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27 pages, 19016 KiB

Open AccessArticle

Assessing and Forecasting Fatigue Strength of Metals and Alloys under Cyclic Loads

by Andrey Kurkin, Alexander Khrobostov, Vyacheslav Andreev and Olga Andreeva

Materials 2024, 17(7), 1489; https://doi.org/10.3390/ma17071489 - 25 Mar 2024

Viewed by 599

Abstract

Within the scope of this research, patterns of changes in the fatigue life and limit of metals under cyclic stress were identified and the most informative parameters were determined as the basis for developing a method for the universal transformation of experimental data [...] Read more.

Within the scope of this research, patterns of changes in the fatigue life and limit of metals under cyclic stress were identified and the most informative parameters were determined as the basis for developing a method for the universal transformation of experimental data on the fatigue of metals and alloys for their subsequent generalization. Experimental data on metal fatigue, obtained by a large number of authors for a wide range of grades of steels and alloys, under the influence of various combinations of factors, were systematized. A generalized dependence of the recalculated parameters of fatigue life and limit was obtained, its characteristics were assessed, and a sensitivity analysis was performed, confirming the universal nature of the obtained dependence. A system of parameters has been proposed making it possible to consider and forecast high-cycle fatigue processes for a wide range of metals and alloys, under the conditions of various combinations of operating factors, from unified positions and a more general point of view. Full article

(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)

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12 pages, 6363 KiB

Open AccessArticle

Effects of Mode Mixity and Loading Rate on Fracture Behavior of Cracked Thin-Walled 304L Stainless Steel Sheets with Large Non-Linear Plastic Deformation

by Jamal Bidadi, Hamed Saeidi Googarchin, Alireza Akhavan-Safar and Lucas F. M. da Silva

Materials 2023, 16(24), 7690; https://doi.org/10.3390/ma16247690 - 18 Dec 2023

Cited by 1 | Viewed by 1042

Abstract

This study investigates the mixed-mode I/II fracture behavior of O-notched diagonally loaded square plate (DLSP) samples containing an edge crack within the O-notch. This investigation aims to explore the combined effects of loading rate and mode mixity on the fracture properties of steel [...] Read more.

This study investigates the mixed-mode I/II fracture behavior of O-notched diagonally loaded square plate (DLSP) samples containing an edge crack within the O-notch. This investigation aims to explore the combined effects of loading rate and mode mixity on the fracture properties of steel 304L, utilizing DLSP samples. The DLSP samples, made from strain-hardening steel 304L, were tested at three different loading rates: 1, 50, and 400 mm/min, covering five mode mixities from pure mode I to pure mode II. Additionally, tensile tests were performed on dumbbell-shaped specimens at the same loading rates to examine their influence on the material’s mechanical properties. The findings revealed that stress and strain diagrams derived from the dumbbell-shaped samples were largely independent of the tested loading rates (i.e., 1–400 mm/min). Furthermore, experimental results from DLSP samples showed no significant impact of the loading rates on the maximum load values, but did indicate an increase in the ultimate displacement. In contrast to the loading rate, mode mixity exhibited a notable effect on the fracture behavior of DLSP samples. Ultimately, it was observed that the loading rate had an insignificant effect on the fracture path or trajectory of the tested DLSP samples. Full article

(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)

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19 pages, 37740 KiB

Open AccessArticle

StressLife: A Short-Time Approach for the Determination of a Trend S-N Curve in and beyond the HCF Regime for the Steels 20MnMoNi5-5 and SAE 1045

by Fabian Weber, Janina Koziol and Peter Starke

Materials 2023, 16(11), 3914; https://doi.org/10.3390/ma16113914 - 23 May 2023

Cited by 3 | Viewed by 1598

Abstract

Within the scope of this research, a new short-time procedure designated as

S t r e s s L i f e_{H C F}

was developed. Through a combination of classic fatigue testing and non-destructive monitoring of the material response due to [...] Read more.

Within the scope of this research, a new short-time procedure designated as

S t r e s s L i f e_{H C F}

was developed. Through a combination of classic fatigue testing and non-destructive monitoring of the material response due to cyclic loading, a process-oriented fatigue life determination can be carried out. A total of two load increases and two constant amplitude tests are required for this procedure. By using data from non-destructive measurements, the parameters of the elastic approach according to Basquin and the plastic approach according to Manson–Coffin were determined and combined within the

S t r e s s L i f e_{H C F}

calculation. Furthermore, two additional variations of the

S t r e s s L i f e_{H C F}

method were developed in order to be able to accurately describe the S-N curve over a wider range. The main focus of this research was 20MnMoNi5-5 steel, which is a ferritic-bainitic steel (1.6310). This steel is widely used for spraylines in German nuclear power plants. In order to validate the findings, tests were also performed on an SAE 1045 steel (1.1191). Full article

