Pub Date : 2025-02-19DOI: 10.1016/j.engfracmech.2025.110915
Zihui Wang , Zhixin Zhan , Qianyu Xia , Yanjun Zhang , Qiang Qin , Xuyang Li , Weiping Hu , Qingchun Meng , Hua Li
In the aerospace industry, many structural components in aircraft use open-hole structures, which are highly susceptible to fatigue failure, thus reducing the service life of the aircraft. Relevant studies both domestically and internationally have found that the fatigue life of open-hole structures in aircraft can be enhanced by employing the cold extrusion strengthening process. This paper investigates the impact of the hole cold-extrusion strengthening process on the fatigue life of open-hole structures. Using the framework of Continuum Damage Mechanics (CDM), a life prediction model is developed to estimate fatigue crack initiation. Model parameters are calibrated using experimental data. Numerical simulations are conducted to study the residual stress distribution resulting from varying levels of interference, and the trends are analyzed. The structure’s fatigue life is then predicted to identify the optimal interference level and understand the underlying mechanism of the cold-extrusion process. Additionally, a CDM-based machine learning model is developed, incorporating K-Nearest Neighbor (KNN), Gradient Boosting Regression Tree (GBRT), and Artificial Neural Network (ANN). Through comprehensive analysis, the optimal parameters for each algorithm are determined, enabling accurate fatigue life prediction while significantly reducing computation time.
{"title":"Fatigue life estimation of open-hole cold-extrusion strengthened structures using continuum damage mechanics and optimized machine learning models","authors":"Zihui Wang , Zhixin Zhan , Qianyu Xia , Yanjun Zhang , Qiang Qin , Xuyang Li , Weiping Hu , Qingchun Meng , Hua Li","doi":"10.1016/j.engfracmech.2025.110915","DOIUrl":"10.1016/j.engfracmech.2025.110915","url":null,"abstract":"<div><div>In the aerospace industry, many structural components in aircraft use open-hole structures, which are highly susceptible to fatigue failure, thus reducing the service life of the aircraft. Relevant studies both domestically and internationally have found that the fatigue life of open-hole structures in aircraft can be enhanced by employing the cold extrusion strengthening process. This paper investigates the impact of the hole cold-extrusion strengthening process on the fatigue life of open-hole structures. Using the framework of Continuum Damage Mechanics (CDM), a life prediction model is developed to estimate fatigue crack initiation. Model parameters are calibrated using experimental data. Numerical simulations are conducted to study the residual stress distribution resulting from varying levels of interference, and the trends are analyzed. The structure’s fatigue life is then predicted to identify the optimal interference level and understand the underlying mechanism of the cold-extrusion process. Additionally, a CDM-based machine learning model is developed, incorporating K-Nearest Neighbor (KNN), Gradient Boosting Regression Tree (GBRT), and Artificial Neural Network (ANN). Through comprehensive analysis, the optimal parameters for each algorithm are determined, enabling accurate fatigue life prediction while significantly reducing computation time.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110915"},"PeriodicalIF":4.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143452763","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 : 2025-02-19DOI: 10.1016/j.engfracmech.2025.110961
Tao Du , Zhimin Chen , Sidsel M. Johansen , Qiangqiang Zhang , Yuanzheng Yue , Morten M. Smedskjaer
The increasing demand for lighter and more durable glass materials relies on the development of stiffer, stronger, and tougher glasses. However, the design of new glasses with targeted properties is largely impeded due to the lack of composition-structure–property models. Here, we combine machine learning with high-throughput molecular dynamics simulations to predict the mechanical properties of 231 calcium aluminosilicate (CAS) glass compositions under varying preparation conditions. We demonstrate that prediction models based on neural networks can well capture both the elastic and fracture behaviors of CAS glasses. By interpretating the prediction model, we demonstrate that the Al2O3 content is the primary factor determining mechanical properties. Specifically, an increase in Al2O3 content leads to higher modulus, tensile strength, and toughness. The roles of preparation pressure and cooling rate are positively correlated with modulus and tensile strength, respectively. Structure analyses reveal that the fraction of oxygen triclusters is the key factor for controlling both the elastic and fracture behavior of the CAS glasses. Based on these findings, our work facilitates the rational design of new oxide glasses with targeted properties.
