Journal of Composites Science

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16 pages, 6230 KiB

Open AccessArticle

Analysis and Modeling of Wrinkling in Composite Forming

by Philippe Boisse, Jin Huang and Eduardo Guzman-Maldonado

J. Compos. Sci. 2021, 5(3), 81; https://doi.org/10.3390/jcs5030081 - 13 Mar 2021

Cited by 17 | Viewed by 2818

Abstract

Different approaches for the simulation of wrinkling during forming of textile reinforcements are presented. It is shown that 3D finite element modeling requires the consideration of an additional bending stiffness of the fibers. In shell-type modeling, the bending stiffness is important because it [...] Read more.

Different approaches for the simulation of wrinkling during forming of textile reinforcements are presented. It is shown that 3D finite element modeling requires the consideration of an additional bending stiffness of the fibers. In shell-type modeling, the bending stiffness is important because it conditions the size of the wrinkles. Different methods to take into account the bending stiffness independently of the tensile stiffness are presented. The onset and development of wrinkles during forming is a global problem that concerns all deformation modes. It is shown in examples that the shear locking angle is not sufficient to conclude about the development of wrinkles. This article highlights the two points common to the different cases of wrinkling of continuous fiber textile reinforcements: the quasi-inextensibility of the fibers and the possible slippage between the fibers. It presents and compares different approaches to consider these two aspects. The simulation of the simultaneous forming of multilayered textile reinforcements makes it possible to see the influence of the orientation of different plies which is an important factor with regard to wrinkling. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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21 pages, 9445 KiB

Open AccessArticle

Consolidation and Tow Spreading of Digitally Manufactured Continuous Fiber Reinforced Composites from Thermoplastic Commingled Tow Using a Five-Axis Extrusion System

by Mark E. Bourgeois and Donald W. Radford

J. Compos. Sci. 2021, 5(3), 73; https://doi.org/10.3390/jcs5030073 - 05 Mar 2021

Cited by 3 | Viewed by 1787

Abstract

During the development of digitally manufactured, commingled tow continuous fiber reinforced composites, consolidation force was controlled using a controlled spring force that yielded a repeatable tow width. However, the use of the extruder face to consolidate the material requires that the extruder remain [...] Read more.

During the development of digitally manufactured, commingled tow continuous fiber reinforced composites, consolidation force was controlled using a controlled spring force that yielded a repeatable tow width. However, the use of the extruder face to consolidate the material requires that the extruder remain perpendicular to the placement surface throughout the process. When considering more complex tool contours including sloped surfaces, more than three axes of motion are necessary to maintain the perpendicularity of the extruder tip to the surface. In this effort, a five-axis system is developed and used to demonstrate the ability to consolidate over complex contours. In addition, the nozzle face temperatures required for good consolidation and wetout result in poor tow path fidelity when complex paths are introduced. The implementation of an automated, computer-controlled localized cooling system enables both good wetout and consolidation while also enabling more accurate changes in tow path due to improvements in local tow tack. With the development of the five-axis system it is also shown that the tow width can be adjusted by rotating the existing placement nozzle to angles not equal to 90°. Thus, through a combination of controlled localized cooling and real-time control of the nozzle angle, a possible approach to control of tow width, independent of the tow placement angle and radius of curvature during tow steering, is described. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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22 pages, 6684 KiB

Open AccessArticle

Static Fatigue of SiC/SiC Minicomposites at High Temperatures Up to 1200 °C in Air: Multiscale Approach

by Jacques Lamon and Adrien Laforêt

J. Compos. Sci. 2021, 5(3), 67; https://doi.org/10.3390/jcs5030067 - 28 Feb 2021

Cited by 5 | Viewed by 1702

Abstract

The present paper investigates the static fatigue behavior of Hi-Nicalon fiber-reinforced SiC–SiC minicomposites at high temperatures in the 900–1200 °C range, and under tensile stresses above the proportional limit. The stress–rupture time relation was analyzed with respect to subcritical crack growth in filaments [...] Read more.

The present paper investigates the static fatigue behavior of Hi-Nicalon fiber-reinforced SiC–SiC minicomposites at high temperatures in the 900–1200 °C range, and under tensile stresses above the proportional limit. The stress–rupture time relation was analyzed with respect to subcritical crack growth in filaments and fiber tow fracture. Slow crack growth from flaws located at the surface of filaments is driven by the oxidation of free carbon at the grain boundaries. Lifetime of the reinforcing tows depends on the statistical distribution of filament strength and on structural factors, which are enhanced by temperature increase. The rupture time data were plotted in terms of initial stresses on reinforcing filaments. The effect of temperature and load on the stress–rupture time relation for minicomposites was investigated using results of fractography and predictions of minicomposite lifetime using a model of subcritical growth for critical filaments. The critical filament is the one whose failure by slow crack-growth triggers unstable fracture of the minicomposite. This is identified by the strength–probability relation provided by the cumulative distribution function for filament strength at room temperature. The results were compared to the fatigue behavior of dry tows. The influence of various factors related to oxidation, including multiple failures, load sharing, and variability, was analyzed. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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17 pages, 8392 KiB

Open AccessArticle

Modeling and Simulations of the Sulfur Infiltration in Activated Carbon Fabrics during Composite Cathode Fabrication for Lithium-Sulfur Batteries

by Kyriakos Lasetta, Joseph Paul Baboo and Constantina Lekakou

J. Compos. Sci. 2021, 5(3), 65; https://doi.org/10.3390/jcs5030065 - 25 Feb 2021

Cited by 8 | Viewed by 2298

Abstract

During the manufacture of a composite cathode for lithium-sulfur (Li-S) batteries it is important to realize homogeneous infiltration of a specified amount of sulfur, targeted to be at least 5 mg cm⁻² to achieve good battery performance in terms of high energy [...] Read more.

During the manufacture of a composite cathode for lithium-sulfur (Li-S) batteries it is important to realize homogeneous infiltration of a specified amount of sulfur, targeted to be at least 5 mg cm⁻² to achieve good battery performance in terms of high energy density. A model of the sulfur infiltration is presented in this study, taking into account the pore size distribution of the porous cathode host, phase transitions in sulfur, and formation of different sulfur allotropes, depending on pore size, formation energy and available thermal energy. Simulations of sulfur infiltration into an activated carbon fabric at a hot-plate temperature of 175 °C for two hours predicted a composite cathode with 41 wt% sulfur (8.3 mg cm⁻²), in excellent agreement with the experiment. The pore size distribution of the porous carbon host proved critical for both the extent and form of retained sulfur, where pores below 0.4 nm could not accommodate any sulfur, pores between 0.4 and 0.7 nm retained S₄ and S₆ allotropes, and pores between 0.7 and 1.5 nm contained S₈. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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17 pages, 12279 KiB

Open AccessArticle

A Lamination Model for Pressure-Assisted Sintering of Multilayered Porous Structures

by Zhi-He Jin and Corson L. Cramer

J. Compos. Sci. 2021, 5(2), 53; https://doi.org/10.3390/jcs5020053 - 09 Feb 2021

Cited by 1 | Viewed by 1622

Abstract

This work describes a lamination model for pressure-assisted sintering of thin, multilayered, and porous structures based on the linear viscous constitutive theory of sintering and the classical laminated plate theory of continuum mechanics. A constant out-of-plane normal stress is assumed in the constitutive [...] Read more.

