf, Matthias Weiss and Riyadh Al-Ameri

J. Compos. Sci. 2022, 6(9), 261; https://doi.org/10.3390/jcs6090261 - 8 Sep 2022

Cited by 3 | Viewed by 2170

Abstract

This paper investigates the structural performance of a new two-way profiled steel decking system for steel-concrete composite slabs. Several studies have investigated steel decking for steel-concrete composite slabs and focused on utilising the conventional deck as a one-way floor system. The newly developed [...] Read more.

This paper investigates the structural performance of a new two-way profiled steel decking system for steel-concrete composite slabs. Several studies have investigated steel decking for steel-concrete composite slabs and focused on utilising the conventional deck as a one-way floor system. The newly developed deck consists of top-hat sections formed by bending corrugated sheets at 90°, which are attached to a corrugated base sheet. The deck is designed for improved composite and two-way action contributed by its unique geometry due to corrugations in the transverse and longitudinal directions. This paper experimentally tested a novel steel decking geometry under construction stage loading. It was in the absence of concrete to establish the deck’s suitability for construction and contribution towards loading capacity and performance for future use as a two-way composite slab. Ultimate load, two-way action, and failure modes were identified. A finite element model was also developed, and parameters assessed that could influence the performance when the deck is potentially used in the composite stage. It was concluded that, while increasing the thickness of the corrugated base sheet significantly affects the load-carrying capacity, the thickness of the top hats has no significant impact. Improved load transfer with two-way behaviour is observed when the bottom flanges of the top hats are continuously connected to the bottom flanges of the adjacent top hats to form a deck. This contrasts with the concept deck, where individual top hats are attached to a corrugated base sheet. In this case, decks with a corrugated base sheet perform 54% better in ultimate load capacity than decks without a corrugated base sheet. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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22 pages, 4853 KiB

Open AccessArticle

Development and Characterization of PHB-PLA/Corncob Composite for Fused Filament Fabrication

by Okezie Ohaeri and Duncan Cree

J. Compos. Sci. 2022, 6(9), 249; https://doi.org/10.3390/jcs6090249 - 26 Aug 2022

Cited by 8 | Viewed by 2447

Abstract

The development of environmentally friendly polymeric composites holds great potential for agricultural leftovers. This study explores the effects of lignocellulosic corncob powder as a filler in a polyhydroxybutyrate (PHB)/polylactic acid (PLA) biopolymer matrix. The PHB-PLA matrix consists of a 55% to 45% blend, [...] Read more.

The development of environmentally friendly polymeric composites holds great potential for agricultural leftovers. This study explores the effects of lignocellulosic corncob powder as a filler in a polyhydroxybutyrate (PHB)/polylactic acid (PLA) biopolymer matrix. The PHB-PLA matrix consists of a 55% to 45% blend, respectively, while the filler loadings range from 0 wt.% to 8 wt.%. The components are combined and directly extruded into fused filaments for three-dimensional (3D) printing. The tensile strength of both the filament and dog-bone samples, flexural strength, and Charpy impact toughness of the composites, all decreased as filler loading increased. The tensile and flexural modulus of all samples examined improved noticeably with increasing filler loading. The filler particles had dense, mildly elongated sheet-like shapes, whereas the fractured surfaces of the composite samples had flat features for the pure polymer blend, but became rougher and jagged as filler loading increased. The fractured surface of Charpy impact test samples had smoother morphology when tested at cryogenic temperatures, compared to room temperature testing. All attributes showed a fourth-degree polynomial relationship to filler loading and all improved as filler loading increased, with the best results obtained at 6 wt.% loading. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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17 pages, 56661 KiB

Open AccessArticle

Prediction of Damage in Non-Crimp Fabric Composites Subjected to Transverse Crushing: A Comparison of Two Constitutive Models

by Milad Kazemian and Aleksandr Cherniaev

J. Compos. Sci. 2022, 6(8), 224; https://doi.org/10.3390/jcs6080224 - 4 Aug 2022

Cited by 1 | Viewed by 2462

Abstract

Non-crimp fabrics (NCFs) are increasingly used in industry for manufacturing of composite structures due to a combination of high mechanical properties and excellent manufacturability. As with other composites, in-service damage can be a cause for severe reduction in load-carrying capacity of NCF-reinforced plastics. [...] Read more.

