Pub Date : 2025-03-09DOI: 10.1016/j.ijfatigue.2025.108927
Yaping Liu , Yu Qi , Haipeng Cao , Yongbo Shao , Xudong Gao , Wentao He
This paper aims to investigate the fatigue behavior and damage mechanism of AH36 steel under low-cycle fatigue (LCF) loading by a combined experimental and numerical approach. Systemic monotonic tensile and cyclic loading tests with different loading protocols are conducted to calibrate and determine the elastic and plastic model parameters, and to explore cyclic stress–strain response as well as LCF damage behavior. A continuum damage coupled unified elastoplastic model based on the continuum damage mechanics is proposed to describe the hysteresis behavior and fatigue characteristic of AH36 steel; meanwhile, a procedure is developed by the VUMAT subroutine in ABAQUS/Explicit to numerically evaluate the fatigue damage evolution and lifetime prediction throughout the whole fatigue process. Fatigue damage accumulation and stress redistribution within the structure are conducted to clarify damage initiation and evolution process until structural failure. Reasonably good agreement is achieved when comparing the cyclic stress–strain response and stress peak between experimental measurements and numerical simulation, and lifetime prediction indicates better accuracy with an average error of less than 10%.
{"title":"Low-cycle fatigue behavior and damage mechanism of AH36 steel based on a continuum damage coupled unified elastoplastic model","authors":"Yaping Liu , Yu Qi , Haipeng Cao , Yongbo Shao , Xudong Gao , Wentao He","doi":"10.1016/j.ijfatigue.2025.108927","DOIUrl":"10.1016/j.ijfatigue.2025.108927","url":null,"abstract":"<div><div>This paper aims to investigate the fatigue behavior and damage mechanism of AH36 steel under low-cycle fatigue (LCF) loading by a combined experimental and numerical approach. Systemic monotonic tensile and cyclic loading tests with different loading protocols are conducted to calibrate and determine the elastic and plastic model parameters, and to explore cyclic stress–strain response as well as LCF damage behavior. A continuum damage coupled unified elastoplastic model based on the continuum damage mechanics is proposed to describe the hysteresis behavior and fatigue characteristic of AH36 steel; meanwhile, a procedure is developed by the VUMAT subroutine in ABAQUS/Explicit to numerically evaluate the fatigue damage evolution and lifetime prediction throughout the whole fatigue process. Fatigue damage accumulation and stress redistribution within the structure are conducted to clarify damage initiation and evolution process until structural failure. Reasonably good agreement is achieved when comparing the cyclic stress–strain response and stress peak between experimental measurements and numerical simulation, and lifetime prediction indicates better accuracy with an average error of less than 10%.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108927"},"PeriodicalIF":5.7,"publicationDate":"2025-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study quantifies the interaction between volumetric defect location and size on the very high cycle fatigue (VHCF) of laser beam powder bed fused (LB-PBF) AlSi10Mg. Crystal plasticity finite element method (CPFEM) simulations were used to investigate the effects of defect location and size on the driving force for crack initiation. The CPFEM model was calibrated against uniaxial and cyclic experimental data of LB-PBF AlSi10Mg. Defect characteristics were informed by experimental data from the specimens produced in various geometries to create realistic representative volume elements (RVEs) with equivalent volume fractions of defects. By embedding defects of varying sizes and locations within the RVEs, fatigue indicator parameters (FIPs) were calculated to analyze the impact of defects’ characteristics on fatigue performance. Different combinations of defect volume and locations were generated for various microstructure instantiations, providing insight into extreme value fatigue responses. Larger defect volumes located on free surfaces consistently generated the highest FIPs, suggesting defect size and boundary proximity intensify stress concentration effects. RVEs with multiple smaller defects produced lower FIPs than those with single large critical defects. These findings underscore the critical role of defect characteristics on fatigue life, providing a foundation for future predictive modeling in fatigue-sensitive AM applications.
