Pub Date : 2026-01-28DOI: 10.1016/j.engfracmech.2026.111900
Thu Hien Tran , Hung Thanh Tran , Tinh Quoc Bui
This paper introduces an efficient local damage framework for numerically analyzing time-dependent crack growth in brittle and quasi-brittle materials under dynamic loading. The core of the approach utilizes a classical scalar damage model with an explicit dynamic solver and an energy-based regularization technique to circumvent mesh dependency while avoiding high computational costs. In fact, using the explicit solver for isotropic damage theory requires no system of equations to be solved; all calculations are performed through straightforward updates of the kinematic fields, history variables, and local damage variables, without any matrix inversion. We compare the performance of four different equivalent strain measures including the smooth Rankine, modified von Mises, enhanced bi-energy norm, and Mazars to identify the most suitable models for predicting dynamic fracture phenomena like mixed-mode shearing, crack branching, and fragmentation in two-dimensional and three-dimensional solids. The results show that the smooth Rankine norm demonstrates the best compatibility across challenging fracture problems. The modified von Mises and enhanced bi-energy norms also perform well when properly parameterized. In contrast, the Mazars strain norm shows notable limitations.
{"title":"On the role of damage driving forces in scalar damage models for dynamic crack growth in 2D and 3D media","authors":"Thu Hien Tran , Hung Thanh Tran , Tinh Quoc Bui","doi":"10.1016/j.engfracmech.2026.111900","DOIUrl":"10.1016/j.engfracmech.2026.111900","url":null,"abstract":"<div><div>This paper introduces an efficient local damage framework for numerically analyzing time-dependent crack growth in brittle and quasi-brittle materials under dynamic loading. The core of the approach utilizes a classical scalar damage model with an explicit dynamic solver and an energy-based regularization technique to circumvent mesh dependency while avoiding high computational costs. In fact, using the explicit solver for isotropic damage theory requires no system of equations to be solved; all calculations are performed through straightforward updates of the kinematic fields, history variables, and local damage variables, without any matrix inversion. We compare the performance of four different equivalent strain measures including the smooth Rankine, modified von Mises, enhanced bi-energy norm, and Mazars to identify the most suitable models for predicting dynamic fracture phenomena like mixed-mode shearing, crack branching, and fragmentation in two-dimensional and three-dimensional solids. The results show that the smooth Rankine norm demonstrates the best compatibility across challenging fracture problems. The modified von Mises and enhanced bi-energy norms also perform well when properly parameterized. In contrast, the Mazars strain norm shows notable limitations.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111900"},"PeriodicalIF":5.3,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-28DOI: 10.1016/j.engfracmech.2026.111885
Feifei Qin, Shiming Dong
Fracture is one of engineering materials’ most critical failure modes, directly threatening structural safety and stability. Accurate prediction of crack propagation behaviour is crucial for the reliable design and extended service life of engineering structures. To address the limitations of traditional numerical approaches in capturing complex crack topologies, this study develops an improved phase-field model that incorporates the critical energy release rate (CERR) derived from the weight function method for Brazilian disk specimens under non-uniform compressive loading. A staggered scheme decouples elastic deformation from fracture evolution, ensuring stability and efficiency. The model is validated by strong agreement between simulated and experimental load–displacement responses and strain energy evolution. System simulations investigated the effects of loading angle on strain energy evolution, crack initiation angle, crack propagation trajectory, and damage accumulation. Results reveal that loading angle critically influences crack morphology and structural capacity, with larger angles enhancing shear contributions and promoting mixed-mode fracture. These findings advance the theoretical understanding of fracture in brittle materials and establish a reliable predictive framework for evaluating and optimizing fracture resistance in engineering applications.