This work describes a lamination model for pressure-assisted sintering of thin, multilayered, and porous structures based on the linear viscous constitutive theory of sintering and the classical laminated plate theory of continuum mechanics. A constant out-of-plane normal stress is assumed in the constitutive relation. The lamination relations between the force/moment resultants and the strain/curvature rates are presented. Numerical simulations were performed for a symmetric tri-layer laminate consisting of a 10% gadolinia doped ceria (Ce_0.9Gd_0.1O_1.95-δ) composite structure, where porous layers were adhered to the top and bottom of a denser layer under uniaxially-applied pressures and the sinter forging conditions. The numerical results show that, compared with free sintering, the applied pressure can significantly reduce the sintering time required to achieve given layer thicknesses and porosities. Unlike free sintering, which results in a monotonic decrease of the laminate in-plane dimension, pressure-assisted sintering may produce an in-plane dimension increase or decrease, depending on the applied pressure and sintering time. Finally, the individual layers in the laminate exhibit different stress characteristics under pressure-assisted sintering. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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16 pages, 8674 KiB

Open AccessArticle

Interactions of Cd²⁺, Co²⁺ and MoO₄²⁻ Ions with Crushed Concrete Fines

by Victoria K. Elmes and Nichola J. Coleman

J. Compos. Sci. 2021, 5(2), 42; https://doi.org/10.3390/jcs5020042 - 01 Feb 2021

Cited by 4 | Viewed by 1874

Abstract

Construction and demolition activities generate approximately two thirds of the world’s waste, with concrete-based demolition material accounting for the largest proportion. Primary aggregates are recovered and reused, although the cement-rich fine fraction is underutilised. In this study, single metal batch sorption experiments confirmed [...] Read more.

Construction and demolition activities generate approximately two thirds of the world’s waste, with concrete-based demolition material accounting for the largest proportion. Primary aggregates are recovered and reused, although the cement-rich fine fraction is underutilised. In this study, single metal batch sorption experiments confirmed that crushed concrete fines (CCF) are an effective sorbent for the maximum exclusion of 45.2 mg g⁻¹ Cd²⁺, 38.4 mg g⁻¹ Co²⁺ and 56.0 mg g⁻¹ MoO₄²⁻ ions from aqueous media. The principal mechanisms of sorption were determined, by scanning electron microscopy of the metal-laden CCF, to be co-precipitation with Ca²⁺ ions released from the cement to form solubility limiting phases. The removal of Co²⁺ and MoO₄²⁻ ions followed a zero-order reaction and that of Cd²⁺ was best described by a pseudo-second-order model. The Langmuir model provided the most appropriate description of the steady state immobilisation of Cd²⁺ and Co²⁺, whereas the removal of MoO₄²⁻ conformed to the Freundlich isotherm. Long equilibration times (>120 h), loose floc formation and high pH are likely to limit the use of CCF in many conventional wastewater treatment applications; although, these properties could be usefully exploited in reactive barriers for the management of contaminated soils, sediments and groundwater. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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12 pages, 25437 KiB

Open AccessArticle

Impact Damage Detection in Composite Beams by Analysis of Non-Linearity under Pulse Excitation

by Gabriela Loi, Maria Cristina Porcu and Francesco Aymerich

J. Compos. Sci. 2021, 5(2), 39; https://doi.org/10.3390/jcs5020039 - 26 Jan 2021

Cited by 7 | Viewed by 2059

Abstract

To detect the presence of damage, many structural health monitoring techniques exploit the nonlinear features that typically affect the otherwise linear dynamic response of structural components with internal defects. One of them is the Scaling Subtraction Method (SSM), which evaluates nonlinear features of [...] Read more.

To detect the presence of damage, many structural health monitoring techniques exploit the nonlinear features that typically affect the otherwise linear dynamic response of structural components with internal defects. One of them is the Scaling Subtraction Method (SSM), which evaluates nonlinear features of the response to a high-amplitude harmonic excitation by subtracting a scaled reference signal. Originally tested on granular materials, the SSM was shown to be effective for composite materials as well. However, the dependence of the technique efficiency on the testing frequency, usually selected among the natural frequencies of the system, may limit its application in practice. This paper investigates the feasibility of applying the SSM through a broadband impulsive excitation, which would avoid the need of a preliminary modal analysis and address the issue of the proper selection of the excitation frequency. A laminated composite beam was tested in intact and damaged conditions under both scaled harmonic excitations of different frequency and broadband impulsive signals of scaled amplitude. Two damage indicators working on the frequency domain were introduced. The results showed a good sensitivity of the SSM to the presence and level of impact damage in composite beams when applied through a broadband impulsive excitation. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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7 pages, 935 KiB

Open AccessArticle

Coefficient of Thermal Expansion of Single-Wall Carbon Nanotube Reinforced Nanocomposites

by Chensong Dong

J. Compos. Sci. 2021, 5(1), 26; https://doi.org/10.3390/jcs5010026 - 14 Jan 2021

Cited by 1 | Viewed by 1753

Abstract

A study on the coefficient of thermal expansion (CTE) of single-wall carbon nanotube (SWCNT)-reinforced nanocomposites is presented in this paper. An interfacial adhesion factor (IAF) is introduced for the purpose of modelling the adhesion between SWCNTs and the matrix. The effective CTE and [...] Read more.

A study on the coefficient of thermal expansion (CTE) of single-wall carbon nanotube (SWCNT)-reinforced nanocomposites is presented in this paper. An interfacial adhesion factor (IAF) is introduced for the purpose of modelling the adhesion between SWCNTs and the matrix. The effective CTE and modulus of SWCNTs are derived using the IAF, and the effective CTE of the nanocomposite is derived by the Mori–Tanaka method. The developed model is validated against experimental data and good agreement is found. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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14 pages, 3439 KiB

Open AccessArticle

Single Wall Carbon Nanotubes/Polypyrrole Composite Thin Film Electrodes: Investigation of Interfacial Ion Exchange Behavior

by Freddy Escobar-Teran, Hubert Perrot and Ozlem Sel

J. Compos. Sci. 2021, 5(1), 25; https://doi.org/10.3390/jcs5010025 - 14 Jan 2021

Cited by 2 | Viewed by 2267

Abstract

Single-wall carbon nanotubes/polypyrrole (SWCNT/PPy) composite thin-film electrodes were prepared by electrodeposition of the pyrrole monomer on a porous network made of SWCNT bundles. Electrode/electrolyte interface, which is intimately related to the pseudocapacitive charge storage behavior, is investigated by using coupled electrogravimetric methods (electrochemical [...] Read more.

Single-wall carbon nanotubes/polypyrrole (SWCNT/PPy) composite thin-film electrodes were prepared by electrodeposition of the pyrrole monomer on a porous network made of SWCNT bundles. Electrode/electrolyte interface, which is intimately related to the pseudocapacitive charge storage behavior, is investigated by using coupled electrogravimetric methods (electrochemical quartz crystal microbalance (EQCM) and its coupling with electrochemical impedance spectroscopy, Ac-electrogravimetry), in a 0.5 M NaCl electrolyte (pH = 7). Our results show that the range of usable potential is greater for composite SWCNT/PPy films than for SWCNT films, which should allow a higher storage capacity to be obtained. This effect is also confirmed by mass variation measurements via EQCM. The mass change (corresponding to the amount of (co)electroadsorbed species) obtained with composite SWCNT/PPy films is four times greater than that observed for pristine SWCNT films if the same potential range is examined. The permselectivity is also greatly improved in the case of composite SWCNT/PPy films compared to SWCNT films; the former shows mainly cation exchange preference. The quantities of anions estimated by Ac-electrogravimetric measurements are much lower in the case of composites. This corroborates the better permselectivity of these composite SWCNT/PPy films even with a moderate amount of PPy. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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29 pages, 10676 KiB

Open AccessArticle

Ballistic Penetration Analysis of Soft Laminated Composites Using Sublaminate Mesoscale Modeling

by Raz Chricker, Shaul Mustacchi, Eyass Massarwa, Rami Eliasi, Jacob Aboudi and Rami Haj-Ali

J. Compos. Sci. 2021, 5(1), 21; https://doi.org/10.3390/jcs5010021 - 08 Jan 2021

Cited by 5 | Viewed by 2825

Abstract

Ballistic impact mitigation requires the development of protective armor applications from composite material systems with good energy absorption and penetration resistance against threats, e.g., metallic projectiles. In this aim, high-strength and high-stiffness soft fibrous composite materials (such as ultra-high molecular weight polyethylene—UHMWPE) are [...] Read more.

