Pub Date : 2026-03-11Epub 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":"2026-03-11","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 : 2026-03-11Epub 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":"2026-03-11","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}
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":"2026-03-11","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}
Pub Date : 2026-03-11Epub 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":"2026-03-11","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 : 2026-03-11Epub Date: 2026-01-22DOI: 10.1016/j.engfracmech.2026.111880
Yan-bing Wang , Dai-rui Fu , Xiao-yan Zhao , Xiao-guang Zhou , Qing-wen Li , Xiao Wang , Tie-jun Tao
To address the unresolved damage mechanisms and unclear fracture propagation laws of jointed rock masses subjected to gas-expansion-induced rock breaking, a series of liquid-oxygen phase-transition fracturing model tests combined with X-ray CT–based three-dimensional reconstruction were conducted. The damage evolution characteristics of rock masses with different structural configurations under high-pressure gas loading were systematically investigated, and the dynamic propagation behavior and three-dimensional spatial distribution of blast-induced fractures were revealed. The results indicate that the joint inclination angle reconstructs the energy distribution pattern by regulating the reflection–refraction behavior of stress waves. With increasing joint inclination, the strain response exhibits alternating tensile–compressive characteristics, manifested by enhanced tensile strain peaks and attenuated compressive strain peaks, which in turn drive the systematic evolution of fracture geometric parameters: the average fracture width increases monotonically, the average fracture orientation angle continuously decreases, while the surface density and crushed-zone area show pronounced nonlinear variations. Fracture network parameters respond in a differentiated manner: the fracture surface area, fracture volume, and fracture ratio reach peak values at specific inclination angles, whereas fracture length, width, and equivalent diameter increase monotonically. Furthermore, a coupled damage–porosity heterogeneity characterization index is proposed, quantitatively revealing the nonlinear decay laws of the volumetric fractal dimension and damage degree under the gradient control of joint inclination. This index effectively characterizes the coupling mechanism between damage propagation and pore structure evolution in jointed rock masses subjected to gas-driven fracturing.
{"title":"Analysis of damage and fracture mechanisms in quartzite with different inclination angles under liquid oxygen phase change-induced fracturing","authors":"Yan-bing Wang , Dai-rui Fu , Xiao-yan Zhao , Xiao-guang Zhou , Qing-wen Li , Xiao Wang , Tie-jun Tao","doi":"10.1016/j.engfracmech.2026.111880","DOIUrl":"10.1016/j.engfracmech.2026.111880","url":null,"abstract":"<div><div>To address the unresolved damage mechanisms and unclear fracture propagation laws of jointed rock masses subjected to gas-expansion-induced rock breaking, a series of liquid-oxygen phase-transition fracturing model tests combined with X-ray CT–based three-dimensional reconstruction were conducted. The damage evolution characteristics of rock masses with different structural configurations under high-pressure gas loading were systematically investigated, and the dynamic propagation behavior and three-dimensional spatial distribution of blast-induced fractures were revealed. The results indicate that the joint inclination angle reconstructs the energy distribution pattern by regulating the reflection–refraction behavior of stress waves. With increasing joint inclination, the strain response exhibits alternating tensile–compressive characteristics, manifested by enhanced tensile strain peaks and attenuated compressive strain peaks, which in turn drive the systematic evolution of fracture geometric parameters: the average fracture width increases monotonically, the average fracture orientation angle continuously decreases, while the surface density and crushed-zone area show pronounced nonlinear variations. Fracture network parameters respond in a differentiated manner: the fracture surface area, fracture volume, and fracture ratio reach peak values at specific inclination angles, whereas fracture length, width, and equivalent diameter increase monotonically. Furthermore, a coupled damage–porosity heterogeneity characterization index is proposed, quantitatively revealing the nonlinear decay laws of the volumetric fractal dimension and damage degree under the gradient control of joint inclination. This index effectively characterizes the coupling mechanism between damage propagation and pore structure evolution in jointed rock masses subjected to gas-driven fracturing.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111880"},"PeriodicalIF":5.3,"publicationDate":"2026-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076007","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 : 2026-03-11Epub Date: 2026-01-23DOI: 10.1016/j.engfracmech.2026.111876
Peinan Wu , Qiang Zhang , Kai Huang , YueJin Zhou , HaiXu Xu , Kai Wang
The mechanical response of the roof and coal seam is important to the stability control in coal mining engineering. Given the nonlinear evolution of overburden pressure and the variation in coal seam stiffness caused by mining, the roof-coal seam was discretized into a series of smaller segments, characterized by linear roof pressure and constant foundation stiffness. The analytical solutions for the mechanical response of each segment were derived using the governing equations for the initial and periodically fractured roof. Using an iterative numerical algorithm, integral coefficients and exact foundation stiffness values were determined based on the evolution of progressive degradation in coal seam stiffness. The theoretical results show good agreement with existing numerical and analytical solutions. The degradation of coal seam stiffness leads to a non-monotonic evolution of bearing pressure, initially increasing, followed by a decrease, which aligns closely with field-monitored data. The sensitivity analysis further revealed that overburden pressure, roof thickness, and coal seam thickness exert a significant influence on deflection and internal forces of the roof. The proposed solution offers theoretical guidance for safety evaluation and hydraulic support design in longwall mining.