{"title":"Simulated effect of defect volume and location on very high cycle fatigue of laser beam powder bed fused AlSi10Mg","authors":"Kamin Tahmasbi , Mohammadreza Yaghoobi , Shuai Shao , Nima Shamsaei , Meysam Haghshenas","doi":"10.1016/j.ijfatigue.2025.108926","DOIUrl":"10.1016/j.ijfatigue.2025.108926","url":null,"abstract":"<div><div>This study quantifies the interaction between volumetric defect location and size on the very high cycle fatigue (VHCF) of laser beam powder bed fused (LB-PBF) AlSi10Mg. Crystal plasticity finite element method (CPFEM) simulations were used to investigate the effects of defect location and size on the driving force for crack initiation. The CPFEM model was calibrated against uniaxial and cyclic experimental data of LB-PBF AlSi10Mg. Defect characteristics were informed by experimental data from the specimens produced in various geometries to create realistic representative volume elements (RVEs) with equivalent volume fractions of defects. By embedding defects of varying sizes and locations within the RVEs, fatigue indicator parameters (FIPs) were calculated to analyze the impact of defects’ characteristics on fatigue performance. Different combinations of defect volume and locations were generated for various microstructure instantiations, providing insight into extreme value fatigue responses. Larger defect volumes located on free surfaces consistently generated the highest FIPs, suggesting defect size and boundary proximity intensify stress concentration effects. RVEs with multiple smaller defects produced lower FIPs than those with single large critical defects. These findings underscore the critical role of defect characteristics on fatigue life, providing a foundation for future predictive modeling in fatigue-sensitive AM applications.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108926"},"PeriodicalIF":5.7,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-07DOI: 10.1016/j.ijfatigue.2025.108925
Haizhou Li , Rui Lu , Rui Su , Yan Liu , Zhenlin Zhang , Yong Chen , Yongjie Liu , Qingyuan Wang , Hui Chen
Fatigue cracks often initiate from the small defects, leading to the degradation of fatigue property, which has been a bottleneck problem that restricts the application of additive titanium alloys. To improve this problem, we propose a new low stress cyclic strengthening method (LSCSM) to precisely induce the precipitation of new granular α′ around the internal small pore, and ultimately achieve a significant enhancement in the high cycle fatigue life (HCFL) of additive Ti-6Al-4V titanium alloys. By combining cross-scale microstructure characterization and molecular dynamics simulation, we reveal the strengthening mechanism of LSCSM based on the micro-plastic deformation evolution during phase transformation. We find that a new granular α′ (three different crystal structures with crystal band axes of , and , respectively) can precipitate during LSCSM, which nucleates with dislocations as nucleation points and grows by dislocations annihilation. During this process, the number of dislocations and stress/strain field within the granular α′ are gradually reduced, which can significantly enhance HCFL (52 times) due to the recovery from fatigue damage. This work has important engineering application value in strengthening of key components of aircraft engines.
{"title":"Strengthening mechanism of additively manufactured Ti-6Al-4V titanium alloy by deformable-restoring granular α′","authors":"Haizhou Li , Rui Lu , Rui Su , Yan Liu , Zhenlin Zhang , Yong Chen , Yongjie Liu , Qingyuan Wang , Hui Chen","doi":"10.1016/j.ijfatigue.2025.108925","DOIUrl":"10.1016/j.ijfatigue.2025.108925","url":null,"abstract":"<div><div>Fatigue cracks often initiate from the small defects, leading to the degradation of fatigue property, which has been a bottleneck problem that restricts the application of additive titanium alloys. To improve this problem, we propose a new low stress cyclic strengthening method (LSCSM) to precisely induce the precipitation of new granular <em>α</em>′ around the internal small pore, and ultimately achieve a significant enhancement in the high cycle fatigue life (HCFL) of additive Ti-6Al-4V titanium alloys. By combining cross-scale microstructure characterization and molecular dynamics simulation, we reveal the strengthening mechanism of LSCSM based on the micro-plastic deformation evolution during phase transformation. We find that a new granular <em>α</em>′ (three different crystal structures with crystal band axes of <span><math><mrow><mo>[</mo><mover><mrow><mtext>2</mtext></mrow><mrow><mo>¯</mo></mrow></mover><mtext>4</mtext><mover><mrow><mtext>2</mtext></mrow><mrow><mo>¯</mo></mrow></mover><mtext>3</mtext><mo>]</mo></mrow></math></span>, <span><math><mrow><mo>[</mo><mtext>01</mtext><mover><mrow><mtext>1</mtext></mrow><mrow><mo>¯</mo></mrow></mover><mtext>1</mtext><mo>]</mo></mrow></math></span> and <span><math><mrow><mo>[</mo><mtext>01</mtext><mover><mrow><mtext>1</mtext></mrow><mrow><mo>¯</mo></mrow></mover><mtext>0</mtext><mo>]</mo></mrow></math></span>, respectively) can precipitate during LSCSM, which nucleates with dislocations as nucleation points and grows by dislocations annihilation. During this process, the number of dislocations and stress/strain field within the granular <em>α</em>′ are gradually reduced, which can significantly enhance HCFL (52 times) due to the recovery from fatigue damage. This work has important engineering application value in strengthening of key components of aircraft engines.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108925"},"PeriodicalIF":5.7,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-07DOI: 10.1016/j.ijfatigue.2025.108924
R. Kumar , J. Bhagyaraj , E. Hari Krishna , S. Mukherjee , K. Prasad , S. Mandal
In this work, thermomechanical fatigue (TMF) life of Timetal 834 alloy is studied under clockwise diamond (CD) and counterclockwise diamond (CCD) conditions in the intermediate temperature range (i.e., 573 K ↔ 723 K). TMF tests were performed at strain amplitude of Δ/2 = ±0.6 % and ± 1.0 % and post-failure, microstructure of each specimen was characterized by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) techniques. TMF results show that life is shorter under CD condition than CCD one at a given strain amplitude due to accumulation of greater tensile damage during each cycle. The local average misorientation analyses confirm that strain localization is greater under CD condition than CCD one at a given strain amplitude. In this study, crack initiation and the associated failure mechanism are also investigated. EBSD analyses show band-like structure inside the primary alpha (αp) grains where strain localization is substantially greater in both TMF conditions. TEM results corroborate with the EBSD findings and show dense dislocation density at the concavities around αp grain boundaries. The fractography studies show faceted αp grains near the crack initiation sites. EBSD analyses reveal that facets are interrelated with strain localization in αp grains, oriented along basal or prismatic with high Schmid factor.
{"title":"Cyclic deformation behavior and micro-mechanism of crack initiation during thermomechanical fatigue in an intermediate temperature range (573 K ↔ 723 K) in Timetal 834 alloy","authors":"R. Kumar , J. Bhagyaraj , E. Hari Krishna , S. Mukherjee , K. Prasad , S. Mandal","doi":"10.1016/j.ijfatigue.2025.108924","DOIUrl":"10.1016/j.ijfatigue.2025.108924","url":null,"abstract":"<div><div>In this work, thermomechanical fatigue (TMF) life of Timetal 834 alloy is studied under clockwise diamond (CD) and counterclockwise diamond (CCD) conditions in the intermediate temperature range (i.e., 573 K ↔ 723 K). TMF tests were performed at strain amplitude of Δ<span><math><mrow><msub><mi>ε</mi><mi>m</mi></msub></mrow></math></span>/2 = ±0.6 % and ± 1.0 % and post-failure, microstructure of each specimen was characterized by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) techniques. TMF results show that life is shorter under CD condition than CCD one at a given strain amplitude due to accumulation of greater tensile damage during each cycle. The local average misorientation analyses confirm that strain localization is greater under CD condition than CCD one at a given strain amplitude. In this study, crack initiation and the associated failure mechanism are also investigated. EBSD analyses show band-like structure inside the primary alpha (α<sub>p</sub>) grains where strain localization is substantially greater in both TMF conditions. TEM results corroborate with the EBSD findings and show dense dislocation density at the concavities around α<sub>p</sub> grain boundaries. The fractography studies show faceted α<sub>p</sub> grains near the crack initiation sites. EBSD analyses reveal that facets are interrelated with strain localization in α<sub>p</sub> grains, oriented along basal or prismatic with high Schmid factor.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108924"},"PeriodicalIF":5.7,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-06DOI: 10.1016/j.ijfatigue.2025.108912
Xingkeng Shen , Hongmin Zhou , Yishang Zhang , Wei Liu , Mao Xu , Qiu Zhang , Ying Dai , Xinmin Chen