Ballistic impact mitigation requires the development of protective armor applications from composite material systems with good energy absorption and penetration resistance against threats, e.g., metallic projectiles. In this aim, high-strength and high-stiffness soft fibrous composite materials (such as ultra-high molecular weight polyethylene—UHMWPE) are often used. The high specific strength feature is one of the main reasons for using these soft composite systems in ballistic impact applications. In the present investigation, experimental and computational finite element (FE) studies were carried out to investigate the ballistic behaviors of these soft layered composite targets. To this end, a new FE multi-scale analysis framework for ballistic simulations is offered. The proposed analysis presents a new meso-scale sublaminate material model, which is applied to Dyneema^® cross-ply laminate in order to predict its behavior under ballistic impact. The sublaminate model is implemented within an explicit dynamic FE code to simulate the continuum response in each element. The sublaminate model assumes a through-thickness periodic stacking of repeated cross-ply configuration. In addition, a cohesive layer is introduced in the sublaminate model in order to simulate the delamination effect leading to the subsequent degradation and deletion of the elements. This new approach eliminates the widely used costly computational approach of using explicit cohesive elements installed at pre-specified potential delamination paths between the layers. Furthermore, in-plane damage modes (such as fiber tensile, and out-of-plane shearing) are also accounted for by employing failure criteria and strain-softening. The obtained quantitative results of ballistic impact simulations show good correlation when compared to a relatively wide range of experiments. Moreover, the simulations include evidence of capturing the main energy absorption mechanisms under high-velocity impact. The proposed modeling approach can be used as a useful armor design tool. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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14 pages, 6853 KiB

Open AccessArticle

A Raman Spectroscopic Analysis of Polymer Membranes with Graphene Oxide and Reduced Graphene Oxide

by Anna Kołodziej, Elżbieta Długoń, Małgorzata Świętek, Magdalena Ziąbka, Emilia Dawiec, Maciej Gubernat, Marek Michalec and Aleksandra Wesełucha-Birczyńska

J. Compos. Sci. 2021, 5(1), 20; https://doi.org/10.3390/jcs5010020 - 08 Jan 2021

Cited by 31 | Viewed by 4263

Abstract

Nowadays, despite significant advances in the field of biomaterials for tissue engineering applications, novel bone substituents still need refinement so they can be successfully implemented into the medical treatment of bone fractures. Generally, a scaffold made of synthetic polymer blended with nanofillers was [...] Read more.

Nowadays, despite significant advances in the field of biomaterials for tissue engineering applications, novel bone substituents still need refinement so they can be successfully implemented into the medical treatment of bone fractures. Generally, a scaffold made of synthetic polymer blended with nanofillers was proven to be a very promising biomaterial for tissue engineering, however the choice of components for the said scaffold remains questionable. The objects of the presented study were novel composites consisting of poly(ε-caprolactone) (PCL) and two types of graphene materials: graphene oxide (GO) and partially reduced graphene oxide (rGO). The technique of choice, that was used to characterize the obtained composites, was Raman micro-spectroscopy. It revealed that the composite PCL/GO differs substantially from the PCL/rGO composite. The incorporation of the GO particles into the polymer influenced the structure organisation of the polymeric matrix more significantly than rGO. The crystallinity parameters confirmed that the level of crystallinity is generally higher in the PCL/GO membrane in comparison to PCL/rGO (and even in raw PCL) that leads to the conclusion that the GO acts as a nucleation agent enhancing the crystallization of PCL. Interestingly, the characteristics of the studied nanofillers, for example: the level of the organisation (D/G ratio) and the in-plane size of the nano-crystallites (L_a) almost do not differ. However, they have an ability to influence polymeric matrix differently. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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11 pages, 4035 KiB

Open AccessArticle

Designing Hierarchical Honeycombs to Mimic the Mechanical Behaviour of Composites

by Ziyue Yang and Parvez Alam

J. Compos. Sci. 2021, 5(1), 17; https://doi.org/10.3390/jcs5010017 - 07 Jan 2021

Cited by 3 | Viewed by 2330

Abstract

Honeycombs are used ubiquitously in engineering applications as they have excellent out-of-plane strength and stiffness properties with respect to weight. This paper considers the properties of honeycombs in the in-plane direction, a direction that is significantly weaker and less stiff than the out-of-plane [...] Read more.

Honeycombs are used ubiquitously in engineering applications as they have excellent out-of-plane strength and stiffness properties with respect to weight. This paper considers the properties of honeycombs in the in-plane direction, a direction that is significantly weaker and less stiff than the out-of-plane direction. We assess how judiciously locating structural hierarchy within a honeycomb array can be a geometric design principle with direct consequences on the mechanical behaviour of the honeycomb. Here, we use finite element methods to design reinforced honeycomb mechanical metamaterials that mimic the mechanical behaviour of unidirectional fibre reinforced composites. We specifically incorporate structural hierarchy within hollow honeycomb cells to create mechanical metamaterial pseudo-composites, where the hierarchical parts are pseudo-fibres, and the hollow parts are the pseudo-matrix. We find that pseudo-fibre contribution coefficients are higher than the fibre contribution coefficient of carbon fibre reinforced plastics (CFRP). We also find that the elastic modulus of unidirectional pseudo-composites can be predicted using the (Voigt model) rule of mixtures with a good level of accuracy. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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20 pages, 6465 KiB

Open AccessArticle

Enhanced X-ray Visibility of Shape Memory Polymer Foam Using Iodine Motifs and Tantalum Microparticles

by Lindy K. Jang, Landon D. Nash, Grace K. Fletcher, Thomas Cheung, Andrew Soewito and Duncan J. Maitland

J. Compos. Sci. 2021, 5(1), 14; https://doi.org/10.3390/jcs5010014 - 06 Jan 2021

Cited by 2 | Viewed by 2200

Abstract

Shape memory polymer (SMP) foams are porous materials with high surface area and large volumetric expansion capabilities that are well suited for endovascular occlusion applications, including brain aneurysm embolization. However, many polyurethane SMP foams are inherently radiolucent when X-ray visibility is required to [...] Read more.