(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)

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21 pages, 9283 KiB

Open AccessArticle

A Methodology to Predict the Fatigue Life under Multi-Axial Loading of Carbon Fiber-Reinforced Polymer Composites Considering Anisotropic Mechanical Behavior

by Joeun Choi, Hyungtak Lee, Hyungyil Lee and Naksoo Kim

Materials 2023, 16(5), 1952; https://doi.org/10.3390/ma16051952 - 27 Feb 2023

Cited by 4 | Viewed by 1632

Abstract

Carbon fiber-reinforced polymers (CFRP) have been actively employed as lightweight materials; yet, evaluating the material’s reliability under multi-axis stress states is still challenging owing to their anisotropic nature. This paper investigates the fatigue failures of short carbon-fiber reinforced polyamide-6 (PA6-CF) and polypropylene (PP-CF) [...] Read more.

Carbon fiber-reinforced polymers (CFRP) have been actively employed as lightweight materials; yet, evaluating the material’s reliability under multi-axis stress states is still challenging owing to their anisotropic nature. This paper investigates the fatigue failures of short carbon-fiber reinforced polyamide-6 (PA6-CF) and polypropylene (PP-CF) by analyzing the anisotropic behavior induced by the fiber orientation. The static and fatigue experiment and numerical analysis results of a one-way coupled injection molding structure have been obtained to develop the fatigue life prediction methodology. The maximum deviation between the experimental and calculated tensile results is 3.16%, indicating the accuracy of the numerical analysis model. The obtained data were utilized to develop the semi-empirical model based on the energy function, consisting of stress, strain, and triaxiality terms. Fiber breakage and matrix cracking occurred simultaneously during the fatigue fracture of PA6-CF. The PP-CF fiber was pulled out after matrix cracking due to weak interfacial bonding between the matrix and fiber. The reliability of the proposed model has been confirmed with high correlation coefficients of 98.1% and 97.9% for PA6-CF and PP-CF, respectively. In addition, the prediction percentage errors of the verification set for each material were 38.6% and 14.5%, respectively. Although the results of the verification specimen collected directly from the cross-member were included, the percentage error of PA6-CF was still relatively low at 38.6%. In conclusion, the developed model can predict the fatigue life of CFRPs, considering anisotropy and multi-axial stress states. Full article

(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)

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22 pages, 9479 KiB

Open AccessArticle

Determination of Dimple Core Design Configurations for Sandwich Panel Enhancement Using Fuzzy-Hybrid Decision Making Analysis

by Mohd Khairul Faidzi, Shahrum Abdullah, Salvinder Singh Karam Singh, Mohamad Faizal Abdullah and Abdul Hadi Azman

Materials 2023, 16(3), 935; https://doi.org/10.3390/ma16030935 - 18 Jan 2023

Viewed by 1861

Abstract

The purpose of this paper is to determine the best dimple core design for metal sandwich panels by investigating the various critical criteria and core design parameters using the fuzzy-hybrid multi-criteria decision-making tool. The structural integrity of a sandwich panel depends on the [...] Read more.

The purpose of this paper is to determine the best dimple core design for metal sandwich panels by investigating the various critical criteria and core design parameters using the fuzzy-hybrid multi-criteria decision-making tool. The structural integrity of a sandwich panel depends on the core design and significantly affects the bonding strength. The continuous design and testing of a sandwich panel is a very lengthy process that increases the design time. The simulation analysis output was segregated into nine critical failure criteria. All the critical criteria weightages were evaluated using the Fuzzy-Analytical Hierarchical Process, while the Fuzzy—Technique for Order Preference by Similarity to Ideal Solution was used to evaluate the Closeness Coefficient value to determine the best core design configuration. The results indicate that the core configuration with a diameter of 6.0 mm and a depth of 3.0 mm obtained the highest closeness coefficient values, 0.9937 and 0.9294, under cyclic loading conditions of 50% and 70%. It was shown that using average sizes in the dimple configuration tends to provide better delamination resistance and structural integrity. This study contributes to the selection of the optimum core design configuration based on the various design criteria and using non-complex and competent analysis. Full article

(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)

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21 pages, 7191 KiB

Open AccessArticle

Fatigue Life Assessment of API Steel Grade X65 Pipeline Using a Modified Basquin Parameter of the Magnetic Flux Leakage Signal

by Syed Muhamad Firdaus, Azli Arifin, Shahrum Abdullah, Salvinder Singh Karam Singh and Noorsuhada Md Nor

Materials 2023, 16(2), 464; https://doi.org/10.3390/ma16020464 - 4 Jan 2023

Cited by 3 | Viewed by 2015

Abstract

This paper presents a modified fatigue life model of the Basquin equation using the stress parameter of the magnetic flux leakage signal. Most pipeline steels experience cyclic loading during service and the influence of the load history makes assessing fatigue behaviour more difficult. [...] Read more.

