Pub Date : 2025-01-09DOI: 10.1016/j.tafmec.2024.104842
Martha Kalina , Tom Schneider , Haim Waisman , Markus Kästner
Fatigue fracture is one of the main causes of failure in structures. However, the simulation of fatigue crack growth is computationally demanding due to the large number of load cycles involved. Metals in the low cycle fatigue range often show significant plastic zones at the crack tip, calling for elastic–plastic material models, which increase the computation time even further. In pursuit of a more efficient model, we propose a simplified phase-field model for ductile fatigue fracture, which indirectly accounts for plasticity within the fatigue damage accumulation. Additionally, a cycle-skipping approach is inherent to the concept, reducing computation time by up to several orders of magnitude. We show that the proposed model is in fact a direct simplification of a phase-field model with elastic–plastic material behavior.
We validate this simplified model in two ways: First, we show that it can reproduce the main characteristics of fatigue crack growth. Secondly, we compare it to a reference phase-field model with a conventional elastic–plastic material routine, nonlinear hardening and a fatigue variable based on the strain energy density. The comparison shows that for moderate load amplitudes, the simplified model approximates the stress state at the crack tip well. The same is true for size and shape of the plastic zone and the approximation of the crack driving force. The model’s limitations lie in the modeling of the stress redistribution due to plasticity. Both model variants are parametrized with experimentally determined values for elastic, plastic, fracture and fatigue properties of AA2024 T351 aluminum sheet material.
{"title":"Phase-field models for ductile fatigue fracture","authors":"Martha Kalina , Tom Schneider , Haim Waisman , Markus Kästner","doi":"10.1016/j.tafmec.2024.104842","DOIUrl":"10.1016/j.tafmec.2024.104842","url":null,"abstract":"<div><div>Fatigue fracture is one of the main causes of failure in structures. However, the simulation of fatigue crack growth is computationally demanding due to the large number of load cycles involved. Metals in the low cycle fatigue range often show significant plastic zones at the crack tip, calling for elastic–plastic material models, which increase the computation time even further. In pursuit of a more efficient model, we propose a simplified phase-field model for ductile fatigue fracture, which indirectly accounts for plasticity within the fatigue damage accumulation. Additionally, a cycle-skipping approach is inherent to the concept, reducing computation time by up to several orders of magnitude. We show that the proposed model is in fact a direct simplification of a phase-field model with elastic–plastic material behavior.</div><div>We validate this simplified model in two ways: First, we show that it can reproduce the main characteristics of fatigue crack growth. Secondly, we compare it to a reference phase-field model with a conventional elastic–plastic material routine, nonlinear hardening and a fatigue variable based on the strain energy density. The comparison shows that for moderate load amplitudes, the simplified model approximates the stress state at the crack tip well. The same is true for size and shape of the plastic zone and the approximation of the crack driving force. The model’s limitations lie in the modeling of the stress redistribution due to plasticity. Both model variants are parametrized with experimentally determined values for elastic, plastic, fracture and fatigue properties of AA2024 T351 aluminum sheet material.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104842"},"PeriodicalIF":5.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-09DOI: 10.1016/j.tafmec.2024.104837
Zhe Ji , Hong Su , Hongwei Li , Yaofeng Wang , Yue Gong , Taiming Zhao , Qichao Ge , Bo Yang
Pre-splitting blasting is extensively utilized in engineering tasks such as tunneling and underground chamber excavation. This study employs Digital Image Correlation (DIC) techniques and Dynamic Caustics Systems to examine the influence of pre-splitting crack, induced by pre-splitting blasting, on the dynamic fracture properties of blasting cracks into the remaining rock mass. The research findings reveal the critical role of pre-splitting crack in increasing damage to the blasted rock mass, impeding the propagation of blasting cracks towards the remaining rock mass, and promoting the initiation and propagation of primary cracks in remaining rock mass, particularly enhancing the cracks at the arch crown and the bottom of the arch abutment. The presence of pre-splitting crack significantly amplifies the strain field around the primary cracks, at the crack tips of these fractures, and near the pre-splitting crack, prolonging the duration of strain intensification. Moreover, pre-splitting crack increases the stress intensity factor at the tips of primary cracks, enabling more efficient energy accumulation before crack initiation. Consequently, the enhanced stress intensity factor at the tips of wing cracks following initiation fosters more rapid energy accumulation during crack propagation, thereby increasing the peak propagation velocity of the wing cracks. The outcomes of this study provide substantial theoretical and experimental support for the safe and efficient excavation of tunnels and galleries.