Shape memory polymer (SMP) foams are porous materials with high surface area and large volumetric expansion capabilities that are well suited for endovascular occlusion applications, including brain aneurysm embolization. However, many polyurethane SMP foams are inherently radiolucent when X-ray visibility is required to ensure the safe delivery of the foam to the targeted aneurysm site using fluoroscopy. Here, highly radio-dense tantalum microparticles were added to a previously reported triiodobenzene-containing SMP foam (ATIPA foam) premix to fabricate ATIPA foam-tantalum composites (AT_T). The AT_T foams showed comparable glass transition temperatures, faster expansion profiles, increased X-ray visibility, good cytocompatibility, and faster oxidative degradation compared to the control ATIPA foam without tantalum. The mechanical properties were improved up to 4 vol% tantalum and the X-ray visibility was most appropriate for the 2 vol% (AT_2%T) and 4 vol% (AT_4%T) tantalum foams. E-beam sterilization did not impair the critical properties of the ATIPA foams. Overall, AT_2%T was the optimal foam composition for neurovascular prototypes due to its high oxidative stability in vitro compared to previous low-density SMP foams. The AT_T foams are very promising materials with high toughness and sufficient X-ray visibility for use as neurovascular embolization devices. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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8 pages, 2941 KiB

Open AccessArticle

Interfacial Stabilization of a Graphene-Wrapped Cu₂S Anode for High-Performance Sodium-Ion Batteries via Atomic Layer Deposition

by Jiyu Cai, Zonghai Chen and Xiangbo Meng

J. Compos. Sci. 2020, 4(4), 184; https://doi.org/10.3390/jcs4040184 - 08 Dec 2020

Viewed by 1930

Abstract

Sodium-ion batteries (SIBs) have attracted increasing attention for storing renewable clean energy, owing to their cost-effectiveness. Nonetheless, SIBs still remain significant challenges in terms of the availability of suitable anode materials with high capacities and good rate capabilities. Our previous work has developed [...] Read more.

Sodium-ion batteries (SIBs) have attracted increasing attention for storing renewable clean energy, owing to their cost-effectiveness. Nonetheless, SIBs still remain significant challenges in terms of the availability of suitable anode materials with high capacities and good rate capabilities. Our previous work has developed and verified that Cu₂S wrapped by nitrogen-doped graphene (i.e., Cu₂S@NG composite), as an anode in SIBs, could exhibit a superior performance with ultralong cyclability and excellent rate capability, mainly due to the multifunctional roles of NG. However, the Cu₂S@NG anode still suffers from continuous parasitic reactions at low potentials, causing a rapid performance deterioration. In this study, we investigated the effects of a conformal Al₂O₃ coating via atomic layer deposition (ALD) on the interfacial stability of the Cu₂S@NG anode. As a consequence, the ALD-coated Cu₂S@NG electrode can deliver a high capacity of 374 mAh g⁻¹ at a current density of 100 mA g⁻¹ and achieve a capacity retention of ~100% at different rates. This work verified that surface modification via ALD is a viable route for improving SIBs’ performances. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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17 pages, 9330 KiB

Open AccessArticle

Automated Identification of Defect Morphology and Spatial Distribution in Woven Composites

by Anna Madra, Dan-Thuy Van-Pham, Minh-Tri Nguyen, Chanh-Nghiem Nguyen, Piotr Breitkopf and François Trochu

J. Compos. Sci. 2020, 4(4), 178; https://doi.org/10.3390/jcs4040178 - 27 Nov 2020

Cited by 5 | Viewed by 2157

Abstract

The performance of heterogeneous materials, for example, woven composites, does not always reach the predicted theoretical potential. This is caused by defects, such as residual voids introduced during the manufacturing process. A machine learning-based methodology is proposed to determine the morphology and spatial [...] Read more.

The performance of heterogeneous materials, for example, woven composites, does not always reach the predicted theoretical potential. This is caused by defects, such as residual voids introduced during the manufacturing process. A machine learning-based methodology is proposed to determine the morphology and spatial distribution of defects in composites based on X-ray microtomographic scans of the microstructure. A concept of defect "genome" is introduced as an indicator of the overall state of defects in the material, enabling a quick comparison of specimens manufactured under different conditions. The approach is illustrated for thermoplastic composites with unidirectional banana fiber reinforcement. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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18 pages, 5566 KiB

Open AccessArticle

Performance of Composite Metal Foam Armors against Various Threat Sizes

by Jacob Marx, Marc Portanova and Afsaneh Rabiei

J. Compos. Sci. 2020, 4(4), 176; https://doi.org/10.3390/jcs4040176 - 23 Nov 2020

Cited by 13 | Viewed by 7235

Abstract

The ballistic capabilities of composite metal foam (CMF) armors were experimentally tested against a 14.5 × 114 mm B32 armor-piercing incendiary (API) and compared to various sizes of armor-piercing (AP) ballistic threats, ranging from a 7.62 to 12.7 mm. Three different arrangements of [...] Read more.

The ballistic capabilities of composite metal foam (CMF) armors were experimentally tested against a 14.5 × 114 mm B32 armor-piercing incendiary (API) and compared to various sizes of armor-piercing (AP) ballistic threats, ranging from a 7.62 to 12.7 mm. Three different arrangements of layered hard armors were designed and manufactured using ceramic faceplates (in one layer, two layers or multiple tiles), a combination of ceramic and steel face sheets, with a single-layered CMF core, and a thin aluminum backing. The performance of various CMF armor designs against the 14.5 mm rounds are compared to each other and to the performance of the rolled homogeneous armor standard to identify the most efficient design for further investigations. The percentage of kinetic energy absorbed by the CMF layer in various armor arrangements and in tests against various threat sizes was calculated and compared. It appears that the larger the threat size, the more efficient the CMF layer will be due to a greater number of hollow metal spheres that are engaged in absorbing the impact energy. The results from this study will help to model and predict the performance of CMF armors against various threat sizes and impact energies. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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11 pages, 227 KiB

Open AccessCommunication

Poly(Vinyl Alcohol) Recent Contributions to Engineering and Medicine

by Dorel Feldman

J. Compos. Sci. 2020, 4(4), 175; https://doi.org/10.3390/jcs4040175 - 23 Nov 2020

Cited by 35 | Viewed by 4098

Abstract

Poly(vinyl alcohol) (PVA) is a thermoplastic synthetic polymer, which, unlike many synthetic polymers, is not obtained by polymerization, but by hydrolysis of poly(vinyl acetate) (PVAc). Due to the presence of hydroxylic groups, hydrophilic polymers such as PVA and its composites made mainly with [...] Read more.

Poly(vinyl alcohol) (PVA) is a thermoplastic synthetic polymer, which, unlike many synthetic polymers, is not obtained by polymerization, but by hydrolysis of poly(vinyl acetate) (PVAc). Due to the presence of hydroxylic groups, hydrophilic polymers such as PVA and its composites made mainly with biopolymers are used for producing hydrogels that possess interesting morphological and physico-mechanical features. PVA hydrogels and other PVA composites are studied in light of their numerous application for electrical film membranes for chemical separation, element and dye removal, adsorption of metal ions, fuel cells, and packaging. Aside from applications in the engineering field, PVA, like other synthetic polymers, has applications in medicine and biological areas and has become one of the principal objectives of the researchers in the polymer domain. The review presents a few recent applications of PVA composites and contributions related to tissue engineering (repair and regeneration), drug carriers, and wound healing. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

22 pages, 5046 KiB

Open AccessArticle

Polydopamine-Coated Paraffin Microcapsules as a Multifunctional Filler Enhancing Thermal and Mechanical Performance of a Flexible Epoxy Resin

by Giulia Fredi, Cordelia Zimmerer, Christina Scheffler and Alessandro Pegoretti

J. Compos. Sci. 2020, 4(4), 174; https://doi.org/10.3390/jcs4040174 - 22 Nov 2020

Cited by 12 | Viewed by 3132

Abstract

This work focuses on flexible epoxy (EP) composites containing various amounts of neat and polydopamine (PDA)-coated paraffin microcapsules as a phase change material (PCM), which have potential applications as adhesives or flexible interfaces with thermal management capability for electronics or other high-value-added fields. [...] Read more.