{"title":"An improved phase-field model incorporating the critical energy release rate for simulating damage evolution in cracked Brazilian disks under non-uniform compressive loading","authors":"Feifei Qin, Shiming Dong","doi":"10.1016/j.engfracmech.2026.111885","DOIUrl":"10.1016/j.engfracmech.2026.111885","url":null,"abstract":"<div><div>Fracture is one of engineering materials’ most critical failure modes, directly threatening structural safety and stability. Accurate prediction of crack propagation behaviour is crucial for the reliable design and extended service life of engineering structures. To address the limitations of traditional numerical approaches in capturing complex crack topologies, this study develops an improved phase-field model that incorporates the critical energy release rate (CERR) derived from the weight function method for Brazilian disk specimens under non-uniform compressive loading. A staggered scheme decouples elastic deformation from fracture evolution, ensuring stability and efficiency. The model is validated by strong agreement between simulated and experimental load–displacement responses and strain energy evolution. System simulations investigated the effects of loading angle on strain energy evolution, crack initiation angle, crack propagation trajectory, and damage accumulation. Results reveal that loading angle critically influences crack morphology and structural capacity, with larger angles enhancing shear contributions and promoting mixed-mode fracture. These findings advance the theoretical understanding of fracture in brittle materials and establish a reliable predictive framework for evaluating and optimizing fracture resistance in engineering applications.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111885"},"PeriodicalIF":5.3,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146185545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-27DOI: 10.1016/j.engfracmech.2026.111899
Hiroshi Yoshihara, Makoto Maruta
Mode I/II combined fracture behavior of western hemlock was characterized using asymmetrical four-point fracture (AFPF) tests on side-grooved samples. The Mode I/II combination ratios were controlled by horizontally shifting the crack location in the sample, and the Mode I/II initiation stress intensity factors (SIFs) were determined under various combination ratios. In addition, mixed-mode bending (MMB) tests were conducted to validate the AFPF results. The relationships between the Mode I and Mode II critical SIFs characterized from both the AFPF and MMB tests could be approximated into elliptical functions, indicating that the AFPF test is effective for obtaining initiation SIFs under Mode I/II combined fracture conditions. When the characterization is limited to initiation SIFs, the AFPF test is more advantageous than the MMB test because the Mode I/II combination ratios can be varied more easily without large-scale equipment inevitably required for the MMB testing.
{"title":"Mode I/II-combined fracture condition of western hemlock characterized using an asymmetrical four-point fracture test of a side-grooved sample","authors":"Hiroshi Yoshihara, Makoto Maruta","doi":"10.1016/j.engfracmech.2026.111899","DOIUrl":"10.1016/j.engfracmech.2026.111899","url":null,"abstract":"<div><div>Mode I/II combined fracture behavior of western hemlock was characterized using asymmetrical four-point fracture (AFPF) tests on side-grooved samples. The Mode I/II combination ratios were controlled by horizontally shifting the crack location in the sample, and the Mode I/II initiation stress intensity factors (SIFs) were determined under various combination ratios. In addition, mixed-mode bending (MMB) tests were conducted to validate the AFPF results. The relationships between the Mode I and Mode II critical SIFs characterized from both the AFPF and MMB tests could be approximated into elliptical functions, indicating that the AFPF test is effective for obtaining initiation SIFs under Mode I/II combined fracture conditions. When the characterization is limited to initiation SIFs, the AFPF test is more advantageous than the MMB test because the Mode I/II combination ratios can be varied more easily without large-scale equipment inevitably required for the MMB testing.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111899"},"PeriodicalIF":5.3,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-27DOI: 10.1016/j.engfracmech.2026.111867
Yipeng Rao , Quanzhang Li , Zhiqiang Yang , Meizhen Xiang
Based on the two-scale asymptotic expansion theory, we establish a dynamic fracture model for 3D micro-cracked materials which extends the previous 2D results presented by the authors in Rao (2022); Rao et al. (2023). Using the two-scale theory for 3D problems, an analytical formulation of dynamic energy release rate is obtained that includes additive contributions of macroscopic strain, strain gradient and strain rate. The coefficients of the strain, strain gradient and strain rate are related to the microstructural size and derivatives of the homogenized (effective) elastodynamics moduli, which are determined by solutions of elementary elastodynamics problems defined in a reference unit cell. The microdamage evolution equation is developed by combining the analytical formulation of dynamic energy release rate with the Griffith fracture law. In contrast to the two-dimensional case where the normalized microcrack length is used as the measure of microdamage, in the three-dimensional case, the normalized microcrack area is used as the measure of microdamage, and then, the dynamic evolution equation of the microdamage variable for 3D problems has the same form as that for 2D cases. We analyze the properties of the homogenized elastodynamics moduli and compare them with those in the 2D cases. The coupling of microstructure size, strain gradient and strain rate are analyzed by examining local material responses and spallation experiment. The finite element simulations based on the model are well validated against available experimental results and previous reports.