{"title":"Analytical solutions for the initial and periodic fracture of hard roof in longwall mining considering progressive deterioration of coal seam stiffness","authors":"Peinan Wu , Qiang Zhang , Kai Huang , YueJin Zhou , HaiXu Xu , Kai Wang","doi":"10.1016/j.engfracmech.2026.111876","DOIUrl":"10.1016/j.engfracmech.2026.111876","url":null,"abstract":"<div><div>The mechanical response of the roof and coal seam is important to the stability control in coal mining engineering. Given the nonlinear evolution of overburden pressure and the variation in coal seam stiffness caused by mining, the roof-coal seam was discretized into a series of smaller segments, characterized by linear roof pressure and constant foundation stiffness. The analytical solutions for the mechanical response of each segment were derived using the governing equations for the initial and periodically fractured roof. Using an iterative numerical algorithm, integral coefficients and exact foundation stiffness values were determined based on the evolution of progressive degradation in coal seam stiffness. The theoretical results show good agreement with existing numerical and analytical solutions. The degradation of coal seam stiffness leads to a non-monotonic evolution of bearing pressure, initially increasing, followed by a decrease, which aligns closely with field-monitored data. The sensitivity analysis further revealed that overburden pressure, roof thickness, and coal seam thickness exert a significant influence on deflection and internal forces of the roof. The proposed solution offers theoretical guidance for safety evaluation and hydraulic support design in longwall mining.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111876"},"PeriodicalIF":5.3,"publicationDate":"2026-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076010","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 : 2026-03-11Epub Date: 2026-01-20DOI: 10.1016/j.engfracmech.2026.111874
S.I. Okocha , M.T. Hendry , P.Y.B. Jar
This study investigates the fracture toughness (KJC) and hardness of heat-treated, cold-drawn AISI 4140 alloy (“e.t.d” 150) alongside three representative rail steels (JP, EV, and CZ) to comparatively evaluate their mechanical performance. Importance is placed on “e.t.d” 150 to assess its potentiality as a viable alternative material for rail steel applications based on current insights to rail steel material recycling and substitution. Fracture toughness (KJC) was assessed using a chamfered cylindrical flat-end and spherical indenter based on a novel virtual J-integral approach that minimizes the plastic J-integral component based on Irwin’s elastic solution, while hardness was obtained using only spherical indentation. A comparison between the KJC outcomes of both indenters are presented and discussed, showing preference to spherical indentation. The virtual J-integral approach with limit load analysis applied for estimating KJC in both indenters, incorporated stress triaxiality to account for pressure sensitivity and the hydrostatic pressure component in indentation testing. Results show that “e.t.d” 150 achieves fracture toughness and Brinell hardness values comparable to rail steels, particularly suitable for curved track sections where wear resistance and durability are critical. Fatigue analysis was also conducted for “e.t.d” 150, which confirms moderate-to-good resistance to rolling contact fatigue. These findings suggest that “e.t.d” 150 offers a reliable alternative for substituting conventional rail steels, with potential benefits for railway performance, safety, and maintenance cost reduction.