This work focuses on flexible epoxy (EP) composites containing various amounts of neat and polydopamine (PDA)-coated paraffin microcapsules as a phase change material (PCM), which have potential applications as adhesives or flexible interfaces with thermal management capability for electronics or other high-value-added fields. After PDA modification, the surface of PDA-coated capsules (MC-PDA) becomes rough with a globular appearance, and the PDA layer enhances the adhesion with the surrounding epoxy matrix, as shown by scanning electron microscopy. PDA deposition parameters have been successfully tuned to obtain a PDA layer with a thickness of 53 ± 8 nm, and the total PDA mass in MC-PDA is only 2.2 wt %, considerably lower than previous results. This accounts for the fact that the phase change enthalpy of MC-PDA is only marginally lower than that of neat microcapsules (MC), being 221.1 J/g and 227.7 J/g, respectively. Differential scanning calorimetry shows that the phase change enthalpy of the prepared composites increases with the capsule content (up to 87.8 J/g) and that the enthalpy of the composites containing MC-PDA is comparable to that of the composites with MC. Dynamic mechanical analysis evidences a decreasing step in the storage modulus of all composites at the glass transition of the EP phase, but no additional signals are detected at the PCM melting. PCM addition positively contributes to the storage modulus both at room temperature and above

T_{g}

of the EP phase, and this effect is more evident for composites containing MC-PDA. As the capsule content increases, the mechanical properties of the host EP matrix also increase in terms of elastic modulus (up to +195%), tensile strength (up to +42%), Shore D hardness (up to +36%), and creep compliance (down to −54% at 60 min). These effects are more evident for composites containing MC-PDA due to the enhanced interfacial adhesion. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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15 pages, 3321 KiB

Open AccessArticle

Thermal Transformation of End-of-Life Latex to Valuable Materials

by Enamul Haque, Farshid Pahlevani, Narjes Gorjizadeh, Rumana Hossain and Veena Sahajwalla

J. Compos. Sci. 2020, 4(4), 166; https://doi.org/10.3390/jcs4040166 - 04 Nov 2020

Cited by 1 | Viewed by 2589

Abstract

Recent studies have demonstrated that carbon nanomaterials have huge potential in composite applications, but there is a continuous quest for identifying the most viable technique for producing this material. In this study, the possibility of using an innovative approach for the synthesis of [...] Read more.

Recent studies have demonstrated that carbon nanomaterials have huge potential in composite applications, but there is a continuous quest for identifying the most viable technique for producing this material. In this study, the possibility of using an innovative approach for the synthesis of value-added carbon nanomaterials and green gases from end-of-life soft mattress materials (latex) was investigated. Thermogravimetric analysis (TGA) was used to determine the thermal degradation of latex. Quantitative gas analysis at three different temperatures by infrared spectroscopy (IR) suggested that small gas molecules, especially CH₄, could be produced at a higher temperature. The carbon residues produced after gas analysis were characterised by XRD, SEM, TEM, XPS, and Raman spectroscopy, suggesting the possibility of direct synthesis of carbon nanomaterials from waste latex. These carbon materials have Na, Zn, Si, and K in their structure, and further study is needed for understanding the effect of these elements on composite properties. Our study demonstrated that heat treatment of waste latex at 1000 °C for 15 min produced carbon materials, which contained 7–16% S and 1.2–2% N, and gases, such as CH₄, could be synthesised. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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26 pages, 1471 KiB

Open AccessArticle

Strong and Weak Formulations of a Mixed Higher-Order Shear Deformation Theory for the Static Analysis of Functionally Graded Beams under Thermo-Mechanical Loads

by Chih-Ping Wu and Zhan-Rong Xu

J. Compos. Sci. 2020, 4(4), 158; https://doi.org/10.3390/jcs4040158 - 23 Oct 2020

Cited by 4 | Viewed by 1609

Abstract

The strong and weak formulations of a mixed layer-wise (LW) higher-order shear deformation theory (HSDT) are developed for the static analysis of functionally graded (FG) beams under various boundary conditions subjected to thermo-mechanical loads. The material properties of the FG beam are assumed [...] Read more.

The strong and weak formulations of a mixed layer-wise (LW) higher-order shear deformation theory (HSDT) are developed for the static analysis of functionally graded (FG) beams under various boundary conditions subjected to thermo-mechanical loads. The material properties of the FG beam are assumed to obey a power-law distribution of the volume fractions of the constituents through the thickness of the FG beam, for which the effective material properties are estimated using the rule of mixtures, or it is directly assumed that the effective material properties of the FG beam obey an exponential function distribution along the thickness direction of the FG beam. The results shown in the numerical examples indicate that the mixed LW HSDT solutions for elastic and thermal field variables are in excellent agreement with the accurate solutions available in the literature. A parametric study related to various effects on the coupled thermo-mechanical behavior of FG beams is carried out, including the aspect ratio, the material-property gradient index, and different boundary conditions. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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17 pages, 1940 KiB

Open AccessArticle

The Maximum Stress Failure Criterion and the Maximum Strain Failure Criterion: Their Unification and Rationalization

by Shuguang Li

J. Compos. Sci. 2020, 4(4), 157; https://doi.org/10.3390/jcs4040157 - 22 Oct 2020

Cited by 16 | Viewed by 8133

Abstract

The maximum strain failure criterion is unified with the maximum stress failure criterion, after exploring the implications of two considerations responsible for this: (1) the failure strains for the direct strain components employed in the maximum strain criterion are all defined under uniaxial [...] Read more.

The maximum strain failure criterion is unified with the maximum stress failure criterion, after exploring the implications of two considerations responsible for this: (1) the failure strains for the direct strain components employed in the maximum strain criterion are all defined under uniaxial stress states, not uniaxial strain states, and (2) the contributions to the strain in a direction as a result of the Poisson effect do not contribute to the failure of the material in that direction. Incorporating these considerations into the maximum strain criterion, the maximum stress criterion is reproduced. For 3D stress/strain state applications primarily, the unified maximum stress/strain criterion is then subjected to further rationalization in the context of transversely isotropic materials by eliminating the treatments that undermine the objectivity of the failure criterion. The criterion is then applied based on the maximum and minimum direct stresses, the maximum transverse shear stress and the maximum longitudinal shear stress as the invariants of the stress state, instead of the conventional stress components directly. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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20 pages, 4043 KiB

Open AccessArticle

From Magneto-Dielectric Biocomposite Films to Microstrip Antenna Devices

by Fernando Lima de Menezes, Davino Machado Andrade Neto, Maria do Livramento Linhares Rodrigues, Helder Levi Silva Lima, Denis Valony Martins Paiva, Marcelo Antônio Santos da Silva, Lillian Maria Uchôa Dutra Fechine, Antônio Sérgio Bezerra Sombra, Rafael Melo Freire, Juliano Casagrande Denardin, Morsyleide de Freitas Rosa, Men de Sá Moreira de Souza Filho, Selma Elaine Mazzetto and Pierre Basílio Almeida Fechine

J. Compos. Sci. 2020, 4(4), 144; https://doi.org/10.3390/jcs4040144 - 24 Sep 2020

Cited by 9 | Viewed by 2789

Abstract

Magneto-dielectric composites are interesting advanced materials principally due to their potential applications in electronic fields, such as in microstrip antennas substrates. In this work, we developed superparamagnetic polymer-based films using the biopolymeric matrices chitosan (Ch), cellulose (BC) and collagen (Col). For this proposal, [...] Read more.