{"title":"Predicting stiffness and toughness of aluminosilicate glasses using an interpretable machine learning model","authors":"Tao Du , Zhimin Chen , Sidsel M. Johansen , Qiangqiang Zhang , Yuanzheng Yue , Morten M. Smedskjaer","doi":"10.1016/j.engfracmech.2025.110961","DOIUrl":"10.1016/j.engfracmech.2025.110961","url":null,"abstract":"<div><div>The increasing demand for lighter and more durable glass materials relies on the development of stiffer, stronger, and tougher glasses. However, the design of new glasses with targeted properties is largely impeded due to the lack of composition-structure–property models. Here, we combine machine learning with high-throughput molecular dynamics simulations to predict the mechanical properties of 231 calcium aluminosilicate (CAS) glass compositions under varying preparation conditions. We demonstrate that prediction models based on neural networks can well capture both the elastic and fracture behaviors of CAS glasses. By interpretating the prediction model, we demonstrate that the Al<sub>2</sub>O<sub>3</sub> content is the primary factor determining mechanical properties. Specifically, an increase in Al<sub>2</sub>O<sub>3</sub> content leads to higher modulus, tensile strength, and toughness. The roles of preparation pressure and cooling rate are positively correlated with modulus and tensile strength, respectively. Structure analyses reveal that the fraction of oxygen triclusters is the key factor for controlling both the elastic and fracture behavior of the CAS glasses. Based on these findings, our work facilitates the rational design of new oxide glasses with targeted properties.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110961"},"PeriodicalIF":4.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464919","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 : 2025-02-19DOI: 10.1016/j.engfracmech.2025.110963
Hugo C. Biscaia , Dilum Fernando , Jian-Guo Dai
Rehabilitation and retrofitting of existing structures using externally bonded fibre-reinforced polymers (FRP) have become increasingly popular. A common failure mode in such strengthened systems is the debonding of the FRP laminate from the substrate. To address this, various techniques have been developed to prevent or delay debonding failures. One such approach is the use of two adhesives with different elastic moduli, resulting in a mixed-adhesive joint. This technique is claimed to reduce stress concentrations at the plate ends, thereby delaying or preventing debonding failures. However, a detailed interfacial stress analysis, considering failure initiation and propagation within the bonded joint, has yet to be conducted to fully understand the effects of using a mixed adhesive. To address this gap, the present work proposes an analytical solution to describe the complete debonding process of FRP mixed-adhesive joints under mode II loading. This analytical solution is validated using the Finite Element Method (FEM), and several key parameters for mixed-adhesive joint design are identified. The results indicate that mixed-adhesive joints, compared to single-adhesive joints with a ductile adhesive, exhibit lower maximum load capacities. When the ductile adhesive is used as a loaded-end anchorage in the mixed-adhesive joint, the maximum load is higher than when it is used as an end anchorage. However, this configuration significantly reduces the ductility of the joint with the loaded-end anchorage.