{"title":"A 3D brittle fracture model with effect of microstructure, strain gradient and strain rate","authors":"Yipeng Rao , Quanzhang Li , Zhiqiang Yang , Meizhen Xiang","doi":"10.1016/j.engfracmech.2026.111867","DOIUrl":"10.1016/j.engfracmech.2026.111867","url":null,"abstract":"<div><div>Based on the two-scale asymptotic expansion theory, we establish a dynamic fracture model for 3D micro-cracked materials which extends the previous 2D results presented by the authors in Rao (2022); Rao et al. (2023). Using the two-scale theory for 3D problems, an analytical formulation of dynamic energy release rate is obtained that includes additive contributions of macroscopic strain, strain gradient and strain rate. The coefficients of the strain, strain gradient and strain rate are related to the microstructural size and derivatives of the homogenized (effective) elastodynamics moduli, which are determined by solutions of elementary elastodynamics problems defined in a reference unit cell. The microdamage evolution equation is developed by combining the analytical formulation of dynamic energy release rate with the Griffith fracture law. In contrast to the two-dimensional case where the normalized microcrack length is used as the measure of microdamage, in the three-dimensional case, the normalized microcrack area is used as the measure of microdamage, and then, the dynamic evolution equation of the microdamage variable for 3D problems has the same form as that for 2D cases. We analyze the properties of the homogenized elastodynamics moduli and compare them with those in the 2D cases. The coupling of microstructure size, strain gradient and strain rate are analyzed by examining local material responses and spallation experiment. The finite element simulations based on the model are well validated against available experimental results and previous reports.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111867"},"PeriodicalIF":5.3,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-27DOI: 10.1016/j.engfracmech.2026.111879
Yanan Zhang , Xin Cai , Xudong Chen , Xingwen Guo
To investigate the effect of different interlayer interface structures on the fracture behavior of Cemented granular materials (CGM) this study prepared three types of interlayer interface specimens untreated mortar and neat paste and conducted three-point bending fracture tests acoustic emission (AE) technology and 3D scanning technology to systematically analyze the entire fracture process of the interlayer interface in CGM. The results indicate that interlayer interface treatment significantly alters the fracture behavior of cemented granular materials with untreated interfaces exhibiting brittle failure while cement mortar and neat paste treatments enhance the bond strength and overall toughness of the interface delaying crack propagation and improving crack resistance. The neat paste-treated interface exhibits a lower initial -value, a steady increase in the -value, and a trend dominated by low-frequency main frequencies, indicating more coordinated microcrack propagation and a more stable interface structure. RA–AF parameters and Gaussian Mixture Model (GMM) clustering analysis show that, after neat paste and mortar treatments, the proportions of tensile cracks are 25.1% and 17.7%, respectively, and the consistency of crack propagation is enhanced. 3D scanning results show that the treated interface has more uniform bond strength and smoother crack propagation especially neat paste treatment effectively suppresses brittle fracture and improves fracture resistance This study provides theoretical support for optimizing interlayer interface treatment in cemented granular material dams and reveals the critical role of interface structure in the fracture process of cemented granular materials.