Magneto-dielectric composites are interesting advanced materials principally due to their potential applications in electronic fields, such as in microstrip antennas substrates. In this work, we developed superparamagnetic polymer-based films using the biopolymeric matrices chitosan (Ch), cellulose (BC) and collagen (Col). For this proposal, we synthesized superparamagnetic iron oxide nanoparticles (SPIONs) functionalized with polyethyleneimine with a cheap method using sonochemistry. Further, the SPIONs were dispersed into polymer matrices and the composites were evaluated regarding morphology, thermal, dielectric and magnetic properties and their application as microstrip antennas substrates. Microscopically, all tested films presented a uniform dispersion profile, principally due to polyethyleneimine coating. Under an operating frequency (f_o) of 4.45 GHz, Ch, BC and Col-based SPION substrates showed moderate dielectric constant (ε′) values in the range of 5.2–8.3, 6.7–8.4 and 5.9–9.1, respectively. Furthermore, the prepared films showed no hysteresis loop, thereby providing evidence of superparamagnetism. The microstrip antennas showed considerable bandwidths (3.37–6.34%) and a return loss lower than −10 dB. Besides, the f_o were modulated according to the addition of SPIONs, varying in the range of 4.69–5.55, 4.63–5.18 and 4.93–5.44 GHz, for Ch, BC and Col-based substrates, respectively. Moreover, considering best modulation of ε′ and f_o, the Ch-based SPION film showed the most suitable profile as a microstrip antenna substrate. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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25 pages, 3970 KiB

Open AccessArticle

Tensile and Compressive Behavior in the Experimental Tests for PLA Specimens Produced via Fused Deposition Modelling Technique

by Salvatore Brischetto and Roberto Torre

J. Compos. Sci. 2020, 4(3), 140; https://doi.org/10.3390/jcs4030140 - 18 Sep 2020

Cited by 43 | Viewed by 5147

Abstract

In this paper, polymeric specimens are produced via the Fused Deposition Modelling (FDM) technique. Then, experimental tensile and compression tests are conducted to evaluate the main mechanical properties of elements made of PolyLacticAcid (PLA) material. A standardized characterization test method for FDM 3D [...] Read more.

In this paper, polymeric specimens are produced via the Fused Deposition Modelling (FDM) technique. Then, experimental tensile and compression tests are conducted to evaluate the main mechanical properties of elements made of PolyLacticAcid (PLA) material. A standardized characterization test method for FDM 3D printed polymers has not been developed yet. For this reason, the ASTM D695 (usually employed for polymers produced via classical methods) has been here employed for FDM 3D printed polymers after opportune modifications suggested by appropriate experimental checks. A statistical analysis is performed on the geometrical data of the specimens to evaluate the machine process employed for the 3D printing. A capability analysis is also conducted on the mechanical properties (obtained from the experimental tests) in order to calculate acceptable limits useful for possible structural analyses. The Young modulus, the proportional limit and the maximum strength here defined for PLA specimens allow to confirm the different behavior of FDM printed PLA material in tensile and compressive state. These differences and the calculated acceptable limits for the found mechanical properties must be considered when this technology will be employed for the design of small structural objects made of PLA, as in the present study, or ABS (Acrilonitrile Butadiene Stirene). From the statistical and capability analysis, the employed printing process appears as quite stable and replicable. These types of research together with other similar ones that will be conducted in the future will allow to use polymeric materials and the FDM technique to produce small structural elements and also to carry out the appropriate verifications. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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11 pages, 4235 KiB

Open AccessArticle

The Mechanical and Material Designs of Composite Ju|’hoansi Arrowheads

by Courtney Archer, Iain Campbell, Fraser Cheyne, Amos Lim Jun Meng, Csongor Senanszky, Dimitrios Mamalis, Colin Robert and Parvez Alam

J. Compos. Sci. 2020, 4(3), 139; https://doi.org/10.3390/jcs4030139 - 18 Sep 2020

Cited by 4 | Viewed by 2843 | Correction

Abstract

In this paper, we elucidate the composite engineering design skills of the Kalahari Ju|’hoansi (San) people, developed over at least tens of thousands of years. In particular, we show that the mechanical and physical properties of materials used by the Ju|’hoansi in the [...] Read more.

In this paper, we elucidate the composite engineering design skills of the Kalahari Ju|’hoansi (San) people, developed over at least tens of thousands of years. In particular, we show that the mechanical and physical properties of materials used by the Ju|’hoansi in the design of arrowheads are intimately linked to their unique geometrical and composite designs. The Ju|’hoansi arrowheads have evolved to become complex engineered units with distinct function-specific purpose. We demonstrate herein that the geometrical designs of the arrowheads are optimised with respect to the material used. We furthermore verify the veracity of the Ju|’hoansi claim that their composite link-shafts are designed to break off leaving the arrowhead in the animal and the remaining parts of the arrow intact, reusable and easily retrievable. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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18 pages, 4908 KiB

Open AccessArticle

Thermoplastic Polyurethane/Lead Zirconate Titanate/Carbon Nanotube Composites with Very High Dielectric Permittivity and Low Dielectric Loss

by Gayaneh Petrossian, Nahal Aliheidari and Amir Ameli

J. Compos. Sci. 2020, 4(3), 137; https://doi.org/10.3390/jcs4030137 - 17 Sep 2020

Cited by 12 | Viewed by 2973

Abstract

Ternary composites of flexible thermoplastic polyurethane (TPU), lead zirconate titanate (PZT), and multiwalled carbon nanotubes (MWCNTs) with very high dielectric permittivity (ε_r) and low dielectric loss (tan δ) are reported. To assess the evolution of dielectric properties with the interactions [...] Read more.

Ternary composites of flexible thermoplastic polyurethane (TPU), lead zirconate titanate (PZT), and multiwalled carbon nanotubes (MWCNTs) with very high dielectric permittivity (ε_r) and low dielectric loss (tan δ) are reported. To assess the evolution of dielectric properties with the interactions between conductive and dielectric fillers, composites were designed with a range of content for PZT (0–30 vol%) and MWCNT (0–1 vol%). The microstructure was composed of PZT-rich and segregated MWCNT-rich regions, which could effectively prevent the formation of macroscopic MWCNT conductive networks and thus reduce the high ohmic loss. Therefore, ε_r increased by a maximum of tenfold, reaching up to 166 by the addition of up to 1 vol% MWCNT to TPU/PZT. More importantly, tan δ remained relatively unchanged at 0.06–0.08, a similar range to that of pure TPU. ε_r/tan δ ratio reached 2870 at TPU/30 vol% PZT/0.5 vol% MWCNT, exceeding most of the reported values. This work demonstrates the potential of three-phase polymer/conductive filler/dielectric filler composites for efficient charge storage applications. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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13 pages, 5764 KiB

Open AccessArticle

Effect of Chemical Treatment on Thermal Properties of Jute Fiber Used in Polymer Composites

by Sweety Shahinur, Mahbub Hasan, Qumrul Ahsan and Julfikar Haider

J. Compos. Sci. 2020, 4(3), 132; https://doi.org/10.3390/jcs4030132 - 09 Sep 2020

Cited by 31 | Viewed by 4610

Abstract

In recent years, natural fibers, such as jute has gained significant research interest in order to fabricate fiber reinforced polymer composites. Chemical treatments are generally carried out on the raw fibers for making composites with improved properties. From a composite manufacturing point of [...] Read more.