{"title":"Prediction of the full debonding process of mixed-adhesive FRP-to-substrate joints through a new analytical method","authors":"Hugo C. Biscaia , Dilum Fernando , Jian-Guo Dai","doi":"10.1016/j.engfracmech.2025.110963","DOIUrl":"10.1016/j.engfracmech.2025.110963","url":null,"abstract":"<div><div>Rehabilitation and retrofitting of existing structures using externally bonded fibre-reinforced polymers (FRP) have become increasingly popular. A common failure mode in such strengthened systems is the debonding of the FRP laminate from the substrate. To address this, various techniques have been developed to prevent or delay debonding failures. One such approach is the use of two adhesives with different elastic moduli, resulting in a mixed-adhesive joint. This technique is claimed to reduce stress concentrations at the plate ends, thereby delaying or preventing debonding failures. However, a detailed interfacial stress analysis, considering failure initiation and propagation within the bonded joint, has yet to be conducted to fully understand the effects of using a mixed adhesive. To address this gap, the present work proposes an analytical solution to describe the complete debonding process of FRP mixed-adhesive joints under mode II loading. This analytical solution is validated using the Finite Element Method (FEM), and several key parameters for mixed-adhesive joint design are identified. The results indicate that mixed-adhesive joints, compared to single-adhesive joints with a ductile adhesive, exhibit lower maximum load capacities. When the ductile adhesive is used as a loaded-end anchorage in the mixed-adhesive joint, the maximum load is higher than when it is used as an end anchorage. However, this configuration significantly reduces the ductility of the joint with the loaded-end anchorage.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110963"},"PeriodicalIF":4.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474332","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 : 2025-02-18DOI: 10.1016/j.engfracmech.2025.110908
Feilong Li , Yue Su , Yunda Chen , Xiaoqiang Sun
This study presents the first extension of the high-fidelity time-domain spectral element method (TD-SEM) to develop a phase-field model for accurately and efficiently solving fracture problems in solids. TD-SEM combines the flexibility of the finite element method (FEM) with the precision of spectral methods. Compared to the standard finite element method, TD-SEM, which employs high-order shape functions within spectral elements, demonstrates superior accuracy and efficiency in solving continuum mechanics equations. The phase-field formulation captures complex crack behaviors, including initiation, propagation, and branching, without relying on predefined crack paths. Integrating TD-SEM with the phase-field method creates a hybrid technique that leverages the strengths of both frameworks, enabling precise predictions of intricate fracture patterns in solids. This study demonstrates that the phase-field TD-SEM exhibits superior performance compared to phase-field FEM and recently reported accelerated phase-field model in several aspects: it achieves a significantly faster convergence rate, maintains higher accuracy even with coarser meshes in the crack propagation region, and requires less computational effort. The phase-field TD-SEM is integrated into ABAQUS through the utilization of user-element (UEL) and user-material (UMAT) modules, with the weak coupled non-linear system being addressed by the in-built solver. The feasibility and effectiveness of the developed method are validated through several illustrative examples. This extension of high-fidelity TD-SEM for phase-field modeling shows promise for efficiently and accurately simulating crack propagation and phase-field evolution in fracture analysis.
{"title":"Extension of high-fidelity time-domain spectral element formulation for phase-field modeling of fracture: A static analysis","authors":"Feilong Li , Yue Su , Yunda Chen , Xiaoqiang Sun","doi":"10.1016/j.engfracmech.2025.110908","DOIUrl":"10.1016/j.engfracmech.2025.110908","url":null,"abstract":"<div><div>This study presents the first extension of the high-fidelity time-domain spectral element method (TD-SEM) to develop a phase-field model for accurately and efficiently solving fracture problems in solids. TD-SEM combines the flexibility of the finite element method (FEM) with the precision of spectral methods. Compared to the standard finite element method, TD-SEM, which employs high-order shape functions within spectral elements, demonstrates superior accuracy and efficiency in solving continuum mechanics equations. The phase-field formulation captures complex crack behaviors, including initiation, propagation, and branching, without relying on predefined crack paths. Integrating TD-SEM with the phase-field method creates a hybrid technique that leverages the strengths of both frameworks, enabling precise predictions of intricate fracture patterns in solids. This study demonstrates that the phase-field TD-SEM exhibits superior performance compared to phase-field FEM and recently reported accelerated phase-field model in several aspects: it achieves a significantly faster convergence rate, maintains higher accuracy even with coarser meshes in the crack propagation region, and requires less computational effort. The phase-field TD-SEM is integrated into ABAQUS through the utilization of user-element (UEL) and user-material (UMAT) modules, with the weak coupled non-linear system being addressed by the in-built solver. The feasibility and effectiveness of the developed method are validated through several illustrative examples. This extension of high-fidelity TD-SEM for phase-field modeling shows promise for efficiently and accurately simulating crack propagation and phase-field evolution in fracture analysis.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"317 ","pages":"Article 110908"},"PeriodicalIF":4.7,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143437825","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 : 2025-02-18DOI: 10.1016/j.engfracmech.2025.110959