{"title":"Study on the influence of arched pre-splitting crack on cracks propagation under explosion load","authors":"Zhe Ji , Hong Su , Hongwei Li , Yaofeng Wang , Yue Gong , Taiming Zhao , Qichao Ge , Bo Yang","doi":"10.1016/j.tafmec.2024.104837","DOIUrl":"10.1016/j.tafmec.2024.104837","url":null,"abstract":"<div><div>Pre-splitting blasting is extensively utilized in engineering tasks such as tunneling and underground chamber excavation. This study employs Digital Image Correlation (DIC) techniques and Dynamic Caustics Systems to examine the influence of pre-splitting crack, induced by pre-splitting blasting, on the dynamic fracture properties of blasting cracks into the remaining rock mass. The research findings reveal the critical role of pre-splitting crack in increasing damage to the blasted rock mass, impeding the propagation of blasting cracks towards the remaining rock mass, and promoting the initiation and propagation of primary cracks in remaining rock mass, particularly enhancing the cracks at the arch crown and the bottom of the arch abutment. The presence of pre-splitting crack significantly amplifies the strain field around the primary cracks, at the crack tips of these fractures, and near the pre-splitting crack, prolonging the duration of strain intensification. Moreover, pre-splitting crack increases the stress intensity factor at the tips of primary cracks, enabling more efficient energy accumulation before crack initiation. Consequently, the enhanced stress intensity factor at the tips of wing cracks following initiation fosters more rapid energy accumulation during crack propagation, thereby increasing the peak propagation velocity of the wing cracks. The outcomes of this study provide substantial theoretical and experimental support for the safe and efficient excavation of tunnels and galleries.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104837"},"PeriodicalIF":5.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130678","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 : 2025-01-09DOI: 10.1016/j.tafmec.2025.104846
Rongcheng Wang , Huan Sheng Lai , Sixiong Zeng , Yuntao Zhong , Xueliang Sun , Jinquan Guo , Quan Wen
Determination of tensile properties is essential for the design and strength assessment of structures. In this study, a modified small punch test (SPT), known as the single-stress small punch test (SS-SPT), was proposed to investigate the tensile properties of five ductile homogeneous materials, namely P91, Q245R, 316SS, 1045 steel, and 2024Al. The SS-SPT specimen was subjected to a single stress state when subjected to a punch force, similar to that of a uniaxial tensile test (UTT) specimen. Additionally, UTT and standard SPT were carried out to investigate the tensile properties of these materials. The thickness of failed standard SPT and SS-SPT specimens was measured using a scanning electron microscope (SEM) and the equivalent fracture strain was calculated. Correlation relationships between each type of SPT and UTT results were established. Experimental results indicated that both the SS-SPT and standard SPT demonstrated comparable accuracy in determining yield stress, ultimate tensile stress, and tensile elongation. However, the SS-SPT exhibited greater accuracy than the standard SPT in determining fracture strain due to direct measurement of the thinnest thickness from the fracture in failed SS-SPT specimens.