In recent years, natural fibers, such as jute has gained significant research interest in order to fabricate fiber reinforced polymer composites. Chemical treatments are generally carried out on the raw fibers for making composites with improved properties. From a composite manufacturing point of view, it is important to understand how the treatments can affect the thermal properties of the jute fiber. In the present research, the effects of rot-retardant, fire-retardant and water-retardant treatments on thermal properties of the jute fiber were investigated. Fiber samples were collected from the middle portion of whole jute fiber. Thermo-gravimetric analysis (TGA) and differential scanning calorimetric (DSC) analysis were subsequently conducted on the jute fiber for thermal characterization. The results demonstrated a lower thermal decomposition temperature in the case of fire-retardant treated jute fiber but higher residue at above 400 °C, as compared to the raw and other treated fibers. In general, it was found that chemically treated fibers absorbed less heat, in contrast to the raw jute fiber and heat flow became negative in all cases of the treated fibers. This study provides important information about the thermal properties of the treated jute fibers for manufacturing polymer-based composite materials. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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14 pages, 5589 KiB

Open AccessArticle

Investigations on Physico-Mechanical and Spectral Studies of Zn²⁺ Doped P₂O₅-Based Bioglass System

by M. Mohan Babu, P. Syam Prasad, S. Hima Bindu, A. Prasad, P. Venkateswara Rao, Nibu Putenpurayil Govindan, N. Veeraiah and Mutlu Özcan

J. Compos. Sci. 2020, 4(3), 129; https://doi.org/10.3390/jcs4030129 - 04 Sep 2020

Cited by 9 | Viewed by 2517

Abstract

ZnO incorporated phosphate based bioglasses with the composition xZnO–22Na₂O–24CaO–(54-X)P₂O₅ (where X = 2, 4, 6, 8, 10 mol%) were developed by melt-quenching process. The physical, thermal and other structural properties of the glasses were studied in detail. By [...] Read more.

ZnO incorporated phosphate based bioglasses with the composition xZnO–22Na₂O–24CaO–(54-X)P₂O₅ (where X = 2, 4, 6, 8, 10 mol%) were developed by melt-quenching process. The physical, thermal and other structural properties of the glasses were studied in detail. By employing various characterization techniques such as X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) in addition to the energy dispersion spectroscopy (EDS), and Raman spectroscopy, the structural properties were analyzed. Interestingly, physical, thermal and mechanical properties were enhanced with the increasing content of zinc oxide up to 8 mol%, due to the presence of more ionic nature of P–O–Zn bonds than P–O–P bonds in the glass network. The FTIR and Raman analysis revealed the evolution of the phosphate network with increasing zinc concentration and leads to progressive depolymerisation of the glass network. The obtained results from the physical and structural properties of these zinc added calcium phosphate glasses support their potential to use as bone implant applications. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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19 pages, 3818 KiB

Open AccessArticle

Variable Stiffness Composites: Optimal Design Studies

by Filipe Eduardo Correia Marques, Ana Filipa Santos da Mota and Maria Amélia Ramos Loja

J. Compos. Sci. 2020, 4(2), 80; https://doi.org/10.3390/jcs4020080 - 24 Jun 2020

Cited by 12 | Viewed by 2042

Abstract

This research work has two main objectives, being the first related to the characterization of variable stiffness composite plates’ behavior by carrying out a comprehensive set of analyses. The second objective aims at obtaining the optimal fiber paths, hence the characteristic angles associated [...] Read more.

This research work has two main objectives, being the first related to the characterization of variable stiffness composite plates’ behavior by carrying out a comprehensive set of analyses. The second objective aims at obtaining the optimal fiber paths, hence the characteristic angles associated to its definition, that yield maximum fundamental frequencies, maximum critical buckling loads, or minimum transverse deflections, both for a single ply and for a three-ply variable stiffness composite. To these purposes one considered the use of the first order shear deformation theory in connection to an adaptive single objective method. From the optimization studies performed it was possible to conclude that significant behavior improvements may be achieved by using variable stiffness composites. Hence, for simply supported three-ply laminates which were the cases where a major impact can be observed, it was possible to obtain a maximum transverse deflection decrease of 11.26%, a fundamental frequency increase of 5.61%, and a buckling load increase of 51.13% and 58.01% for the uniaxial and biaxial load respectively. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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25 pages, 5260 KiB

Open AccessArticle

Peridynamic Mindlin Plate Formulation for Functionally Graded Materials

by Zhenghao Yang, Erkan Oterkus and Selda Oterkus

J. Compos. Sci. 2020, 4(2), 76; https://doi.org/10.3390/jcs4020076 - 19 Jun 2020

Cited by 3 | Viewed by 2160

Abstract

In this study, a new peridynamic Mindlin plate formulation is presented which is suitable for the analysis of functionally graded materials. The governing equations of peridynamic formulation are obtained by using Euler-Lagrange equations in conjunction with Taylor’s expansion. To validate the new formulation, [...] Read more.

In this study, a new peridynamic Mindlin plate formulation is presented which is suitable for the analysis of functionally graded materials. The governing equations of peridynamic formulation are obtained by using Euler-Lagrange equations in conjunction with Taylor’s expansion. To validate the new formulation, three different numerical benchmark problems are considered for a Mindlin plate subjected to simply supported, fully clamped and mixed (clamped-simply supported) boundary conditions. Peridynamic results are compared against results from finite element analysis and a good agreement is observed between the two methods. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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12 pages, 4507 KiB

Open AccessArticle

Surface Modification of Flax Fibers for Manufacture of Engineering Thermoplastic Biocomposites

by Madina Shamsuyeva, Boon Peng Chang, Natalie Vellguth, Manjusri Misra, Amar Mohanty and Hans-Josef Endres

J. Compos. Sci. 2020, 4(2), 64; https://doi.org/10.3390/jcs4020064 - 01 Jun 2020

Cited by 9 | Viewed by 3226

Abstract

The aim of this feasibility study is to develop application-oriented natural fiber-reinforced biocomposites with improved mechanical and durability performance. The biocomposites were manufactured via a film-stacking process of epoxy-coated flax textiles and polyamide 6 (PA6). The fabricated biocomposites were subjected to thermo-oxidative ageing [...] Read more.

The aim of this feasibility study is to develop application-oriented natural fiber-reinforced biocomposites with improved mechanical and durability performance. The biocomposites were manufactured via a film-stacking process of epoxy-coated flax textiles and polyamide 6 (PA6). The fabricated biocomposites were subjected to thermo-oxidative ageing for 250, 500 and 1000 h and tested with regard to tensile properties. The results show that the biocomposites with epoxy-coated flax fibers possess considerably higher tensile properties compared with the reference specimens under all tested conditions. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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20 pages, 7223 KiB

Open AccessArticle

Four Point Flexural Response of Acrylonitrile–Butadiene–Styrene

by Gurpinder S. Dhaliwal and Mehmet Akif Dundar

J. Compos. Sci. 2020, 4(2), 63; https://doi.org/10.3390/jcs4020063 - 31 May 2020

Cited by 5 | Viewed by 3131

Abstract

Acrylonitrile–Butadiene–Styrene (ABS) is a very significant and widely used amorphous thermoplastic that possesses high impact resistance, toughness, and heat resistance. Bending collapse is a predominant failure of polymeric structural members in the vehicle environment under angled and unsymmetrical collisions. Therefore, it becomes critical [...] Read more.