This paper presents a modified fatigue life model of the Basquin equation using the stress parameter of the magnetic flux leakage signal. Most pipeline steels experience cyclic loading during service and the influence of the load history makes assessing fatigue behaviour more difficult. The magnetic flux leakage signal’s response to a uniaxial cyclic test of API X65 steel was measured with eight levels of ultimate tensile stress loads. The influence of dH(y)/dx on fatigue failure was the main concern in this study, the aim being to represent localised stress parameters in the modified Basquin equation. Both fatigue lives, experimental and predicted from the modified Basquin equation, were validated through reliability analysis, producing a 60% value when approaching 1.8 × 10⁵ cycles. The fatigue data from the experiment produced a higher mean-cycle-to-failure value than the prediction data, with slightly different values of 3.37 × 10⁵ and 3.28 × 10⁵. Additionally, the modified Basquin equation’s predicted and the experimental fatigue lives were found to have a high R² correlation value of 0.9022. The Pearson correlation also showed a good relationship between the fatigue lives, with an r value of 0.9801. Finally, the modified Basquin equation based on dH(y)/dx signals provided an accurate and alternative method for durability assessment. Full article

(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)

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22 pages, 11399 KiB

Open AccessArticle

Fatigue Reliability Characterisation of Effective Strain Damage Model Using Extreme Value Distribution for Road Load Conditions

by Lennie Abdullah, Salvinder Singh Karam Singh, Shahrum Abdullah, Ahmad Kamal Ariffin and Syifa Syuhaidah Meor Zainal

Materials 2023, 16(1), 456; https://doi.org/10.3390/ma16010456 - 3 Jan 2023

Cited by 1 | Viewed by 2205

Abstract

The aim of this paper is to characterise the fatigue reliability for various random strain loads under extreme value distribution while considering the cycle sequence effect condition in fatigue life prediction. The established strain–life models, i.e., Morrow and Smith–Watson–Topper, considered a mean stress [...] Read more.

The aim of this paper is to characterise the fatigue reliability for various random strain loads under extreme value distribution while considering the cycle sequence effect condition in fatigue life prediction. The established strain–life models, i.e., Morrow and Smith–Watson–Topper, considered a mean stress effect and strain amplitude; nevertheless, it excluded the load sequence effect, which involves the fatigue crack closure that is subjected to overload or underload. A FESEM-EDX analysis is conducted to characterise the failure features that occurred on the leaf spring. A finite element is simulated to determine the critical region in order to obtain the strain load behaviour. In addition, the strain signal is captured experimentally at 500 Hz for 100 s under operating conditions for three different road loads based on the critical location obtained from the finite element analysis. The fatigue life correlation shows that the Pearson correlation coefficients are greater than 0.9, which indicates the effective strain damage model is linearly correlated with the strain–life models. The fatigue life data are modelled using extreme value distribution by considering the random strain loads as extreme data. The reliability rate for the fatigue life is reported to be more than 0.59 within the hazard rate range of 9.6 × 10⁻⁸ to 1.2 × 10⁻⁷ based on the mean cycle to the failure point. Hence, the effective strain damage model is proposed for a fatigue reliability assessment under extreme conditions with higher reliability and provides fatigue life prediction when subjected to cycle sequence effects. Full article

(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)

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16 pages, 5479 KiB

Open AccessArticle

Mixed Mode Fracture Investigation of Rock Specimens Containing Sharp V-Notches

by Ali Arabnia, Javad Akbardoost, Sergio Cicero and Ali Reza Torabi

Materials 2022, 15(24), 8779; https://doi.org/10.3390/ma15248779 - 8 Dec 2022

Cited by 3 | Viewed by 1034

Abstract

This work aims to assess both experimentally and analytically the fracture behavior of rock specimens containing sharp V-notches (SV-notches) subjected to mixed mode I/II loading. To this end, firstly, several mixed mode fracture tests were conducted on Brazilian disk specimens weakened by an [...] Read more.