{"title":"A modified small punch test to investigate tensile properties","authors":"Rongcheng Wang , Huan Sheng Lai , Sixiong Zeng , Yuntao Zhong , Xueliang Sun , Jinquan Guo , Quan Wen","doi":"10.1016/j.tafmec.2025.104846","DOIUrl":"10.1016/j.tafmec.2025.104846","url":null,"abstract":"<div><div>Determination of tensile properties is essential for the design and strength assessment of structures. In this study, a modified small punch test (SPT), known as the single-stress small punch test (SS-SPT), was proposed to investigate the tensile properties of five ductile homogeneous materials, namely P91, Q245R, 316SS, 1045 steel, and 2024Al. The SS-SPT specimen was subjected to a single stress state when subjected to a punch force, similar to that of a uniaxial tensile test (UTT) specimen. Additionally, UTT and standard SPT were carried out to investigate the tensile properties of these materials. The thickness of failed standard SPT and SS-SPT specimens was measured using a scanning electron microscope (SEM) and the equivalent fracture strain was calculated. Correlation relationships between each type of SPT and UTT results were established. Experimental results indicated that both the SS-SPT and standard SPT demonstrated comparable accuracy in determining yield stress, ultimate tensile stress, and tensile elongation. However, the SS-SPT exhibited greater accuracy than the standard SPT in determining fracture strain due to direct measurement of the thinnest thickness from the fracture in failed SS-SPT specimens.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104846"},"PeriodicalIF":5.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130675","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 : 2025-01-08DOI: 10.1016/j.tafmec.2024.104806
Ji Wan, Wenzhong Qu, Xihua Chu
In this article, we develop a peridynamic model for the micropolar elastic solids called operator-derived micropolar peridynamics (OMPD). Two types of OMPD models, namely the OMPD model-I based on the peridynamic differential operator and model-II based on the peridynamic operator method with second-order vector derivative, are obtained. By using the first-order Taylor series expansion (TSE), model-I can recover the previously proposed non-ordinary state-based micropolar peridynamics. However, the OMPD Model-I of any order TSE still suffers from zero-energy mode instability, while the proposed OMPD model-II is free of zero-energy mode and thus produces the correct micropolar elasticity response. The OMPD model-II produces an ordinary-like state-based micropolar peridynamic model with a symmetric horizon, which degenerates to the ordinary state-based peridynamics by vanishing the Cosserat shear modulus and micro-rotations. Furthermore, a novel bond-based micropolar peridynamics is derived with some moduli restrictions. Such bond-based micropolar peridynamics considers shear deformability and average micro-rotational effect in the shear bonds, and inherits the couple force generated by shear bond force from the OMPD model-II, which is essential to be consistent with Eringen’s micropolar elastic theory. We show that the novel bond-based micropolar peridynamics relaxes Poisson’s ratio fixation to a rigorous range from -1 to 1/4. Several numerical examples are provided to validate the models’ capacity in modeling micropolar solids and the crack propagation behavior.
{"title":"Operator-derived micropolar peridynamics","authors":"Ji Wan, Wenzhong Qu, Xihua Chu","doi":"10.1016/j.tafmec.2024.104806","DOIUrl":"10.1016/j.tafmec.2024.104806","url":null,"abstract":"<div><div>In this article, we develop a peridynamic model for the micropolar elastic solids called operator-derived micropolar peridynamics (OMPD). Two types of OMPD models, namely the OMPD model-I based on the peridynamic differential operator and model-II based on the peridynamic operator method with second-order vector derivative, are obtained. By using the first-order Taylor series expansion (TSE), model-I can recover the previously proposed non-ordinary state-based micropolar peridynamics. However, the OMPD Model-I of any order TSE still suffers from zero-energy mode instability, while the proposed OMPD model-II is free of zero-energy mode and thus produces the correct micropolar elasticity response. The OMPD model-II produces an ordinary-like state-based micropolar peridynamic model with a symmetric horizon, which degenerates to the ordinary state-based peridynamics by vanishing the Cosserat shear modulus and micro-rotations. Furthermore, a novel bond-based micropolar peridynamics is derived with some moduli restrictions. Such bond-based micropolar peridynamics considers shear deformability and average micro-rotational effect in the shear bonds, and inherits the couple force generated by shear bond force from the OMPD model-II, which is essential to be consistent with Eringen’s micropolar elastic theory. We show that the novel bond-based micropolar peridynamics relaxes Poisson’s ratio fixation to a rigorous range from -1 to 1/4. Several numerical examples are provided to validate the models’ capacity in modeling micropolar solids and the crack propagation behavior.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104806"},"PeriodicalIF":5.0,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130680","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 : 2025-01-08DOI: 10.1016/j.tafmec.2025.104845