The fuel piping system is vital for fuel transportation and the corresponding reliability is the necessary prerequisite for the normal operation of aero engines. Given the broad frequency range of external excitations, structural resonance of the fuel piping system is unavoidable, often leading to structural fatigue failure. This paper aims to elucidate the mechanisms of fatigue failure and establish a framework for probabilistic fatigue life assessment of the fuel piping system under prolonged resonance excitation. Firstly, sweep frequency and resonance fatigue tests of fuel piping system are conducted to determine the resonance frequencies, resonance strain responses and corresponding fatigue lives. The accuracy and effectiveness of the finite element model, as well as previously established fatigue life models for the components of the piping system, are then validated through deterministic modal and implicit dynamic analysis. Subsequently, a distributed collaborative (DC) probabilistic analysis method, based on the cross-validation (CV)-Voronoi sequential sampling approach for Kriging surrogate model (DC-CV-Voronoi-KSM), is proposed for reliability analysis of resonance fatigue. The novelty of this method lies in the use of the CV-Voronoi method as a sequential sampling approach for constructing a global Kriging surrogate model, with the DC strategy employed to reduce the complexity of Kriging model. Finally, the DC-CV-Voronoi-KSM method is adopted to conduct reliability analysis on the resonance fatigue of the fuel piping system, yielding the distribution of resonance responses and the load cycle-failure probability curve, which provides significant guidance for the application of fuel piping systems on aero engines.
{"title":"Reliability analysis on resonance fatigue life of fuel piping system","authors":"Xingkeng Shen , Hongmin Zhou , Yishang Zhang , Wei Liu , Mao Xu , Qiu Zhang , Ying Dai , Xinmin Chen","doi":"10.1016/j.ijfatigue.2025.108912","DOIUrl":"10.1016/j.ijfatigue.2025.108912","url":null,"abstract":"<div><div>The fuel piping system is vital for fuel transportation and the corresponding reliability is the necessary prerequisite for the normal operation of aero engines. Given the broad frequency range of external excitations, structural resonance of the fuel piping system is unavoidable, often leading to structural fatigue failure. This paper aims to elucidate the mechanisms of fatigue failure and establish a framework for probabilistic fatigue life assessment of the fuel piping system under prolonged resonance excitation. Firstly, sweep frequency and resonance fatigue tests of fuel piping system are conducted to determine the resonance frequencies, resonance strain responses and corresponding fatigue lives. The accuracy and effectiveness of the finite element model, as well as previously established fatigue life models for the components of the piping system, are then validated through deterministic modal and implicit dynamic analysis. Subsequently, a distributed collaborative (DC) probabilistic analysis method, based on the cross-validation (CV)-Voronoi sequential sampling approach for Kriging surrogate model (DC-CV-Voronoi-KSM), is proposed for reliability analysis of resonance fatigue. The novelty of this method lies in the use of the CV-Voronoi method as a sequential sampling approach for constructing a global Kriging surrogate model, with the DC strategy employed to reduce the complexity of Kriging model. Finally, the DC-CV-Voronoi-KSM method is adopted to conduct reliability analysis on the resonance fatigue of the fuel piping system, yielding the distribution of resonance responses and the load cycle-failure probability curve, which provides significant guidance for the application of fuel piping systems on aero engines.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108912"},"PeriodicalIF":5.7,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-06DOI: 10.1016/j.ijfatigue.2025.108916
Guang-jun Zeng , You-jie Guo , Chen-chen Xiong , Hao-ran Li , Wei Zhou , Hui Xiang , Peng-cheng Ma , Yong-lai Chen , Jin-feng Li , Dan-yang Liu