Jinle Wang , Haoxu Ding , Bing Yang , Yongqi Duan , Xiaorui Wang , Tao Zhu , Shoune Xiao , Shizhong Zhao
Conduct a detailed study on the ductile fracture characteristics of A7N01S-T5 arc welding butt weld. Firstly, the weld area was divided through hardness testing, and it was found that the base metal area (BM) of A7N01S-T5 butt weld had the highest hardness, while the weld nugget area (WM) had the lowest hardness. Except for a weak hardness section (HAZ II) in the heat-affected zone, the hardness of the other areas (HAZ I) was close to that of the base metal. A series of fracture tests were conducted in different regions, and information on stress state parameters and equivalent fracture strain of different tests was obtained based on DIC technology and finite element reverse engineering method. On this basis, constitutive and fracture models of materials in different regions were constructed using the Swfit-Voce joint hardening criterion, DF2014 criteria, and DF2016 criteria. Finally, two uniaxial tensile loads and one three-point bending load were tested and simulated for the welded joints. The results indicate that the material model constructed by partitioning can effectively characterize the ductile fracture behavior of butt weld under different loads. For weld-enhanced joints, HAZ II has the lowest tensile strength; For ground flat joints, WM has the lowest tensile strength. Under the action of a three-point bending load, the ultimate bearing load and fracture displacement of the joint have a certain degree of discreteness due to the existence of quasi-brittle zones in the joint and the differences in defects at different positions of the weld.
{"title":"Study on fracture characteristics of A7N01S-T5 butt weld classified by hardness under different stress states","authors":"Jinle Wang , Haoxu Ding , Bing Yang , Yongqi Duan , Xiaorui Wang , Tao Zhu , Shoune Xiao , Shizhong Zhao","doi":"10.1016/j.engfracmech.2025.110959","DOIUrl":"10.1016/j.engfracmech.2025.110959","url":null,"abstract":"<div><div>Conduct a detailed study on the ductile fracture characteristics of A7N01S-T5 arc welding butt weld. Firstly, the weld area was divided through hardness testing, and it was found that the base metal area (BM) of A7N01S-T5 butt weld had the highest hardness, while the weld nugget area (WM) had the lowest hardness. Except for a weak hardness section (HAZ II) in the heat-affected zone, the hardness of the other areas (HAZ I) was close to that of the base metal. A series of fracture tests were conducted in different regions, and information on stress state parameters and equivalent fracture strain of different tests was obtained based on DIC technology and finite element reverse engineering method. On this basis, constitutive and fracture models of materials in different regions were constructed using the Swfit-Voce joint hardening criterion, DF2014 criteria, and DF2016 criteria. Finally, two uniaxial tensile loads and one three-point bending load were tested and simulated for the welded joints. The results indicate that the material model constructed by partitioning can effectively characterize the ductile fracture behavior of butt weld under different loads. For weld-enhanced joints, HAZ II has the lowest tensile strength; For ground flat joints, WM has the lowest tensile strength. Under the action of a three-point bending load, the ultimate bearing load and fracture displacement of the joint have a certain degree of discreteness due to the existence of quasi-brittle zones in the joint and the differences in defects at different positions of the weld.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110959"},"PeriodicalIF":4.7,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464918","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}
Insufficient knowledge of creep behavior in laser powder bed fusion (LPBF) Inconel 718 alloys hinders their prolonged high-temperature service, particularly concerning creep anisotropy. Utilizing the micro specimen advantages of the small punch creep test (SPCT), we performed a comprehensive analysis of creep anisotropy behavior, creep thermal activation energy, and fracture mechanisms. (1) During aging heat treatment, X-specimens and Z-specimens exhibit considerable creep anisotropy, which is markedly reduced with solution and aging heat treatment. (2) Creep thermal activation energy ranking is: X-specimen (618.33 kJ/mol) > rolled Inconel 718 (419.90 kJ/mol) > Z-specimen (263.65 kJ/mol), highlighting the creep resistance discrepancies between X-specimens, Z-specimens, and conventional rolled material. (3) Using the interrupted SPCT revealed that the fracture of X-specimens occurs via straight crack growth during the creep process, while Z-specimens fail owing to circumferential crack growth. This study’s key contributions lie in determining the creep thermal activation energy of LPBF Inconel 718 and elucidating its creep damage and fracture anisotropy. These findings address the knowledge gap regarding creep anisotropy in LPBF Inconel 718 and facilitate its wider engineering applications.