Zeyue Wang , Hang Lin , Xinglong Feng , Chaoyi Yang , Ke Ou , Yifan Chen
In underground coal gasification (UCG) and enhanced geothermal systems (EGS), deep rock masses are simultaneously subjected to in-situ stress and high temperatures. Furthermore, joint defects are commonly distributed within the working tunnels of UCG and the geothermal drillings. Hence, it is essential to investigate the fracture characteristics of rock with hole-joint combined flaw under heat treatment and monotonic loading conditions. X-ray diffraction and thermogravimetric tests showed free and structural water separation causes thermal damage in sandstone. The evaporation of free water reduces the distance between crystals and strengthens sandstone. The separation of structural water generates a large number of transgranular cracks, which greatly reduces the sandstone strength. This research performed uniaxial compression experiments to investigate the mechanical characteristics, failure behaviours, energy dissipation, damage constitutive relations, and precursory features of instability in heat-treated sandstone (25 °C to 800 °C) with hole-joint defect under monotonic loading conditions. The acoustic emission (AE) signals and digital image correlation (DIC) data were simultaneously recorded during the tests. The research outcomes reveal that with climbing temperatures, the peak strength of sandstone first rises and then drops, turning at 200 °C. The stiffness of the specimens gradually weakens with rising temperatures, while their ductility gradually enhances. The failure behaviours of sandstone subjected are divided into two modes: wing crack-dominated and anti-wing crack-dominated. As the temperature rises, the failure mechanism of the specimens tends to transition from anti-wing crack-dominated to wing crack-dominated. However, the heat treatment merely enhances the ratio of shear cracks without altering the tensile-dominated failure mode. It is found that rocks subjected to higher temperatures exhibit greater dissipated energy, higher degrees of fragmentation, and lower levels of damage severity λmax. The damage constitutive model derived from energy evolution divides the damage cycle into four steps: a slow growth period, a silent period, a stepped growth period, and a rapid growth period. Finally, based on the critical slowing down (CSD) theory, the variance and autocorrelation coefficient curves of AE parameters were obtained. It was found that the gap between the critical point of the variance of AE parameters and the breaking point increased with rising temperature.
{"title":"Fracture characteristics and damage mechanisms of heat-treated sandstone with combined hole-joint flaws under uniaxial compression","authors":"Zeyue Wang , Hang Lin , Xinglong Feng , Chaoyi Yang , Ke Ou , Yifan Chen","doi":"10.1016/j.tafmec.2025.104845","DOIUrl":"10.1016/j.tafmec.2025.104845","url":null,"abstract":"<div><div>In underground coal gasification (UCG) and enhanced geothermal systems (EGS), deep rock masses are simultaneously subjected to in-situ stress and high temperatures. Furthermore, joint defects are commonly distributed within the working tunnels of UCG and the geothermal drillings. Hence, it is essential to investigate the fracture characteristics of rock with hole-joint combined flaw under heat treatment and monotonic loading conditions. X-ray diffraction and thermogravimetric tests showed free and structural water separation causes thermal damage in sandstone. The evaporation of free water reduces the distance between crystals and strengthens sandstone. The separation of structural water generates a large number of transgranular cracks, which greatly reduces the sandstone strength. This research performed uniaxial compression experiments to investigate the mechanical characteristics, failure behaviours, energy dissipation, damage constitutive relations, and precursory features of instability in heat-treated sandstone (25 °C to 800 °C) with hole-joint defect under monotonic loading conditions. The acoustic emission (AE) signals and digital image correlation (DIC) data were simultaneously recorded during the tests. The research outcomes reveal that with climbing temperatures, the peak strength of sandstone first rises and then drops, turning at 200 °C. The stiffness of the specimens gradually weakens with rising temperatures, while their ductility gradually enhances. The failure behaviours of sandstone subjected are divided into two modes: wing crack-dominated and anti-wing crack-dominated. As the temperature