The fatigue crack propagation (FCP) resistance of Al-Cu-Li alloys was improved via regulating grain structure and precipitation behavior, and their effect on the FCP rate was further elucidated. It was revealed that modifying the solution heating rate significantly affected the grain structure and FCP behavior. Specifically, the decreased solution heating rate resulted in an alternative distribution of recrystallized grains and sub-grain bands, with a larger recrystallized-grain size and increased sub-grain band density. This microstructural evolution altered the reversible plastic zone (Rp) scale at the crack tip, where the Rp/D ratio (D: recrystallized-grain size) in samples with 2 °C/min solution heating rate (2HR) ranged from 0.31 to 1.22, leading to transgranular crack propagation and decreased FCP rates. Furthermore, the sub-grain zones in 2HR sample exhibited low tilt and twist angle differences and featured shearable T1 precipitates, promoting crack deviation and bifurcation. In contrast, the specimens subjected to direct solution treatment (DST) showed a by-passing mechanism during T1 precipitates-dislocation interaction. The shearable T1 precipitates contributed to strain energy release, while the by-passed T1 precipitates facilitated intergranular crack propagation. Thus, the FCP resistance of 2HR sample was significantly enhanced compared to DST sample. These findings provided a novel approach to improving the FCP resistance of Al-Cu-Li alloy through controlled microstructural design.
{"title":"Enhanced fatigue crack propagation resistance of Al-Cu-Li alloys via regulating grain structure and precipitation behavior","authors":"Guang-jun Zeng , You-jie Guo , Chen-chen Xiong , Hao-ran Li , Wei Zhou , Hui Xiang , Peng-cheng Ma , Yong-lai Chen , Jin-feng Li , Dan-yang Liu","doi":"10.1016/j.ijfatigue.2025.108916","DOIUrl":"10.1016/j.ijfatigue.2025.108916","url":null,"abstract":"<div><div>The fatigue crack propagation (FCP) resistance of Al-Cu-Li alloys was improved via regulating grain structure and precipitation behavior, and their effect on the FCP rate was further elucidated. It was revealed that modifying the solution heating rate significantly affected the grain structure and FCP behavior. Specifically, the decreased solution heating rate resulted in an alternative distribution of recrystallized grains and sub-grain bands, with a larger recrystallized-grain size and increased sub-grain band density. This microstructural evolution altered the reversible plastic zone (<em>Rp</em>) scale at the crack tip, where the <em>R<sub>p</sub>/D</em> ratio (D: recrystallized-grain size) in samples with 2 °C/min solution heating rate (2HR) ranged from 0.31 to 1.22, leading to transgranular crack propagation and decreased FCP rates. Furthermore, the sub-grain zones in 2HR sample exhibited low tilt and twist angle differences and featured shearable T<sub>1</sub> precipitates, promoting crack deviation and bifurcation. In contrast, the specimens subjected to direct solution treatment (DST) showed a by-passing mechanism during T<sub>1</sub> precipitates-dislocation interaction. The shearable T<sub>1</sub> precipitates contributed to strain energy release, while the by-passed T<sub>1</sub> precipitates facilitated intergranular crack propagation. Thus, the FCP resistance of 2HR sample was significantly enhanced compared to DST sample. These findings provided a novel approach to improving the FCP resistance of Al-Cu-Li alloy through controlled microstructural design.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108916"},"PeriodicalIF":5.7,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143583090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-05DOI: 10.1016/j.ijfatigue.2025.108911
Jiaxuan Zhang , Wen Cai , Bin Li , Liyuan Li , Wenchao Niu
Macro Fiber Composite (MFC) demonstrates promising application in morphing structure actuation and structural vibration active control. MFC patches are subject to mechanical loads in conjunction with the structure, which may result in actuation performance degradation. The actuation may not proceed as intended after the degradation. However, the actuation degradation of MFC under mechanical loading has been rarely addressed. In this study, the actuation degradation of MFC under mechanical loads respectively at room and higher temperatures is first investigated by experiments. The experimental results indicate that the mechanical-induced MFC actuation degradation exhibits a nonlinear trend, and compressive loads show a trivial impact on the actuation degradation. Mechanical-induced actuation degradation becomes more significant with the increase of the tensile load and temperature. Further, a finite element model based on a damage evolution model is proposed for the sake of time and economic cost. The predictions align well with the experimental data. The experimental evidence and theoretical predictions show that the mechanical-induced actuation degradation arises from the MFC stiffness degradation and irreversible degradation of piezoelectric properties. The finite element model further verifies that the microcracks accumulation before the creation of the visible cracks contributes to the great initial degradation.