{"title":"The anisotropy of creep deformation, life, damage, activation energy, and fracture mode for LPBF Inconel 718 by small punch creep test","authors":"Qian Zhang , Mingxuan Gao , Jian Peng , Xinting Miao , Dongya Lu","doi":"10.1016/j.engfracmech.2025.110955","DOIUrl":"10.1016/j.engfracmech.2025.110955","url":null,"abstract":"<div><div>Insufficient knowledge of creep behavior in laser powder bed fusion (LPBF) Inconel 718 alloys hinders their prolonged high-temperature service, particularly concerning creep anisotropy. Utilizing the micro specimen advantages of the small punch creep test (SPCT), we performed a comprehensive analysis of creep anisotropy behavior, creep thermal activation energy, and fracture mechanisms. (1) During aging heat treatment, X-specimens and Z-specimens exhibit considerable creep anisotropy, which is markedly reduced with solution and aging heat treatment. (2) Creep thermal activation energy ranking is: X-specimen (618.33 kJ/mol) > rolled Inconel 718 (419.90 kJ/mol) > Z-specimen (263.65 kJ/mol), highlighting the creep resistance discrepancies between X-specimens, Z-specimens, and conventional rolled material. (3) Using the interrupted SPCT revealed that the fracture of X-specimens occurs via straight crack growth during the creep process, while Z-specimens fail owing to circumferential crack growth. This study’s key contributions lie in determining the creep thermal activation energy of LPBF Inconel 718 and elucidating its creep damage and fracture anisotropy. These findings address the knowledge gap regarding creep anisotropy in LPBF Inconel 718 and facilitate its wider engineering applications.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110955"},"PeriodicalIF":4.7,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143452762","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 : 2025-02-17DOI: 10.1016/j.engfracmech.2025.110954
Hui Wei , Baosheng Xu , Jue Li , Jianlong Zheng , Yunyao Liu , Runni Lu
Fatigue cracking severely impacts the structural integrity and service life of asphalt pavements. Temperature modifies asphalt mixture responses to traffic loading and fatigue resistance by altering binder properties. This study comprehensively characterized temperature-dependent fatigue behaviors through integrated experimentation and data analysis. Four-point bending tests were conducted on asphalt beams at 15℃, 20℃ and 25℃ combined with acoustic emission monitoring. A series of parameters, including the b-value and S-value, were extracted from the acoustic emission signals to characterize the damage stages. Cluster analysis classified dominant cracking modes associated with temperature. Digital image correlation validated crack propagation patterns. Results showed significant reductions in fatigue lives with 5℃ increments across the intermediate temperature range. Three distinctive damage stages were consistently identified irrespective of changing temperature. Clustering revealed tensile cracking comprised over 89% of events, increasingly favored by higher temperatures up to 25℃. Peak frequency shifts correlated rising temperatures with earlier micro–macro scale transitions. Digital image correlation supported faster crack growth kinetics at elevated temperatures. Key findings provided new perspectives on temperature accelerating microcrack initiation, linkage and macrocrack propagation governing failure.