{"title":"Multiscale analysis of the entire fracture process of cemented granular materials Considering structural differences in the interlayer interfaces","authors":"Yanan Zhang , Xin Cai , Xudong Chen , Xingwen Guo","doi":"10.1016/j.engfracmech.2026.111879","DOIUrl":"10.1016/j.engfracmech.2026.111879","url":null,"abstract":"<div><div>To investigate the effect of different interlayer interface structures on the fracture behavior of Cemented granular materials (CGM) this study prepared three types of interlayer interface specimens untreated mortar and neat paste and conducted three-point bending fracture tests acoustic emission (AE) technology and 3D scanning technology to systematically analyze the entire fracture process of the interlayer interface in CGM. The results indicate that interlayer interface treatment significantly alters the fracture behavior of cemented granular materials with untreated interfaces exhibiting brittle failure while cement mortar and neat paste treatments enhance the bond strength and overall toughness of the interface delaying crack propagation and improving crack resistance. The neat paste-treated interface exhibits a lower initial <span><math><mi>b</mi></math></span>-value, a steady increase in the <span><math><mi>b</mi></math></span>-value, and a trend dominated by low-frequency main frequencies, indicating more coordinated microcrack propagation and a more stable interface structure. RA–AF parameters and Gaussian Mixture Model (GMM) clustering analysis show that, after neat paste and mortar treatments, the proportions of tensile cracks are 25.1% and 17.7%, respectively, and the consistency of crack propagation is enhanced. 3D scanning results show that the treated interface has more uniform bond strength and smoother crack propagation especially neat paste treatment effectively suppresses brittle fracture and improves fracture resistance This study provides theoretical support for optimizing interlayer interface treatment in cemented granular material dams and reveals the critical role of interface structure in the fracture process of cemented granular materials.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111879"},"PeriodicalIF":5.3,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-25DOI: 10.1016/j.engfracmech.2026.111871
Hui Huang , Yanli Wang , Jian Chen , Yongbing Li , Zhili Feng
Welding residual stresses especially the high tensile stresses are proved to have negative impacts on the fatigue and fracture behaviors of welded structures. In this study, a virtual fabrication of test specimens from welding process to specimen preparation was carried out by numerical simulation. An austenitic stainless steel multi-pass pipe welding was simulated by transient thermal–mechanical finite element analysis, the residual stresses were then mapped into the test specimen to evaluate fracture toughness. The findings in this study confirmed that, residual stress can be high in a sub-sized compact tensile specimen, which may accelerate or hinder the crack propagation during actual fatigue and fracture tests as reported in recent years. The influence of the cutting location and orientation of the specimen on fracture performance was investigated systematically to provide a fundamental understanding of welding residual stress and necessary insights into the specimen preparation procedure. Considering the limitation of measuring techniques and the complexity of the stress distribution, the developed numerical model can be a very useful tool to elucidate the stress evolution and quantify the effect of remaining welding stress on fracture toughness.
{"title":"On the roles of welding residual stresses in determination of fracture toughness in austenitic stainless steel SUS 304 pipeline girth welds","authors":"Hui Huang , Yanli Wang , Jian Chen , Yongbing Li , Zhili Feng","doi":"10.1016/j.engfracmech.2026.111871","DOIUrl":"10.1016/j.engfracmech.2026.111871","url":null,"abstract":"<div><div>Welding residual stresses especially the high tensile stresses are proved to have negative impacts on the fatigue and fracture behaviors of welded structures. In this study, a virtual fabrication of test specimens from welding process to specimen preparation was carried out by numerical simulation. An austenitic stainless steel multi-pass pipe welding was simulated by transient thermal–mechanical finite element analysis, the residual stresses were then mapped into the test specimen to evaluate fracture toughness. The findings in this study confirmed that, residual stress can be high in a sub-sized compact tensile specimen, which may accelerate or hinder the crack propagation during actual fatigue and fracture tests as reported in recent years. The influence of the cutting location and orientation of the specimen on fracture performance was investigated systematically to provide a fundamental understanding of welding residual stress and necessary insights into the specimen preparation procedure. Considering the limitation of measuring techniques and the complexity of the stress distribution, the developed numerical model can be a very useful tool to elucidate the stress evolution and quantify the effect of remaining welding stress on fracture toughness.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111871"},"PeriodicalIF":5.3,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-24DOI: 10.1016/j.engfracmech.2026.111893
Marcela Gimenes, Osvaldo L. Manzoli
The internal structure of concrete consists of aggregates, cement mortar, and weak interfaces distributed at the mesoscopic level, which strongly influence its quasi-brittle mechanical behavior. Recycled aggregate concrete (RAC) presents an even more heterogeneous mesostructure, making the prediction of its compressive failure particularly challenging.