{"title":"Experimental and theoretical investigations of macro fiber composite actuation degradation induced by the mechanical load","authors":"Jiaxuan Zhang , Wen Cai , Bin Li , Liyuan Li , Wenchao Niu","doi":"10.1016/j.ijfatigue.2025.108911","DOIUrl":"10.1016/j.ijfatigue.2025.108911","url":null,"abstract":"<div><div>Macro Fiber Composite (MFC) demonstrates promising application in morphing structure actuation and structural vibration active control. MFC patches are subject to mechanical loads in conjunction with the structure, which may result in actuation performance degradation. The actuation may not proceed as intended after the degradation. However, the actuation degradation of MFC under mechanical loading has been rarely addressed. In this study, the actuation degradation of MFC under mechanical loads respectively at room and higher temperatures is first investigated by experiments. The experimental results indicate that the mechanical-induced MFC actuation degradation exhibits a nonlinear trend, and compressive loads show a trivial impact on the actuation degradation. Mechanical-induced actuation degradation becomes more significant with the increase of the tensile load and temperature. Further, a finite element model based on a damage evolution model is proposed for the sake of time and economic cost. The predictions align well with the experimental data. The experimental evidence and theoretical predictions show that the mechanical-induced actuation degradation arises from the MFC stiffness degradation and irreversible degradation of piezoelectric properties. The finite element model further verifies that the microcracks accumulation before the creation of the visible cracks contributes to the great initial degradation.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108911"},"PeriodicalIF":5.7,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143578453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-05DOI: 10.1016/j.ijfatigue.2025.108913
Mritunjay M. Hiremath , Nikhar Doshi , Timo Bernthaler , Pascal Anger , Sushil K. Mishra , Anirban Guha , Asim Tewari
Tension-compression cyclic loading poses significant challenges due to its severe impact on the stiffness degradation of composites, making accurate predictions of microstructural damage essential for structural reliability. In this study, microstructural damage in woven composites is analysed using X-ray microscopy under equal and critical stress ratio conditions of tension–compression cyclic loading. Quantified damage data are used to train machine learning models, including support vector regression (SVR), random forest (RF) and neural network (NN). Experimental results revealed that under both stress ratios, perpendicular cracks initiated first, followed by cracks at the weft/warp interface. The degradation in the stiffness was approximately 22.46 % under the equal stress ratio condition and 17.62 % under critical stress ratio condition after 100,000 cycles. Machine learning models demonstrated robust performance, with SVR (average error rate = 0.15 %) and RF (average error rate = 0.13 %) closely aligning with experimental data when trained and tested on their respective stress ratios. Notably, flipped dataset analysis revealed that RF (average error rate = 1.02 %) and NN (average error rate = 1.05 %) models trained on equal stress ratio data effectively predicted critical stress ratio behaviour, showcasing their adaptability. These findings highlight the potential of machine learning-driven approaches for predictive modelling, enabling more efficient material design and optimization under cyclic loading conditions.