{"title":"Effect of temperature on fatigue damage evolution of asphalt mixture based on cluster analysis and acoustic emission parameters","authors":"Hui Wei , Baosheng Xu , Jue Li , Jianlong Zheng , Yunyao Liu , Runni Lu","doi":"10.1016/j.engfracmech.2025.110954","DOIUrl":"10.1016/j.engfracmech.2025.110954","url":null,"abstract":"<div><div>Fatigue cracking severely impacts the structural integrity and service life of asphalt pavements. Temperature modifies asphalt mixture responses to traffic loading and fatigue resistance by altering binder properties. This study comprehensively characterized temperature-dependent fatigue behaviors through integrated experimentation and data analysis. Four-point bending tests were conducted on asphalt beams at 15℃, 20℃ and 25℃ combined with acoustic emission monitoring. A series of parameters, including the b-value and S-value, were extracted from the acoustic emission signals to characterize the damage stages. Cluster analysis classified dominant cracking modes associated with temperature. Digital image correlation validated crack propagation patterns. Results showed significant reductions in fatigue lives with 5℃ increments across the intermediate temperature range. Three distinctive damage stages were consistently identified irrespective of changing temperature. Clustering revealed tensile cracking comprised over 89% of events, increasingly favored by higher temperatures up to 25℃. Peak frequency shifts correlated rising temperatures with earlier micro–macro scale transitions. Digital image correlation supported faster crack growth kinetics at elevated temperatures. Key findings provided new perspectives on temperature accelerating microcrack initiation, linkage and macrocrack propagation governing failure.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"317 ","pages":"Article 110954"},"PeriodicalIF":4.7,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143437827","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 : 2025-02-17DOI: 10.1016/j.engfracmech.2025.110947
Xiankai Bao , Jianlong Qiao , Chaoyun Yu , Lingyu Wang , Baolong Tian , Yue Huang , Shunjia Huang
To investigate the dynamic expansion mechanism and behavior of coal rock cracks under impact loading, impact tests were conducted on side-open single-crack semi-circular plates using a large-diameter split Hopkinson pressure bar. The average crack propagation speed and the failure modes of the semi-circular coal samples were analyzed. Using ABAQUS software, the variation of dynamic fracture toughness of coal rock cracks was examined under different impact velocities and distances between pre-existing cracks and the central axis of coal rock specimens. The results indicate: (1) The greater the impact velocity, the more severe the final damage to the coal rock. The larger the distance between the pre-existing crack and the specimen’s central axis, the greater the crack deflection angle. When the pre-existing crack coincides with the central axis, the crack expands along the axis. When the crack deviates from the central axis, it initially deflects to the sides, then expands along the axis. I-II mixed-mode cracks are more susceptible to crack arrest compared to pure I-mode cracks. (2) The speed of crack propagation is relatively high during the initial stage of cracking, and then gradually decreases and fluctuates within a certain range. The maximum propagation speed of specimen H-0–5.2-A at an impact velocity of 5.2 m/s reached 842.11 m/s. The average propagation speed of the cracks increased with the rise in impact velocity. (3) When the pre-existing crack coincides with the central axis, both the dynamic initiation toughness and dynamic propagation toughness of the coal rock specimens increase with impact velocity. The dynamic propagation and arrest toughness of all specimens were lower than their dynamic initiation toughness. (4) At a constant impact velocity, as the distance between the pre-existing crack and the specimen’s central axis increases, the dynamic initiation, propagation, and arrest toughness of I-mode cracks remain unchanged, while those of II-mode cracks significantly increase, especially the propagation toughness. When the distance is x = 7 mm, the propagation toughness of II-mode cracks surpasses their initiation toughness.