This work aims to assess both experimentally and analytically the fracture behavior of rock specimens containing sharp V-notches (SV-notches) subjected to mixed mode I/II loading. To this end, firstly, several mixed mode fracture tests were conducted on Brazilian disk specimens weakened by an SV-notch (SVNBD sample), performed in their corresponding center and with various notch opening angles. Secondly, the fracture resistance of the tested samples was predicted using a criterion named MTS-FEM. This approach is based on the maximum tangential stress (MTS) criterion, in which the tangential stress is determined from the finite element method (FEM). Additionally, in the present research, the required critical distance is calculated directly from finite element analyses performed on cracked samples. Comparing the experimental results and the analytical predictions, it is shown that the fracture curves obtained from the MTS-FEM criterion are in agreement with the experimental results. These results are achieved without the need for the calculation of stress series expansion coefficients, as an additional advantage of the proposed approach. Full article

(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)

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Review

Jump to: Research

36 pages, 5506 KiB

Open AccessReview

A Literature Review of Incorporating Crack Tip Plasticity into Fatigue Crack Growth Models

by Antonio Garcia-Gonzalez, Jose A. Aguilera, Pablo M. Cerezo, Cristina Castro-Egler and Pablo Lopez-Crespo

Materials 2023, 16(24), 7603; https://doi.org/10.3390/ma16247603 - 11 Dec 2023

Viewed by 1551

Abstract

This paper presents an extensive literature review focusing on the utilisation of crack tip plasticity as a crucial parameter in determining and enhancing crack growth models. The review encompasses a comprehensive analysis of various methodologies, predominantly emphasising numerical simulations of crack growth models [...] Read more.

This paper presents an extensive literature review focusing on the utilisation of crack tip plasticity as a crucial parameter in determining and enhancing crack growth models. The review encompasses a comprehensive analysis of various methodologies, predominantly emphasising numerical simulations of crack growth models while also considering analytical approaches. Although experimental investigations are not the focus of this review, their relevance and interplay with numerical and analytical methods are acknowledged. The paper critically examines these methodologies, providing insights into their advantages and limitations. Ultimately, this review aims to offer a holistic understanding of the role of crack tip plasticity in the development of effective crack growth models, highlighting the synergies and gaps between theoretical, experimental, and simulation-based approaches. Full article

(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)

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25 pages, 8996 KiB

Open AccessReview

A Robust Adaptive Mesh Generation Algorithm: A Solution for Simulating 2D Crack Growth Problems

by Abdulnaser M. Alshoaibi and Yahya Ali Fageehi

Materials 2023, 16(19), 6481; https://doi.org/10.3390/ma16196481 - 29 Sep 2023

Cited by 1 | Viewed by 1110

Abstract

This paper introduces a robust algorithm that efficiently generates high-quality unstructured triangular meshes to model complex two-dimensional crack growth problems within the framework of linear elastic fracture mechanics (LEFM). The proposed Visual Fortran code aims to address key challenges in mesh generation including [...] Read more.

This paper introduces a robust algorithm that efficiently generates high-quality unstructured triangular meshes to model complex two-dimensional crack growth problems within the framework of linear elastic fracture mechanics (LEFM). The proposed Visual Fortran code aims to address key challenges in mesh generation including geometric complexity, required simulation accuracy, and computational resource constraints. The algorithm incorporates adaptive refinement and updates to the mesh structure near the crack tip, resulting in the formation of rosette elements that provide accurate approximations of stress intensity factors (SIFs). By utilizing the maximum circumferential stress theory, the algorithm predicts the new crack path based on these SIFs. Throughout the simulation of crack propagation, a node splitting approach was employed to represent the progression of the crack, while the crack growth path is determined by successive linear extensions for each crack growth increment. To compute stress intensity factors (SIFs) for each increment of crack extension, a displacement extrapolation method was used. The experimental and numerical results demonstrated the algorithm’s effectiveness in accurately predicting crack growth and facilitating reliable stress analysis for complex crack growth problems in two dimensions. The obtained results for the SIF were found to be consistent with other analytical solutions for standard geometries. Full article

(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)

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28 pages, 9126 KiB

Open AccessReview

A Review on Nonlocal Theories in Fatigue Assessment of Solids

by Saeed H. Moghtaderi, Alias Jedi and Ahmad Kamal Ariffin

Materials 2023, 16(2), 831; https://doi.org/10.3390/ma16020831 - 15 Jan 2023

Cited by 3 | Viewed by 1600

Abstract

A review of nonlocal theories utilized in the fatigue and fracture modeling of solid structures is addressed in this paper. Numerous papers have been studied for this purpose, and various nonlocal theories such as the nonlocal continuum damage model, stress field intensity model, [...] Read more.

A review of nonlocal theories utilized in the fatigue and fracture modeling of solid structures is addressed in this paper. Numerous papers have been studied for this purpose, and various nonlocal theories such as the nonlocal continuum damage model, stress field intensity model, peridynamics model, elastic-plastic models, energy-based model, nonlocal multiscale model, microstructural sensitive model, nonlocal lattice particle model, nonlocal high cycle fatigue model, low cycle fatigue model, nonlocal and gradient fracture criteria, nonlocal coupled damage plasticity model and nonlocal fracture criterion have been reviewed and summarized in the case of fatigue and fracture of solid structures and materials. Full article

(This article belongs to the Special Issue Fatigue Damage and Fracture Mechanics of Materials)

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