A novel three-dimensional extension of the mesoscale modeling framework based on the mesh fragmentation technique (MFT) is proposed. Within this fully continuum approach, high-aspect-ratio interface elements (HAR-IEs) are inserted into the finite element mesh to define potential crack paths. A new two-layer condensed HAR-IE is introduced, governed by tensile and shear-frictional constitutive models, allowing the simulation of compressive failure as a combination of both mechanisms with reduced computational cost.
The proposed framework is general and can be applied to concretes containing aggregates of different origins or mechanical properties. Here, it is demonstrated through its application to RAC, for which fracture may propagate through the recycled aggregates themselves.
Numerical uniaxial compression tests were performed on mortar, natural aggregate concrete (NAC), and RAC specimens. The numerical results are in good agreement with experimental data, capturing stress–strain behavior, fracture patterns, and the influence of recycled aggregate content (0%, 50%, and 100%) on stiffness and dilatancy. The proposed approach provides a physically consistent and computationally efficient tool for studying compressive fracture in mesoscale concrete. It marks a significant advancement over previous 2D implementations by enabling the simulation of fully three-dimensional stress redistribution and failure evolution.
{"title":"A novel mesh-fragmentation-based mesoscale approach for modeling compressive fracture in concrete with application to recycled aggregate concrete","authors":"Marcela Gimenes, Osvaldo L. Manzoli","doi":"10.1016/j.engfracmech.2026.111893","DOIUrl":"10.1016/j.engfracmech.2026.111893","url":null,"abstract":"<div><div>The internal structure of concrete consists of aggregates, cement mortar, and weak interfaces distributed at the mesoscopic level, which strongly influence its quasi-brittle mechanical behavior. Recycled aggregate concrete (RAC) presents an even more heterogeneous mesostructure, making the prediction of its compressive failure particularly challenging.</div><div>A novel three-dimensional extension of the mesoscale modeling framework based on the mesh fragmentation technique (MFT) is proposed. Within this fully continuum approach, high-aspect-ratio interface elements (HAR-IEs) are inserted into the finite element mesh to define potential crack paths. A new two-layer condensed HAR-IE is introduced, governed by tensile and shear-frictional constitutive models, allowing the simulation of compressive failure as a combination of both mechanisms with reduced computational cost.</div><div>The proposed framework is general and can be applied to concretes containing aggregates of different origins or mechanical properties. Here, it is demonstrated through its application to RAC, for which fracture may propagate through the recycled aggregates themselves.</div><div>Numerical uniaxial compression tests were performed on mortar, natural aggregate concrete (NAC), and RAC specimens. The numerical results are in good agreement with experimental data, capturing stress–strain behavior, fracture patterns, and the influence of recycled aggregate content (0%, 50%, and 100%) on stiffness and dilatancy. The proposed approach provides a physically consistent and computationally efficient tool for studying compressive fracture in mesoscale concrete. It marks a significant advancement over previous 2D implementations by enabling the simulation of fully three-dimensional stress redistribution and failure evolution.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111893"},"PeriodicalIF":5.3,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-24DOI: 10.1016/j.engfracmech.2026.111883
Hui Wei , Yunyao Liu , Jue Li , Feiyue Wang , Jianlong Zheng , Yinhan Dai