{"title":"Study on the dynamic expansion mechanism and behavior of coal rock fractures under impact load","authors":"Xiankai Bao , Jianlong Qiao , Chaoyun Yu , Lingyu Wang , Baolong Tian , Yue Huang , Shunjia Huang","doi":"10.1016/j.engfracmech.2025.110947","DOIUrl":"10.1016/j.engfracmech.2025.110947","url":null,"abstract":"<div><div>To investigate the dynamic expansion mechanism and behavior of coal rock cracks under impact loading, impact tests were conducted on side-open single-crack semi-circular plates using a large-diameter split Hopkinson pressure bar. The average crack propagation speed and the failure modes of the semi-circular coal samples were analyzed. Using ABAQUS software, the variation of dynamic fracture toughness of coal rock cracks was examined under different impact velocities and distances between pre-existing cracks and the central axis of coal rock specimens. The results indicate: (1) The greater the impact velocity, the more severe the final damage to the coal rock. The larger the distance between the pre-existing crack and the specimen’s central axis, the greater the crack deflection angle. When the pre-existing crack coincides with the central axis, the crack expands along the axis. When the crack deviates from the central axis, it initially deflects to the sides, then expands along the axis. I-II mixed-mode cracks are more susceptible to crack arrest compared to pure I-mode cracks. (2) The speed of crack propagation is relatively high during the initial stage of cracking, and then gradually decreases and fluctuates within a certain range. The maximum propagation speed of specimen H-0–5.2-A at an impact velocity of 5.2 m/s reached 842.11 m/s. The average propagation speed of the cracks increased with the rise in impact velocity. (3) When the pre-existing crack coincides with the central axis, both the dynamic initiation toughness and dynamic propagation toughness of the coal rock specimens increase with impact velocity. The dynamic propagation and arrest toughness of all specimens were lower than their dynamic initiation toughness. (4) At a constant impact velocity, as the distance between the pre-existing crack and the specimen’s central axis increases, the dynamic initiation, propagation, and arrest toughness of I-mode cracks remain unchanged, while those of II-mode cracks significantly increase, especially the propagation toughness. When the distance is x = 7 mm, the propagation toughness of II-mode cracks surpasses their initiation toughness.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110947"},"PeriodicalIF":4.7,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143471476","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 : 2025-02-17DOI: 10.1016/j.engfracmech.2025.110930
Shirui Zhang , Quan Jiang , Shili Qiu , Shaojun Li , Yongyuan Kou , Dingping Xu
Strain bursting around deep underground excavations is a complex phenomenon. The velocity of the failed rock mass and the depth of the excavation damage zone (EDZ) are the important support design parameters that depend on the failure mechanism of strain bursting. The advanced numerical models have the potential to assist in the evaluation of rockbursts. In this study, based on the proposed Voronoi-based breakable block model (VBBM), which can accurately characterize the stress-induced tensile and shear fracture mechanisms of surrounding rock, a quantitative analysis method for determining the energy resulting from the hard rock rupture process is developed to analyze the excavation of cave 7 at the China Jinping Underground Laboratory Phase II (CJPL-II). The results indicate that most of the strain energy is transformed into fracture energy for new ruptured surfaces. The kinetic energy of the moving rock blocks accounts for approximately 16% of the strain energy released by the collapsed surrounding rock. The in-situ stress ratio (K) and rock mass strength significantly affect the depth and range of the EDZ. Compared with the semi-empirical energy demand for support system, the numerical results are more conservative.
{"title":"Assessment of strain bursting using a Voronoi-based breakable block model: A case study of 2400-m-deep tunnels","authors":"Shirui Zhang , Quan Jiang , Shili Qiu , Shaojun Li , Yongyuan Kou , Dingping Xu","doi":"10.1016/j.engfracmech.2025.110930","DOIUrl":"10.1016/j.engfracmech.2025.110930","url":null,"abstract":"<div><div>Strain bursting around deep underground excavations is a complex phenomenon. The velocity of the failed rock mass and the depth of the excavation damage zone (EDZ) are the important support design parameters that depend on the failure mechanism of strain bursting. The advanced numerical models have the potential to assist in the evaluation of rockbursts. In this study, based on the proposed Voronoi-based breakable block model (VBBM), which can accurately characterize the stress-induced tensile and shear fracture mechanisms of surrounding rock, a quantitative analysis method for determining the energy resulting from the hard rock rupture process is developed to analyze the excavation of cave 7 at the China Jinping Underground Laboratory Phase II (CJPL-II). The results indicate that most of the strain energy is transformed into fracture energy for new ruptured surfaces. The kinetic energy of the moving rock blocks accounts for approximately 16% of the strain energy released by the collapsed surrounding rock. The in-situ stress ratio (K) and rock mass strength significantly affect the depth and range of the EDZ. Compared with the semi-empirical energy demand for support system, the numerical results are more conservative.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110930"},"PeriodicalIF":4.7,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143446002","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 : 2025-02-16DOI: 10.1016/j.engfracmech.2025.110944