rises, the failure mechanism of the specimens tends to transition from anti-wing crack-dominated to wing crack-dominated. However, the heat treatment merely enhances the ratio of shear cracks without altering the tensile-dominated failure mode. It is found that rocks subjected to higher temperatures exhibit greater dissipated energy, higher degrees of fragmentation, and lower levels of damage severity <em>λ</em><sub>max</sub>. The damage constitutive model derived from energy evolution divides the damage cycle into four steps: a slow growth period, a silent period, a stepped growth period, and a rapid growth period. Finally, based on the critical slowing down (CSD) theory, the variance and autocorrelation coefficient curves of AE parameters were obtained. It was found that the gap between the critical point of the variance of AE parameters and the breaking point increased with rising temperature.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104845"},"PeriodicalIF":5.0,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130679","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 : 2025-01-06DOI: 10.1016/j.tafmec.2025.104844
Xiangxiang Zhang , Shaoyan Wu , Chengyu Liu , Shanjie Su
Liquid nitrogen (LN2) fracturing has been proposed to be used in unconventional gas engineering, including shale reservoirs. However, the effect of LN2 cooling on the fracture behaviors of bedding shale has not been well studied. In this study, three-point bending tests were conducted on shale samples at room temperature and under LN2 cooling condition, respectively. Different bedding angles were considered in these tests. The phenomenon of acoustic emission was monitored during the fracture initiation and propagation of bedding shale. The results showed that the tensile strength, fracture toughness, bending elastic modulus and fracture energy decreased with the increase of bedding angle under the same temperature condition, but the bedding angle has no significant effect on energy storage ratio and speed. There was a linear relationship between the tensile strength and fracture toughness of bedding shale. The crack initiation was inconsistent with the loading reference line except in 90° bedding shale, and then turned to the direction parallel to the loading reference line, resulting in various fracture morphology of bedding shale. The acoustic emission signals were mainly concentrated in the failure stage because of the severe brittleness of bedding shale. Under LN2 cooling condition, the tensile strength, fracture toughness, bending elastic modulus, energy storage ratio, fracture energy and AE cumulative ringing counts of bedding shale with the same bedding angle significantly increased, but the energy storage speed decreased. The crack length along bedding direction was longer and the crack inflection point was clearer than those of bedding shale at room temperature.
{"title":"An experimental investigation into the effect of liquid nitrogen cooling on fracture behaviors of bedding shale","authors":"Xiangxiang Zhang , Shaoyan Wu , Chengyu Liu , Shanjie Su","doi":"10.1016/j.tafmec.2025.104844","DOIUrl":"10.1016/j.tafmec.2025.104844","url":null,"abstract":"<div><div>Liquid nitrogen (LN<sub>2</sub>) fracturing has been proposed to be used in unconventional gas engineering, including shale reservoirs. However, the effect of LN<sub>2</sub> cooling on the fracture behaviors of bedding shale has not been well studied. In this study, three-point bending tests were conducted on shale samples at room temperature and under LN<sub>2</sub> cooling condition, respectively. Different bedding angles were considered in these tests. The phenomenon of acoustic emission was monitored during the fracture initiation and propagation of bedding shale. The results showed that the tensile strength, fracture toughness, bending elastic modulus and fracture energy decreased with the increase of bedding angle under the same temperature condition, but the bedding angle has no significant effect on energy storage ratio and speed. There was a linear relationship between the tensile strength and fracture toughness of bedding shale. The crack initiation was inconsistent with the loading reference line except in 90° bedding shale, and then turned to the direction parallel to the loading reference line, resulting in various fracture morphology of bedding shale. The acoustic emission signals were mainly concentrated in the failure stage because of the severe brittleness of bedding shale. Under LN<sub>2</sub> cooling condition, the tensile strength, fracture toughness, bending elastic modulus, energy storage ratio, fracture energy and AE cumulative ringing counts of bedding shale with the same bedding angle significantly increased, but the energy storage speed decreased. The crack length along bedding direction was longer and the crack inflection point was clearer than those of bedding shale at room temperature.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104844"},"PeriodicalIF":5.0,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130677","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 : 2025-01-03DOI: 10.1016/j.tafmec.2025.104843