A clear understanding of the evolution, mechanisms, and stage-wise progression of low-temperature fatigue cracking in asphalt mixtures is essential for interpreting fatigue failure and improving pavement durability. This study employs acoustic emission (AE) monitoring to track the real-time fatigue-damage evolution of pre-notched asphalt mixtures subjected to four sub-zero temperatures (−5, −10, −15, and −20 °C). Stage-dependent behaviors of six AE parameters—b-value, activity S value, rise angle (RA), average frequency (AF), master frequency (MF), and average frequency centroid (AFG)—were quantified to extract precursor signatures of damage states. These multivariate features were further integrated with ensemble-learning algorithms to develop an AE-based damage-state identification framework. Results reveal consistent correspondence between AE-parameter evolution and the four damage stages (void compaction, micro-crack initiation/stable propagation, crack coalescence/unstable propagation, and complete fracture) across all temperatures. Specifically, the b-value exhibits a step-wise decline during crack coalescence, the S value maintains pronounced high-level fluctuations prior to fracture, and the coupled variations in RA, AF, MF, and AFG capture the transition in dominant damage behavior during late-stage evolution. Based on these precursor characteristics, classifiers built using AdaBoost, XGBoost, and Random Forest achieved accurate late-stage identification, with test-set accuracies of 95.4%, 94.2%, and 94.2% and corresponding AUC values of 0.956, 0.978, and 0.970. In addition, the models demonstrated strong precision–recall performance under class imbalance, achieving PR-AUC values of 0.996 (AdaBoost), 0.998 (XGBoost), and 0.998 (Random Forest). Feature-importance analysis further indicates that the S value and b-value are the most influential predictors for damage-state recognition. Overall, the proposed framework provides an interpretable and practical approach for stage-wise identification of low-temperature fatigue damage and supports the development of real-time early-warning strategies for asphalt pavements.
{"title":"Identification of low-temperature fatigue damage states in asphalt mixtures using multivariate acoustic emission parameters","authors":"Hui Wei , Yunyao Liu , Jue Li , Feiyue Wang , Jianlong Zheng , Yinhan Dai","doi":"10.1016/j.engfracmech.2026.111883","DOIUrl":"10.1016/j.engfracmech.2026.111883","url":null,"abstract":"<div><div>A clear understanding of the evolution, mechanisms, and stage-wise progression of low-temperature fatigue cracking in asphalt mixtures is essential for interpreting fatigue failure and improving pavement durability. This study employs acoustic emission (AE) monitoring to track the real-time fatigue-damage evolution of pre-notched asphalt mixtures subjected to four sub-zero temperatures (−5, −10, −15, and −20 °C). Stage-dependent behaviors of six AE parameters—b-value, activity S value, rise angle (RA), average frequency (AF), master frequency (MF), and average frequency centroid (AFG)—were quantified to extract precursor signatures of damage states. These multivariate features were further integrated with ensemble-learning algorithms to develop an AE-based damage-state identification framework. Results reveal consistent correspondence between AE-parameter evolution and the four damage stages (void compaction, micro-crack initiation/stable propagation, crack coalescence/unstable propagation, and complete fracture) across all temperatures. Specifically, the b-value exhibits a step-wise decline during crack coalescence, the S value maintains pronounced high-level fluctuations prior to fracture, and the coupled variations in RA, AF, MF, and AFG capture the transition in dominant damage behavior during late-stage evolution. Based on these precursor characteristics, classifiers built using AdaBoost, XGBoost, and Random Forest achieved accurate late-stage identification, with test-set accuracies of 95.4%, 94.2%, and 94.2% and corresponding AUC values of 0.956, 0.978, and 0.970. In addition, the models demonstrated strong precision–recall performance under class imbalance, achieving PR-AUC values of 0.996 (AdaBoost), 0.998 (XGBoost), and 0.998 (Random Forest). Feature-importance analysis further indicates that the S value and b-value are the most influential predictors for damage-state recognition. Overall, the proposed framework provides an interpretable and practical approach for stage-wise identification of low-temperature fatigue damage and supports the development of real-time early-warning strategies for asphalt pavements.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111883"},"PeriodicalIF":5.3,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-23DOI: 10.1016/j.engfracmech.2026.111886
Dianen Wei , Guansuo Dui , Zhenyu Sun , Yanhui Xi , Zibing Zheng