{"title":"3D damage evolution and microstructural-based machine learning model for stiffness prediction in woven composite under cyclic loads","authors":"Mritunjay M. Hiremath , Nikhar Doshi , Timo Bernthaler , Pascal Anger , Sushil K. Mishra , Anirban Guha , Asim Tewari","doi":"10.1016/j.ijfatigue.2025.108913","DOIUrl":"10.1016/j.ijfatigue.2025.108913","url":null,"abstract":"<div><div>Tension-compression cyclic loading poses significant challenges due to its severe impact on the stiffness degradation of composites, making accurate predictions of microstructural damage essential for structural reliability. In this study, microstructural damage in woven composites is analysed using X-ray microscopy under equal and critical stress ratio conditions of tension–compression cyclic loading. Quantified damage data are used to train machine learning models, including support vector regression (SVR), random forest (RF) and neural network (NN). Experimental results revealed that under both stress ratios, perpendicular cracks initiated first, followed by cracks at the weft/warp interface. The degradation in the stiffness was approximately 22.46 % under the equal stress ratio condition and 17.62 % under critical stress ratio condition after 100,000 cycles<em>.</em> Machine learning models demonstrated robust performance, with SVR (average error rate = 0.15 %) and RF (average error rate = 0.13 %) closely aligning with experimental data when trained and tested on their respective stress ratios. Notably, flipped dataset analysis revealed that RF (average error rate = 1.02 %) and NN (average error rate = 1.05 %) models trained on equal stress ratio data effectively predicted critical stress ratio behaviour, showcasing their adaptability. These findings highlight the potential of machine learning-driven approaches for predictive modelling, enabling more efficient material design and optimization under cyclic loading conditions.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108913"},"PeriodicalIF":5.7,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-05DOI: 10.1016/j.ijfatigue.2025.108910
Jiaqiang Dang, Ryuji Yabutani, Sien Liu, Shoichi Nambu
The purpose of the present work was to analyze the microstructure evolution of martensite steel with 0.4C (in mass%) under different heat treatments which were marked as OQ900 and OQ1000, and its effect on fatigue fracture behavior. A crystal plasticity finite element method (CPFEM) was developed to analyze the role of multi-scale structures of lath martensite on fatigue crack initiation, and the fatigue lives of the materials with varying substructures are quantitatively compared. The numerical simulation was verified by fatigue tests where special attention was paid on the peculiarity of crack initiation exposed to the microstructural effect. The fracture surfaces of the steels subjected to both high-cycle fatigue (HCF) and low-cycle fatigue (LCF) regimes were also analyzed. The results indicated that OQ900 sample hold a smaller size in equivalent prior austenite grain, packet and block length than OQ1000 sample, which finally led to a slightly higher bending strength for OQ900 sample. Both inclusions and slipping fractures were found as the origins of fatigue crack initiation in the martensite steels with 0.4C, and especially the latter played a dominant role in HCF regime. In this regard, the difference in fatigue life tended clear as a clue to the effect of microstructure on fatigue behavior in HCF regime. The block morphology and its orientation affected the strain localization in an obvious way, where lower fracture indicator parameters (FIPs) value and longer crack initiation life were obtained in OQ900 sample. The EBSD analysis of fatigue-tested samples showed that the block boundaries were the most preferred sites for crack initiation, which were characterized as persistent slip bands. The crack propagation path was distributed in a deflected manner owing to the inhibition effect of boundaries. Overall, OQ900 sample presents a higher fatigue resistance than OQ1000 in HCF regime when the initiation and early propagation life of fatigue cracks were considered.