Fei Wang , Zhi Liang He , Jian Hui Deng , Fei Chen , Els Verstrynge
The rupture behavior of rocks in water environments is influenced by complex rock-water interactions, with stress corrosion recognized as a significant factor. However, the effect of stress corrosion on rock rupture is often masked by concurrent rock-water interaction mechanisms, complicating its isolated analysis. In this study, fused quartz glass samples were used to eliminate extraneous factors, enabling a dedicated investigation of the stress corrosion-induced rupture under controlled fracture modes and water conditions. Semi-circular bending tests in a water-based environment were conducted, with fracture processes monitored using the acoustic emission (AE) technique. Loading curves, rupture paths, and surface morphologies were analyzed to reveal macroscale fracture features. AE parameter analysis, source localization, and moment tensor inversion were employed to investigate spatiotemporal damage evolution at the mesoscale. The stress corrosion-induced failure exhibits interesting softening fracture behavior at both the mesoscale and macroscale. At the macroscale, softening deformation is induced by stress corrosion, with energy release at the crack tip occurring gently. At the mesoscale, meso-crack proliferation can be triggered by stress corrosion, leading to a cross-scale damage evolution process. The damage process exhibits distinct instability characteristics at 50–80 % load levels under mode I fracture, whereas it remains relatively stable under mode II fracture. As peak stress approaches, the proliferation of mesoscale fractures forms an irreversible crack network that alters the local mesostructure, governing failure behavior and facilitating macroscale softening rupture. It is found that the flowing water and tensile fracture mode stimulate corrosion and intensify degradation, which deserves heightened concern in engineering.
{"title":"Investigating stress corrosion-induced rupture behavior using the acoustic emission technique","authors":"Fei Wang , Zhi Liang He , Jian Hui Deng , Fei Chen , Els Verstrynge","doi":"10.1016/j.tafmec.2025.104843","DOIUrl":"10.1016/j.tafmec.2025.104843","url":null,"abstract":"<div><div>The rupture behavior of rocks in water environments is influenced by complex rock-water interactions, with stress corrosion recognized as a significant factor. However, the effect of stress corrosion on rock rupture is often masked by concurrent rock-water interaction mechanisms, complicating its isolated analysis. In this study, fused quartz glass samples were used to eliminate extraneous factors, enabling a dedicated investigation of the stress corrosion-induced rupture under controlled fracture modes and water conditions. Semi-circular bending tests in a water-based environment were conducted, with fracture processes monitored using the acoustic emission (AE) technique. Loading curves, rupture paths, and surface morphologies were analyzed to reveal macroscale fracture features. AE parameter analysis, source localization, and moment tensor inversion were employed to investigate spatiotemporal damage evolution at the mesoscale. The stress corrosion-induced failure exhibits interesting softening fracture behavior at both the mesoscale and macroscale. At the macroscale, softening deformation is induced by stress corrosion, with energy release at the crack tip occurring gently. At the mesoscale, <em>meso</em>-crack proliferation can be triggered by stress corrosion, leading to a cross-scale damage evolution process. The damage process exhibits distinct instability characteristics at 50–80 % load levels under mode I fracture, whereas it remains relatively stable under mode II fracture. As peak stress approaches, the proliferation of mesoscale fractures forms an irreversible crack network that alters the local mesostructure, governing failure behavior and facilitating macroscale softening rupture. It is found that the flowing water and tensile fracture mode stimulate corrosion and intensify degradation, which deserves heightened concern in engineering.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104843"},"PeriodicalIF":5.0,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130682","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 : 2025-01-02DOI: 10.1016/j.tafmec.2024.104839
Gerardo E. Oleaga , Brigit Mittelman , Zohar Yosibash
A parent flat crack under pure mode III kinks in subsequent crack nucleation. It fragments leaving a complex crack nucleation pattern of facets on the fracture surface. However, the energy release rate (ERR), erroneously predicts a crack nucleation path along the original flat surface (similarly to mode I loading) (Mittelman and Yosibash, 2015), contradicting experimental observations.