Acrylonitrile–Butadiene–Styrene (ABS) is a very significant and widely used amorphous thermoplastic that possesses high impact resistance, toughness, and heat resistance. Bending collapse is a predominant failure of polymeric structural members in the vehicle environment under angled and unsymmetrical collisions. Therefore, it becomes critical to investigate the flexural behavior of the ABS beam and find its energy absorption capabilities under a transverse loading scenario. Four-point bending tests were carried out at different strain rates and at two different span lengths to investigate the deformation behavior of ABS. This paper examines the influence of strain rate, friction coefficient, Generalized Incremental Stress-State MOdel (GISSMO) and Damage Initiation and Evolution (DIEM) damage models, yield surfaces, and the span length on the four-point flexural behavior of the ABS polymeric material. A Semi-Analytical material model (SAMP_1) in LSDYNA was utilized to numerically evaluate the behavior of ABS under four-point bending. From extensive investigative explorations, it was found that the flexural behavior of ABS is dependent upon the span length, loading strain rate, and friction coefficient between the specimen and the supports. The modeling of damage was successfully exemplified by using the inherent damage law of the SAMP-1 material model, GISSMO, and DIEM damage formulations. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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Review

Jump to: Research, Other

40 pages, 20071 KiB

Open AccessReview

Synthesis, Characterization, and Photocatalytic Performance of ZnO–Graphene Nanocomposites: A Review

by Elim Albiter, Aura S. Merlano, Elizabeth Rojas, José M. Barrera-Andrade, Ángel Salazar and Miguel A. Valenzuela

J. Compos. Sci. 2021, 5(1), 4; https://doi.org/10.3390/jcs5010004 - 25 Dec 2020

Cited by 20 | Viewed by 6084

Abstract

ZnO is an exciting material for photocatalysis applications due to its high activity, easy accessibility of raw materials, low production costs, and nontoxic. Several ZnO nano and microstructures can be obtained, such as nanoparticles, nanorods, micro flowers, microspheres, among others, depending on the [...] Read more.

ZnO is an exciting material for photocatalysis applications due to its high activity, easy accessibility of raw materials, low production costs, and nontoxic. Several ZnO nano and microstructures can be obtained, such as nanoparticles, nanorods, micro flowers, microspheres, among others, depending on the preparation method and conditions. ZnO is a wide bandgap semiconductor presenting massive recombination of the generated charge carriers, limiting its photocatalytic efficiency and stability. It is common to mix it with metal, metal oxide, sulfides, polymers, and nanocarbon-based materials to improve its photocatalytic behavior. Therefore, ZnO–nanocarbon composites formation has been a viable alternative that leads to new, more active, and stable photocatalytic systems. Mainly, graphene is a well-known two-dimensional material, which could be an excellent candidate to hybridize with ZnO due to its excellent physical and chemical properties (e.g., high specific surface area, optical transmittance, and thermal conductivity, among others). This review analyses ZnO–graphene nanocomposites’ recent advances, addressing the synthesis methods and the resulting structural, morphological, optical, and electronic properties. Moreover, we examine the ZnO–graphene composites’ role in the photocatalytic degradation of organic/inorganic pollutants. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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45 pages, 1816 KiB

Open AccessReview

Advanced Thermoplastic Composite Manufacturing by In-Situ Consolidation: A Review

by Isabel Martin, Diego Saenz del Castillo, Antonio Fernandez and Alfredo Güemes

J. Compos. Sci. 2020, 4(4), 149; https://doi.org/10.3390/jcs4040149 - 13 Oct 2020

Cited by 41 | Viewed by 5977

Abstract

This article provides an overview of the evolution of the in-situ consolidation (ISC) process over time. This evolution is intimately linked with the advancements in each of the steps of the ISC manufacturing process, is additive in nature, and is limited by the [...] Read more.

This article provides an overview of the evolution of the in-situ consolidation (ISC) process over time. This evolution is intimately linked with the advancements in each of the steps of the ISC manufacturing process, is additive in nature, and is limited by the orthotropic nature of composite materials and the physicochemical behavior of the thermoplastic matrix. This review covers four key topics: (a) Thermal models—simulation tools are critical to understand a process with such large spatial gradients and fast changes. Heating systems once marked a turning point in the development of industrial ISC systems. Today, lasers are the most recent trend, and there are three key issues being studied: The absorption of energy of light by the material, the laser profile, and the laser focusing. Several approaches have been proposed for the distributed temperature measurements, given the strong temperature gradients. (b) Adhesion—this refers to two subsequent mechanisms. In the first place, the process of intimate contact is one by which two surfaces of thermoplastic pre-impregnated composite materials are brought into contact under pressure and temperature. This enables closure of the existing gaps between the two microscopic irregular surfaces. This process is then followed by the healing or diffusion of polymer molecules across the interface. (c) Crystallinity—mostly influenced by the cooling rate, and strongly affects the mechanical properties. (d) Degradation—this refers to the potential irreversible changes in the polymer structure caused by the high temperatures required for the process. Degradation can be avoided through adequate control of the process parameters. The end goal of the ISC manufacturing process is to achieve a high product quality with a high deposition rate through an industrial process competitive with the current manufacturing process for thermoset composites. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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22 pages, 619 KiB

Open AccessEditor’s ChoiceReview

Mechanical Properties of Short Polymer Fiber-Reinforced Geopolymer Composites

by Kinga Korniejenko, Wei-Ting Lin and Hana Šimonová

J. Compos. Sci. 2020, 4(3), 128; https://doi.org/10.3390/jcs4030128 - 01 Sep 2020

Cited by 50 | Viewed by 3690

Abstract

The article describes the state of the art in reinforced geopolymers, taking into consideration various types of polymer fiber reinforcements, such as polypropylene, polyethylene, or polylactic acid. The description is focused on the usage of polymer short fibers and the mechanical properties of [...] Read more.

The article describes the state of the art in reinforced geopolymers, taking into consideration various types of polymer fiber reinforcements, such as polypropylene, polyethylene, or polylactic acid. The description is focused on the usage of polymer short fibers and the mechanical properties of the geopolymer composites. However, to show a wider research background, numerous references are discussed concerning the selected studies on reinforcing geopolymer composites with long fibers and fabrics. The research method applied in the article is the critical analysis of literature sources, including a comparison of new material with other materials used in similar applications. The results of the research are discussed in a comparative context and the properties of the composites are juxtaposed with the properties of the standard materials used in the construction industry. Potential applications in the construction industry are presented. Moreover, the contemporary research challenges for geopolymer materials reinforced with fibers are presented. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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26 pages, 11034 KiB

Open AccessReview

Factors that Affect Network Formation in Carbon Nanotube Composites and their Resultant Electrical Properties

by Morgan R. Watt and Rosario A. Gerhardt

J. Compos. Sci. 2020, 4(3), 100; https://doi.org/10.3390/jcs4030100 - 24 Jul 2020

Cited by 16 | Viewed by 2730

Abstract

This review paper explores the formation of carbon nanotube (CNT) polymer composites as a function of material and processing parameters. The effect of different polymer systems, increasing multiwall CNT content, modification of CNTs, processing conditions, and aspect ratio are discussed in detail for [...] Read more.

This review paper explores the formation of carbon nanotube (CNT) polymer composites as a function of material and processing parameters. The effect of different polymer systems, increasing multiwall CNT content, modification of CNTs, processing conditions, and aspect ratio are discussed in detail for multi-walled carbon nanotubes (MWCNT) composites along with some examples for SWCNT composites. All of these factors influence the microstructure and how the network of CNTs forms within it. Often, researchers choose to modify the CNTs to aid in their distribution; however, this may result in a reduction or increase in conductivity depending on many factors. The electrical properties are directly affected by changes in the CNT network and how the material has been processed. As soon as the network forms, percolation occurs and the conductivity increases. In order to understand how to control the properties of CNT composites, all material characteristics and processing conditions must be taken into account. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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1 pages, 179 KiB

Open AccessCorrection

Correction: The Mechanical and Material Designs of Composite Ju|’hoansi Arrowheads

by Courtney Archer, Iain Campbell, Fraser Cheyne, Amos Lim Jun Meng, Csongor Senanszky, Dimitrios Mamalis, Colin Robert and Parvez Alam

J. Compos. Sci. 2020, 4(4), 150; https://doi.org/10.3390/jcs4040150 - 13 Oct 2020

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Abstract

The authors would like to highlight the following correction to their published paper [...] Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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