{"title":"Microstructure and bending fatigue behavior of martensite steel with 0.4%C subjected to different heat treatments","authors":"Jiaqiang Dang, Ryuji Yabutani, Sien Liu, Shoichi Nambu","doi":"10.1016/j.ijfatigue.2025.108910","DOIUrl":"10.1016/j.ijfatigue.2025.108910","url":null,"abstract":"<div><div>The purpose of the present work was to analyze the microstructure evolution of martensite steel with 0.4C (in mass%) under different heat treatments which were marked as OQ900 and OQ1000, and its effect on fatigue fracture behavior. A crystal plasticity finite element method (CPFEM) was developed to analyze the role of multi-scale structures of lath martensite on fatigue crack initiation, and the fatigue lives of the materials with varying substructures are quantitatively compared. The numerical simulation was verified by fatigue tests where special attention was paid on the peculiarity of crack initiation exposed to the microstructural effect. The fracture surfaces of the steels subjected to both high-cycle fatigue (HCF) and low-cycle fatigue (LCF) regimes were also analyzed. The results indicated that OQ900 sample hold a smaller size in equivalent prior austenite grain, packet and block length than OQ1000 sample, which finally led to a slightly higher bending strength for OQ900 sample. Both inclusions and slipping fractures were found as the origins of fatigue crack initiation in the martensite steels with 0.4C, and especially the latter played a dominant role in HCF regime. In this regard, the difference in fatigue life tended clear as a clue to the effect of microstructure on fatigue behavior in HCF regime. The block morphology and its orientation affected the strain localization in an obvious way, where lower fracture indicator parameters (FIPs) value and longer crack initiation life were obtained in OQ900 sample. The EBSD analysis of fatigue-tested samples showed that the block boundaries were the most preferred sites for crack initiation, which were characterized as persistent slip bands. The crack propagation path was distributed in a deflected manner owing to the inhibition effect of boundaries. Overall, OQ900 sample presents a higher fatigue resistance than OQ1000 in HCF regime when the initiation and early propagation life of fatigue cracks were considered.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108910"},"PeriodicalIF":5.7,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143578450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-04DOI: 10.1016/j.ijfatigue.2025.108903
Jinshan He , Chunfeng Hu , Runze Zhang , Pinpin Hu , Chengbo Xiao , Xitao Wang
The present study proposes a novel physically-based criterion for simultaneously predicting both high-cycle and low-cycle fatigue life by incorporating slip irreversibility. Considering the damage induced by irreversible plastic deformation on the foundation of cumulative dissipation energy, this criterion serves as an effective tool for assessing fatigue life. Based on the construction of multiple RVE models combined with crystal plastic finite element method, we successfully predicted the high- and low-cycle fatigue life of micro-grain K4169 alloy within a scatter band of ± 1.5 by this new fatigue parameter indicator. Notably, the prediction error of high-cycle fatigue life is within 10 %, a 70 % reduction compared to the cumulative dissipated energy criterion. On such basis, the slip irreversible coefficients (p) at different loading conditions were predicated precisely and validated by experimental data obtained from atom force microscope. Then a double logarithmic linear relationship between p and fatigue life of the alloy was established with the equation . In addition, the high-cycle fatigue life of fine-grain K4169 alloy was also precisely predicted within a scatter band of ± 2.5 by adjusting grain size in RVE models.
{"title":"A new low-cycle and high-cycle fatigue life prediction criterion based on crystal plasticity finite element method","authors":"Jinshan He , Chunfeng Hu , Runze Zhang , Pinpin Hu , Chengbo Xiao , Xitao Wang","doi":"10.1016/j.ijfatigue.2025.108903","DOIUrl":"10.1016/j.ijfatigue.2025.108903","url":null,"abstract":"<div><div>The present study proposes a novel physically-based criterion for simultaneously predicting both high-cycle and low-cycle fatigue life by incorporating slip irreversibility. Considering the damage induced by irreversible plastic deformation on the foundation of cumulative dissipation energy, this criterion serves as an effective tool for assessing fatigue life. Based on the construction of multiple RVE models combined with crystal plastic finite element method, we successfully predicted the high- and low-cycle fatigue life of micro-grain K4169 alloy within a scatter band of ± 1.5 by this new fatigue parameter indicator. Notably, the prediction error of high-cycle fatigue life is within 10 %, a 70 % reduction compared to the cumulative dissipated energy criterion. On such basis, the slip irreversible coefficients (<em>p</em>) at different loading conditions were predicated precisely and validated by experimental data obtained from atom force microscope. Then a double logarithmic linear relationship between <em>p</em> and fatigue life of the alloy was established with the equation <span><math><mrow><mi>p</mi><mo>=</mo><mn>1.2</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>-</mo><mn>3</mn></mrow></msup><mo>∙</mo><msubsup><mi>N</mi><mrow><mi>f</mi></mrow><mrow><mo>-</mo><mn>0.4079</mn></mrow></msubsup></mrow></math></span>. In addition, the high-cycle fatigue life of fine-grain K4169 alloy was also precisely predicted within a scatter band of ± 2.5 by adjusting grain size in RVE models.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108903"},"PeriodicalIF":5.7,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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