We consider here a surrogate simplified problem for a possible reconciliation of the ERR prediction leading to the fragmented surface: the Laplace equation in a circular 2D domain with a crack. This problem represents the cross-section of a 3D circular bar with a longitudinal crack under mode III. An asymptotic analysis demonstrated a maximum ERR resulting from a small crack segment that kinks from the tip of a parent crack when the first non-singular small term in mode III loading is non-zero (Oleaga, 2004, 2006).
Here we present the asymptotic mathematical analysis and investigate it further by a finite element analysis. We thereafter generalize the mathematical analysis to a small crack nucleating at a V-notched tip and interpret the outcome concerning the elasticity system under pure mode III loading.
{"title":"Insights on kinked cracks under mode III","authors":"Gerardo E. Oleaga , Brigit Mittelman , Zohar Yosibash","doi":"10.1016/j.tafmec.2024.104839","DOIUrl":"10.1016/j.tafmec.2024.104839","url":null,"abstract":"<div><div>A parent flat crack under pure mode III kinks in subsequent crack nucleation. It fragments leaving a complex crack nucleation pattern of facets on the fracture surface. However, the energy release rate (ERR), erroneously predicts a crack nucleation path along the original flat surface (similarly to mode I loading) (Mittelman and Yosibash, 2015), contradicting experimental observations.</div><div>We consider here a surrogate simplified problem for a possible reconciliation of the ERR prediction leading to the fragmented surface: the Laplace equation in a circular 2D domain with a crack. This problem represents the cross-section of a 3D circular bar with a <em>longitudinal crack</em> under mode III. An asymptotic analysis demonstrated a maximum ERR resulting from a small crack segment that kinks from the tip of a parent crack when the first non-singular small term in mode III loading is non-zero (Oleaga, 2004, 2006).</div><div>Here we present the asymptotic mathematical analysis and investigate it further by a finite element analysis. We thereafter generalize the mathematical analysis to a small crack nucleating at a V-notched tip and interpret the outcome concerning the elasticity system under pure mode III loading.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104839"},"PeriodicalIF":5.0,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130684","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 : 2024-12-28DOI: 10.1016/j.tafmec.2024.104832
Zesheng Zang , Zhonghui Li , Yue Niu , Shan Yin , Xiangguo Kong
The stability of underground construction is seriously compromised by the joints, faults, and other defects existing in the natural coal mass. Understanding the energy evolution and damage characteristics of its fracture process is of great significance for the prediction and early warning of deep coal-rock dynamic disasters. In this paper, the uniaxial compression experiments are conducted on defective coals with simultaneous testing of acoustic emission (AE) and electric potential (EP) from specimen rupture. The energy evolution characteristics of the defective coals’ damage destruction process were investigated. The evolution laws of AE and EP were analyzed. The fracture characteristics and damage evolution characteristics of the specimens were revealed. The damage constitutive model based on the coupled AE and EP characterization was established. The findings indicate that: (1) prefabricated flaws have a significant weakening effect on the specimens. As the flaw inclination increases, the lesser the weakening effect on the energy storage capacity of the specimens. Both EP and AE responses effectively reflect the energy dissipation of the specimen. (2) Both the βte of EP and the βta of AE exhibit significant precursor anomalies before severe damage occurs to the specimen. Employing a monitoring method combined with βte and βta enables precise early warnings of coal instability processes. (3) According to the Lemaitre strain equivalence principle, a damage constitutive model of defective coal based on AE and EP coupling characterization is established. The model can effectively calculate the stress state of the specimen. These research findings offer crucial theoretical guidance for enhancing the stability of underground engineering and ensuring safe coal mine operations.