Void defects and bedding-related anisotropy govern the stability of limestone rock masses under blasting, tunneling, and mining disturbances. To elucidate the instability mechanism and thermo‑mechanical coupling of bedded limestone containing a central circular hole, we performed instrumented drop‑hammer tests while systematically varying impact velocity and bedding angle. High‑speed imaging and infrared thermography were used to quantify infrared radiation temperature (IRT), energy partitioning, and their spatiotemporal coupling with fracture evolution. Damage evolved nonlinearly through five stages—initial loading, loading plateau, main failure, secondary response, and residual vibration. With increasing impact velocity, the plastic zone expanded and limited further force growth; elastic strain‑energy storage was constrained, the hardening–softening process accelerated, and the characteristic double peak in the mechanical response collapsed toward the first peak. Crack nucleation and rapid growth occurred within a very short window early in loading: while overall displacement was still rising, local stresses reached critical levels and triggered rupture. Impact velocity and bedding angle acted jointly on the IRT response; at a bedding angle near 60°, both the temperature peak and the thermal response were greatest, indicating a critical orientation prone to heat localization and structural damage. The stress time history was tightly coupled with temperature rise: during stress accumulation, the temperature‑rise rate reflected crack initiation and frictional heating. Infrared hotspots were spatially congruent with crack trajectories but lagged in time, consistent with a “path → thermal band” evolution; stress redistribution and cooperative branching rendered the local temperature field multi‑lobed with a pronounced bedding‑parallel bias. These results provide a geology‑informed thermographic diagnostic for hole‑affected, bedded limestones and support early‑warning and design decisions in blasting, excavation, and tunneling.
{"title":"Coupled infrared–mechanical signatures of crack evolution in anisotropic limestone with a hole","authors":"Dianen Wei , Guansuo Dui , Zhenyu Sun , Yanhui Xi , Zibing Zheng","doi":"10.1016/j.engfracmech.2026.111886","DOIUrl":"10.1016/j.engfracmech.2026.111886","url":null,"abstract":"<div><div>Void defects and bedding-related anisotropy govern the stability of limestone rock masses under blasting, tunneling, and mining disturbances. To elucidate the instability mechanism and thermo‑mechanical coupling of bedded limestone containing a central circular hole, we performed instrumented drop‑hammer tests while systematically varying impact velocity and bedding angle. High‑speed imaging and infrared thermography were used to quantify infrared radiation temperature (IRT), energy partitioning, and their spatiotemporal coupling with fracture evolution. Damage evolved nonlinearly through five stages—initial loading, loading plateau, main failure, secondary response, and residual vibration. With increasing impact velocity, the plastic zone expanded and limited further force growth; elastic strain‑energy storage was constrained, the hardening–softening process accelerated, and the characteristic double peak in the mechanical response collapsed toward the first peak. Crack nucleation and rapid growth occurred within a very short window early in loading: while overall displacement was still rising, local stresses reached critical levels and triggered rupture. Impact velocity and bedding angle acted jointly on the IRT response; at a bedding angle near 60°, both the temperature peak and the thermal response were greatest, indicating a critical orientation prone to heat localization and structural damage. The stress time history was tightly coupled with temperature rise: during stress accumulation, the temperature‑rise rate reflected crack initiation and frictional heating. Infrared hotspots were spatially congruent with crack trajectories but lagged in time, consistent with a “path → thermal band” evolution; stress redistribution and cooperative branching rendered the local temperature field multi‑lobed with a pronounced bedding‑parallel bias. These results provide a geology‑informed thermographic diagnostic for hole‑affected, bedded limestones and support early‑warning and design decisions in blasting, excavation, and tunneling.