Youjun Ning , Cheng Zhao , Xinyang Lv , Lin Yao , Zheng Yang , Haofeng Chen
Discontinuous deformation analysis (DDA) is a representative numerical method for simulating the deformation and large displacement behaviors of discontinuous media like rock masses. For rock fracturing simulations, the previous sub-block element DDA fracturing modeling method (sub-block DDA method) only allows cracks to develop along artificial joints between sub-blocks, therefore showing high mesh dependency. In the present work, a new sub-block element splitting DDA fracturing modeling method (sub-block splitting DDA method) which allows the self-splitting of sub-blocks is developed. The new method determines the tensile and shear self-splitting of sub-block elements in crack initiation or propagation simulations based on the sub-block stress state. Its algorithm mainly involves the search of discontinuity loops, determination of crack tips, crack initiation and propagation criteria, and split and update of sub-block elements. Tensile failure tests of rectangular rock specimens with pre-existing cracks, radial compression splitting tests of an intact disc and rock discs with pre-existing cracks, and the Hopkinson spalling test of a rock rod are simulated. The simulation results are in good agreement with the corresponding experimental, theoretical, or other numerical simulation results. It is well demonstrated that the new method overcomes the limitations of previous DDA fracturing simulation methods which could only approximate crack paths by crack bands, and greatly reduces the mesh dependency effect. The seismic fracturing and failure of a jointed rock slope are also simulated. The characteristics of the failure process and failure mode of the slope are analyzed, and the seismic surface-oriented effect and elevation amplification effect are revealed. The new sub-block splitting DDA method provides a potential powerful numerical approach for rock mass mechanical behavior simulations involving deformation, fracturing and large displacements.
{"title":"Rock fracturing failure simulation via sub-block element splitting with discontinuous deformation analysis (DDA)","authors":"Youjun Ning , Cheng Zhao , Xinyang Lv , Lin Yao , Zheng Yang , Haofeng Chen","doi":"10.1016/j.engfracmech.2025.110944","DOIUrl":"10.1016/j.engfracmech.2025.110944","url":null,"abstract":"<div><div>Discontinuous deformation analysis (DDA) is a representative numerical method for simulating the deformation and large displacement behaviors of discontinuous media like rock masses. For rock fracturing simulations, the previous sub-block element DDA fracturing modeling method (sub-block DDA method) only allows cracks to develop along artificial joints between sub-blocks, therefore showing high mesh dependency. In the present work, a new sub-block element splitting DDA fracturing modeling method (sub-block splitting DDA method) which allows the self-splitting of sub-blocks is developed. The new method determines the tensile and shear self-splitting of sub-block elements in crack initiation or propagation simulations based on the sub-block stress state. Its algorithm mainly involves the search of discontinuity loops, determination of crack tips, crack initiation and propagation criteria, and split and update of sub-block elements. Tensile failure tests of rectangular rock specimens with pre-existing cracks, radial compression splitting tests of an intact disc and rock discs with pre-existing cracks, and the Hopkinson spalling test of a rock rod are simulated. The simulation results are in good agreement with the corresponding experimental, theoretical, or other numerical simulation results. It is well demonstrated that the new method overcomes the limitations of previous DDA fracturing simulation methods which could only approximate crack paths by crack bands, and greatly reduces the mesh dependency effect. The seismic fracturing and failure of a jointed rock slope are also simulated. The characteristics of the failure process and failure mode of the slope are analyzed, and the seismic surface-oriented effect and elevation amplification effect are revealed. The new sub-block splitting DDA method provides a potential powerful numerical approach for rock mass mechanical behavior simulations involving deformation, fracturing and large displacements.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110944"},"PeriodicalIF":4.7,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143452890","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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