{"title":"Energy evolution and constitutive model of flawed coal failure based on acoustic emission and electric potential characterisation","authors":"Zesheng Zang , Zhonghui Li , Yue Niu , Shan Yin , Xiangguo Kong","doi":"10.1016/j.tafmec.2024.104832","DOIUrl":"10.1016/j.tafmec.2024.104832","url":null,"abstract":"<div><div>The stability of underground construction is seriously compromised by the joints, faults, and other defects existing in the natural coal mass. Understanding the energy evolution and damage characteristics of its fracture process is of great significance for the prediction and early warning of deep coal-rock dynamic disasters. In this paper, the uniaxial compression experiments are conducted on defective coals with simultaneous testing of acoustic emission (AE) and electric potential (EP) from specimen rupture. The energy evolution characteristics of the defective coals’ damage destruction process were investigated. The evolution laws of AE and EP were analyzed. The fracture characteristics and damage evolution characteristics of the specimens were revealed. The damage constitutive model based on the coupled AE and EP characterization was established. The findings indicate that: (1) prefabricated flaws have a significant weakening effect on the specimens. As the flaw inclination increases, the lesser the weakening effect on the energy storage capacity of the specimens. Both EP and AE responses effectively reflect the energy dissipation of the specimen. (2) Both the <em>β<sub>te</sub></em> of EP and the <em>β<sub>ta</sub></em> of AE exhibit significant precursor anomalies before severe damage occurs to the specimen. Employing a monitoring method combined with <em>β<sub>te</sub></em> and <em>β<sub>ta</sub></em> enables precise early warnings of coal instability processes. (3) According to the Lemaitre strain equivalence principle, a damage constitutive model of defective coal based on AE and EP coupling characterization is established. The model can effectively calculate the stress state of the specimen. These research findings offer crucial theoretical guidance for enhancing the stability of underground engineering and ensuring safe coal mine operations.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104832"},"PeriodicalIF":5.0,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130456","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 : 2024-12-28DOI: 10.1016/j.tafmec.2024.104841
Yibo Zhang , Hetong Liu , Mingda Han , Weixu Zhang
In high-temperature environments, oxygen may accelerates the initiation and propagation of fatigue cracks. It significantly affects the performance of structures and restricts their service life. Therefore, it is necessary to study the mechanisms by which oxygen diffusion and oxidation affect fatigue crack propagation at high temperatures. To date, although various mechanisms and models for the influence of oxygen on crack propagation have been proposed, a comprehensive review of the subject is still not available. This paper aims to provide an overview of the topic to help readers understand the field. At first, the paper discusses the influencing factors and mechanisms of oxygen-accelerated crack propagation. Secondly, the relevant models are discussed, including mechanism model, the oxygen-assisted fracture model, the crack growth rate model, and the life prediction model. Thirdly, the paper suggests the limitations and the improvement direction of the models.
{"title":"Mechanisms and models of oxygen-assisted fatigue crack propagation at high temperature: A review","authors":"Yibo Zhang , Hetong Liu , Mingda Han , Weixu Zhang","doi":"10.1016/j.tafmec.2024.104841","DOIUrl":"10.1016/j.tafmec.2024.104841","url":null,"abstract":"<div><div>In high-temperature environments, oxygen may accelerates the initiation and propagation of fatigue cracks. It significantly affects the performance of structures and restricts their service life. Therefore, it is necessary to study the mechanisms by which oxygen diffusion and oxidation affect fatigue crack propagation at high temperatures. To date, although various mechanisms and models for the influence of oxygen on crack propagation have been proposed, a comprehensive review of the subject is still not available. This paper aims to provide an overview of the topic to help readers understand the field. At first, the paper discusses the influencing factors and mechanisms of oxygen-accelerated crack propagation. Secondly, the relevant models are discussed, including mechanism model, the oxygen-assisted fracture model, the crack growth rate model, and the life prediction model. Thirdly, the paper suggests the limitations and the improvement direction of the models.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104841"},"PeriodicalIF":5.0,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130569","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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