Non-crimp fabrics (NCFs) are increasingly used in industry for manufacturing of composite structures due to a combination of high mechanical properties and excellent manufacturability. As with other composites, in-service damage can be a cause for severe reduction in load-carrying capacity of NCF-reinforced plastics. In this experimental and numerical study, two constitutive material models previously used only for damage prediction in unidirectional (UD) tape and woven fabric-reinforced materials (LS-DYNA’s *MAT_ENHANCED_COMPOSITE_DAMAGE—MAT54 and *MAT_LAMINATED_COMPOSITE_FABRIC—MAT58) were evaluated for simulating transverse crushing of composite parts processed from a non-crimp carbon fabric. For this purpose, UD NCF components of tubular shape were subjected to transverse crushing through a controlled indentation of a metallic cylinder, and results of the experiment were compared with numerical modeling. Considered verification metrics included the observed and the predicted patterns of interlaminar damage, the extent of delamination, as well as the ability of the models to replicate force-displacement response exhibited by the tested specimens. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Review

Jump to: Editorial, Research

28 pages, 9470 KiB

Open AccessReview

Advancement in the Modeling and Design of Composite Pressure Vessels for Hydrogen Storage: A Comprehensive Review

by Lyazid Bouhala, Argyrios Karatrantos, Heiner Reinhardt, Norbert Schramm, Beril Akin, Alexander Rauscher, Anton Mauersberger, Senagül Tunca Taşkıran, Muhammed Erdal Ulaşlı, Engin Aktaş and Metin Tanoglu

J. Compos. Sci. 2024, 8(9), 339; https://doi.org/10.3390/jcs8090339 - 29 Aug 2024

Viewed by 1649

Abstract

The industrial and technological sectors are pushing the boundaries to develop a new class of high-pressure vessels for hydrogen storage that aim to improve durability and and endure harsh operating conditions. This review serves as a strategic foundation for the integration of hydrogen [...] Read more.

The industrial and technological sectors are pushing the boundaries to develop a new class of high-pressure vessels for hydrogen storage that aim to improve durability and and endure harsh operating conditions. This review serves as a strategic foundation for the integration of hydrogen tanks into transport applications while also proposing innovative approaches to designing high-performance composite tanks. The goal is to offer optimized, safe, and cost-effective solutions for the next generation of high-pressure vessels, contributing significantly to energy security through technological advancements. Additionally, the review deepens our understanding of the relationship between microscopic failure mechanisms and the initial failure of reinforced composites. The investigation will focus on the behavior and damaging processes of composite overwrapped pressure vessels (COPVs). Moreover, the review summarizes relevant simulation models in conjunction with experimental work to predict the burst pressure and to continuously monitor the degree of structural weakening and fatigue lifetime of COPVs. Simultaneously, understanding the adverse effects of in-service applications is vital for maintaining structural health during the operational life cycle. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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32 pages, 6776 KiB

Open AccessReview

A Review on the Modelling of Aligned Discontinuous Fibre Composites

by Chantal Lewis, Burak Ogun Yavuz, Marco L. Longana, Jonathan P.-H. Belnoue, Karthik Ram Ramakrishnan, Carwyn Ward and Ian Hamerton

J. Compos. Sci. 2024, 8(8), 318; https://doi.org/10.3390/jcs8080318 - 12 Aug 2024

Viewed by 1258

Abstract

Aligned discontinuous fibre-reinforced composites are becoming more popular because they have the potential to offer stiffness and strength comparable to their continuous counterparts along with better manufacturability. However, the modelling of highly aligned discontinuous fibre composites is still in its infancy. This paper [...] Read more.