{"title":"Comprehensive mechanical evaluation of heat-treated AISI 4140 (ETD 150): fatigue behavior and novel indentation-based characterization of fracture toughness and hardness with relevance to rail steels","authors":"S.I. Okocha , M.T. Hendry , P.Y.B. Jar","doi":"10.1016/j.engfracmech.2026.111874","DOIUrl":"10.1016/j.engfracmech.2026.111874","url":null,"abstract":"<div><div>This study investigates the fracture toughness (K<sub>JC</sub>) and hardness of heat-treated, cold-drawn AISI 4140 alloy (“e.t.d” 150) alongside three representative rail steels (JP, EV, and CZ) to comparatively evaluate their mechanical performance. Importance is placed on “e.t.d” 150 to assess its potentiality as a viable alternative material for rail steel applications based on current insights to rail steel material recycling and substitution. Fracture toughness (K<sub>JC</sub>) was assessed using a chamfered cylindrical flat-end and spherical indenter based on a novel virtual J-integral approach that minimizes the plastic J-integral component based on Irwin’s elastic solution, while hardness was obtained using only spherical indentation. A comparison between the K<sub>JC</sub> outcomes of both indenters are presented and discussed, showing preference to spherical indentation. The virtual J-integral approach with limit load analysis applied for estimating K<sub>JC</sub> in both indenters, incorporated stress triaxiality to account for pressure sensitivity and the hydrostatic pressure component in indentation testing. Results show that “e.t.d” 150 achieves fracture toughness and Brinell hardness values comparable to rail steels, particularly suitable for curved track sections where wear resistance and durability are critical. Fatigue analysis was also conducted for “e.t.d” 150, which confirms moderate-to-good resistance to rolling contact fatigue. These findings suggest that “e.t.d” 150 offers a reliable alternative for substituting conventional rail steels, with potential benefits for railway performance, safety, and maintenance cost reduction.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111874"},"PeriodicalIF":5.3,"publicationDate":"2026-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146015860","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 : 2026-03-11Epub 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":"2026-03-11","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 : 2026-03-11Epub 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":"2026-03-11","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 : 2026-03-11Epub Date: 2026-01-20DOI: 10.1016/j.engfracmech.2026.111870
Boya Wu , Meichen Liu , Shangyi Dai , Junwan Li , Xiaochun Wu
This study reveals the cyclic softening mechanisms of AISI H13 steel under isothermal fatigue at 600°C through experimental characterization and dislocation density-based crystal plasticity finite element method. Experiments demonstrate that AISI H13 steel exhibits three distinct softening stages within the strain amplitude range of 0.5–1.1%, namely rapid softening, transitional softening, and steady softening. Microstructural analysis reveals that with increasing cycles, the softening phenomenon intensifies, with dislocation density continuously decreasing from rapid to slow rates, accompanied by the coarsening of carbides. Accordingly, a dislocation density-based crystal plasticity model coupling realistic martensitic lath block structures and damage evolution was developed to reveal cyclic softening mechanisms, achieving hysteresis loop predictions with errors below 5%. The model reveals the dominant role of statistically stored dislocations (SSD) in cyclic softening, with SSD density decreasing from 1.68 × 103 to 1.53 × 103 μm−2 within the first five cycles. This non-uniform recovery process generates stress concentration in high SSD regions and strain localization in low SSD regions, leading to strong coupling between damage and plastic strain that drives progressive steel degradation. Simulation results further demonstrate that increasing strain amplitude from 0.5% to 1.1% significantly enhances strain localization, with accumulated plastic strain in localized regions reaching 0.5 at the 5th cycle under high amplitude compared to merely 0.002 under low amplitude. This heterogeneity accelerates damage evolution, with damage variables exceeding 0.15 in critical regions at 1.1% strain amplitude while remaining zero at 0.5%, ultimately reducing fatigue life from 650 to 214 cycles and promoting secondary crack formation near primary crack tips.
{"title":"A dislocation density-based crystal plasticity finite element analysis of cyclic softening behavior of AISI H13 steel under isothermal fatigue","authors":"Boya Wu , Meichen Liu , Shangyi Dai , Junwan Li , Xiaochun Wu","doi":"10.1016/j.engfracmech.2026.111870","DOIUrl":"10.1016/j.engfracmech.2026.111870","url":null,"abstract":"<div><div>This study reveals the cyclic softening mechanisms of AISI H13 steel under isothermal fatigue at 600°C through experimental characterization and dislocation density-based crystal plasticity finite element method. Experiments demonstrate that AISI H13 steel exhibits three distinct softening stages within the strain amplitude range of 0.5–1.1%, namely rapid softening, transitional softening, and steady softening. Microstructural analysis reveals that with increasing cycles, the softening phenomenon intensifies, with dislocation density continuously decreasing from rapid to slow rates, accompanied by the coarsening of carbides. Accordingly, a dislocation density-based crystal plasticity model coupling realistic martensitic lath block structures and damage evolution was developed to reveal cyclic softening mechanisms, achieving hysteresis loop predictions with errors below 5%. The model reveals the dominant role of statistically stored dislocations (SSD) in cyclic softening, with SSD density decreasing from 1.68 × 10<sup>3</sup> to 1.53 × 10<sup>3</sup> μm<sup>−2</sup> within the first five cycles. This non-uniform recovery process generates stress concentration in high SSD regions and strain localization in low SSD regions, leading to strong coupling between damage and plastic strain that drives progressive steel degradation. Simulation results further demonstrate that increasing strain amplitude from 0.5% to 1.1% significantly enhances strain localization, with accumulated plastic strain in localized regions reaching 0.5 at the 5th cycle under high amplitude compared to merely 0.002 under low amplitude. This heterogeneity accelerates damage evolution, with damage variables exceeding 0.15 in critical regions at 1.1% strain amplitude while remaining zero at 0.5%, ultimately reducing fatigue life from 650 to 214 cycles and promoting secondary crack formation near primary crack tips.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"334 ","pages":"Article 111870"},"PeriodicalIF":5.3,"publicationDate":"2026-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026300","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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