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111886"},"PeriodicalIF":5.3,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding ductile fracture behaviors of high-strength structural steel is essential for safe and efficient design of modern infrastructures. This study focused on fracture mechanisms and internal void evolution during ductile fracture of Q550 high-strength structural steel using in-situ X-ray computed tomography (CT) integrated with digital volume correlation (DVC) techniques. The results demonstrate that fracture is governed by void nucleation, growth, and coalescence, driven by significant strain localization around big voids after necking. A progressive increase in porosity from 0.006‰ to 0.96‰ within the region of interest (ROI), with over 95% of voids nucleating in the post-necking stage. The evolution of voids is strongly dependent on local plastic strain. Voids within the strain-concentrated necking region undergo significant volumetric growth and morphological change, while those outside remain nearly spherical. Incremental DVC analyses quantify this strain localization and reveal concurrent damage accumulation within the necking center and elastic unloading in surrounding regions in the post-necking stage. In the final stage before fracture, local strain in the necking center exceeds 25%, far above the global average of 14.7%. The resulting high stress triaxiality promotes multi-directional void growth (in the X-, Y-, and Z-axis directions) and facilitates coalescence, initiating transverse micro-cracks that progressively reduce the load-bearing cross-section. Fractographic analysis of the cup-and-cone morphology confirms a void-mediated mechanism, with dimples in the central fibrous zone providing direct evidence of coalescence preceding final failure. This work elucidates the intrinsic link between macroscopic strain localization, microscopic void evolution, and the ultimate ductile fracture in high-strength steel.
{"title":"Micro-mechanisms of ductile fracture in Q550 high-strength structural steel using X-ray μCT integrated with digital volume correlation (DVC)","authors":"Bo-chuan Jiang , Xin-yang Gao , Zhao-xia Qu , Liang-jiu Jia","doi":"10.1016/j.engfracmech.2026.111884","DOIUrl":"10.1016/j.engfracmech.2026.111884","url":null,"abstract":"<div><div>Understanding ductile fracture behaviors of high-strength structural steel is essential for safe and efficient design of modern infrastructures. This study focused on fracture mechanisms and internal void evolution during ductile fracture of Q550 high-strength structural steel using in-situ X-ray computed tomography (CT) integrated with digital volume correlation (DVC) techniques. The results demonstrate that fracture is governed by void nucleation, growth, and coalescence, driven by significant strain localization around big voids after necking. A progressive increase in porosity from 0.006‰ to 0.96‰ within the region of interest (ROI), with over 95% of voids nucleating in the post-necking stage. The evolution of voids is strongly dependent on local plastic strain. Voids within the strain-concentrated necking region undergo significant volumetric growth and morphological change, while those outside remain nearly spherical. Incremental DVC analyses quantify this strain localization and reveal concurrent damage accumulation within the necking center and elastic unloading in surrounding regions in the post-necking stage. In the final stage before fracture, local strain in the necking center exceeds 25%, far above the global average of 14.7%. The resulting high stress triaxiality promotes multi-directional void growth (in the X-, Y-, and Z-axis directions) and facilitates coalescence, initiating transverse micro-cracks that progressively reduce the load-bearing cross-section. Fractographic analysis of the cup-and-cone morphology confirms a void-mediated mechanism, with dimples in the central fibrous zone providing direct evidence of coalescence preceding final failure. This work elucidates the intrinsic link between macroscopic strain localization, microscopic void evolution, and the ultimate ductile fracture in high-strength steel.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111884"},"PeriodicalIF":5.3,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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