Aligned discontinuous fibre-reinforced composites are becoming more popular because they have the potential to offer stiffness and strength comparable to their continuous counterparts along with better manufacturability. However, the modelling of highly aligned discontinuous fibre composites is still in its infancy. This paper aims to provide a comprehensive review of the available literature to understand how modelling techniques have developed and consider whether all aspects which could affect the performance of aligned discontinuous fibre composites have been addressed. Here, for the first time, a broad view of the advantages, perspectives, and limitations of current approaches to modelling the performance and behaviour of aligned discontinuous fibre composites during alignment, forming, and mechanical loading is provided in one place as a route to design optimisation. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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26 pages, 2124 KiB

Open AccessReview

Material Characterization Required for Designing Satellites from Fiber-Reinforced Polymers

by Esha and Joachim Hausmann

J. Compos. Sci. 2023, 7(12), 515; https://doi.org/10.3390/jcs7120515 - 11 Dec 2023

Cited by 1 | Viewed by 2491

Abstract

This review paper discusses the effect of polymers, especially thermoplastics, in environments with low earth orbits. Space weather in terms of low earth orbits has been characterized into seven main elements, namely microgravity, residual atmosphere, high vacuum, atomic oxygen, ultraviolet and ionization radiation, [...] Read more.

This review paper discusses the effect of polymers, especially thermoplastics, in environments with low earth orbits. Space weather in terms of low earth orbits has been characterized into seven main elements, namely microgravity, residual atmosphere, high vacuum, atomic oxygen, ultraviolet and ionization radiation, solar radiation, and space debris. Each element is discussed extensively. Its effect on polymers and composite materials has also been studied. Quantification of these effects can be evaluated by understanding the mechanisms of material degradation caused by each environmental factor along with its synergetic effect. Hence, the design elements to mitigate the material degradation can be identified. Finally, a cause-and-effect diagram (Ishikawa diagram) is designed to characterize the important design elements required to investigate while choosing a material for a satellite’s structure. This will help the designers to develop experimental methodologies to test the composite material for its suitability against the space environment. Some available testing facilities will be discussed. Some potential polymers will also be suggested for further evaluation. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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21 pages, 1640 KiB

Open AccessReview

Review on Characterization of Biochar Derived from Biomass Pyrolysis via Reactive Molecular Dynamics Simulations

by Zhong Hu and Lin Wei

J. Compos. Sci. 2023, 7(9), 354; https://doi.org/10.3390/jcs7090354 - 25 Aug 2023

Cited by 6 | Viewed by 3699

Abstract

Biochar is a carbon-rich solid produced during the thermochemical processes of various biomass feedstocks. As a low-cost and environmentally friendly material, biochar has multiple significant advantages and potentials, and it can replace more expensive synthetic carbon materials for many applications in nanocomposites, energy [...] Read more.

Biochar is a carbon-rich solid produced during the thermochemical processes of various biomass feedstocks. As a low-cost and environmentally friendly material, biochar has multiple significant advantages and potentials, and it can replace more expensive synthetic carbon materials for many applications in nanocomposites, energy storage, sensors, and biosensors. Due to biomass feedstock species, reactor types, operating conditions, and the interaction between different factors, the compositions, structure and function, and physicochemical properties of the biochar may vary greatly, traditional trial-and-error experimental approaches are time consuming, expensive, and sometimes impossible. Computer simulations, such as molecular dynamics (MD) simulations, are an alternative and powerful method for characterizing materials. Biomass pyrolysis is one of the most common processes to produce biochar. Since pyrolysis of decomposing biomass into biochar is based on the bond-order chemical reactions (the breakage and formation of bonds during carbonization reactions), an advanced reactive force field (ReaxFF)-based MD method is especially effective in simulating and/or analyzing the biomass pyrolysis process. This paper reviewed the fundamentals of the ReaxFF method and previous research on the characterization of biochar physicochemical properties and the biomass pyrolysis process via MD simulations based on ReaxFF. ReaxFF implicitly describes chemical bonds without requiring quantum mechanics calculations to disclose the complex reaction mechanisms at the nano/micro scale, thereby gaining insight into the carbonization reactions during the biomass pyrolysis process. The biomass pyrolysis and its carbonization reactions, including the reactivity of the major components of biomass, such as cellulose, lignin, and hemicellulose, were discussed. Potential applications of ReaxFF MD were also briefly discussed. MD simulations based on ReaxFF can be an effective method to understand the mechanisms of chemical reactions and to predict and/or improve the structure, functionality, and physicochemical properties of the products. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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