Engineering Fracture Mechanics最新文献_第3页

A crack-bridging model considering microstructural randomness in biological composite materials

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110687

Yi Yan , Xin-Yu Li , Cheng-Yuan Zhang , Xiao-Wen Lei , Zi-Chen Deng

The macroscopic mechanical properties of biological composite materials, such as strength and fracture toughness, are determined by both their constituents and microstructure. Conventional researches often assume that these properties can be modeled using representative volume elements that features microstructural periodicity. However, in reality, such periodicity is absent, and the mechanical and geometric properties of the constituents exhibit spatial randomness, profoundly affecting the material’s macroscopic behavior. In this study, we modify the classic crack-bridging model to account for microstructural randomness. Using the brick–mortar microstructure of nacre as an example, we investigate how microstructural randomness influences macroscopic fracture toughness and the mechanical properties of the crack-bridging zone. The results demonstrate that microstructural randomness weakens macroscopic fracture toughness, in line with the classic weakest-link principle. However, the randomness in macroscopic fracture toughness is significantly reduced compared to microstructural randomness, suggesting that the weakening effect induced by microstructural randomness is suppressed. Further analysis reveals that as the length of platelets increases, the weakening effect of microstructural randomness becomes less significant. This indicates that the microstructural stress transfer mechanism is responsible for suppressing the negative impact of microstructural randomness. Beyond the conventional strengthening and toughening effects, our results highlight a new advantage of well-designed microstructures in biological materials, offering deeper insights into how microscopic heterogeneity influences the macroscopic fracture toughness of these materials.

{"title":"A crack-bridging model considering microstructural randomness in biological composite materials","authors":"Yi Yan , Xin-Yu Li , Cheng-Yuan Zhang , Xiao-Wen Lei , Zi-Chen Deng","doi":"10.1016/j.engfracmech.2024.110687","DOIUrl":"10.1016/j.engfracmech.2024.110687","url":null,"abstract":"<div><div>The macroscopic mechanical properties of biological composite materials, such as strength and fracture toughness, are determined by both their constituents and microstructure. Conventional researches often assume that these properties can be modeled using representative volume elements that features microstructural periodicity. However, in reality, such periodicity is absent, and the mechanical and geometric properties of the constituents exhibit spatial randomness, profoundly affecting the material’s macroscopic behavior. In this study, we modify the classic crack-bridging model to account for microstructural randomness. Using the brick–mortar microstructure of nacre as an example, we investigate how microstructural randomness influences macroscopic fracture toughness and the mechanical properties of the crack-bridging zone. The results demonstrate that microstructural randomness weakens macroscopic fracture toughness, in line with the classic weakest-link principle. However, the randomness in macroscopic fracture toughness is significantly reduced compared to microstructural randomness, suggesting that the weakening effect induced by microstructural randomness is suppressed. Further analysis reveals that as the length of platelets increases, the weakening effect of microstructural randomness becomes less significant. This indicates that the microstructural stress transfer mechanism is responsible for suppressing the negative impact of microstructural randomness. Beyond the conventional strengthening and toughening effects, our results highlight a new advantage of well-designed microstructures in biological materials, offering deeper insights into how microscopic heterogeneity influences the macroscopic fracture toughness of these materials.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110687"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165312","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}

引用次数: 0

An analytical model for predicting the shear fracture behavior of discontinuities with multi-scale asperities incorporating the damage element method

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110706

Chaoyang Zhang, Chong Jiang, Li Pang

Asperities within discontinuities play a critical role in contributing to shear resistance. However, their influence on the shear fracture behavior of discontinuities is constrained by size effects. Revealing and predicting the fracture process of discontinuities with multi-scale asperities is crucial for guiding engineering stability assessment. In this study, PFC^2D was employed to simulate the microscopic fracture process of discontinuities with multi-scale asperities under shear loading conditions. The simulation revealed that first-order asperities predominantly experience wear failure, whereas second-order asperities primarily undergo shear failure. Based on these findings, the damage evolution equation for the microscopic elements of first-order asperities was formulated using classical wear theory, while the equation for second-order asperities employed Weibull distribution statistical theory. Consequently, an analytical model was developed that considers the influence of multi-scale asperities on the shear behavior of discontinuities incorporating the damage element method. Subsequently, this analytical model was validated against experimental data and numerical results, demonstrating its capability to accurately predict the rapid stress decrease following the peak point. Finally, the sensitivity of the model parameters was discussed.

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引用次数: 0

Recognition of the cracking pattern of reinforced concrete due to 3D non-uniform corrosion under vertically varying marine exposure conditions

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110792

Yiquan Chen , Guangda Pei , Shengtao Zhen , Hetao Hou , Yifeng Ling , Qifang Liu

Cover cracking of concrete structures due to reinforcing corrosion is a crucial indicator of deterioration in their mechanical properties and plays a key role in corrosion diagnosis. Despite extensive research on two-dimensional (2D) non-uniform corrosion on cross-sections, there remains a significant gap in simulation models that capture its longitudinal variations on steel reinforcement. This limitation significantly hinders the accurate identification of crack patterns and the subsequent determination of corrosion conditions, especially under vertical variations in marine exposure conditions. This paper thereby presents a newly developed three-dimensional (3D) multi-peak Gaussian model capable of representing temporal non-uniform corrosion distributions both across cross-sections and along the longitudinal direction of steel reinforcement. By utilizing the cohesive zone model-based extended finite element method (XFEM), this study has elucidated crack patterns associated with corrosion configurations, from highly localized to more uniform distributions. The investigation of crack paths and characteristics, including initiation angle, width, and tortuosity, was validated through accelerated corrosion tests and experimental findings from the literature. These observations highlight the correlation between corrosion distribution and crack morphology, providing a foundational basis for enhanced corrosion diagnosis through concrete cracking analysis.

{"title":"Recognition of the cracking pattern of reinforced concrete due to 3D non-uniform corrosion under vertically varying marine exposure conditions","authors":"Yiquan Chen , Guangda Pei , Shengtao Zhen , Hetao Hou , Yifeng Ling , Qifang Liu","doi":"10.1016/j.engfracmech.2024.110792","DOIUrl":"10.1016/j.engfracmech.2024.110792","url":null,"abstract":"<div><div>Cover cracking of concrete structures due to reinforcing corrosion is a crucial indicator of deterioration in their mechanical properties and plays a key role in corrosion diagnosis. Despite extensive research on two-dimensional (2D) non-uniform corrosion on cross-sections, there remains a significant gap in simulation models that capture its longitudinal variations on steel reinforcement. This limitation significantly hinders the accurate identification of crack patterns and the subsequent determination of corrosion conditions, especially under vertical variations in marine exposure conditions. This paper thereby presents a newly developed three-dimensional (3D) multi-peak Gaussian model capable of representing temporal non-uniform corrosion distributions both across cross-sections and along the longitudinal direction of steel reinforcement. By utilizing the cohesive zone model-based extended finite element method (XFEM), this study has elucidated crack patterns associated with corrosion configurations, from highly localized to more uniform distributions. The investigation of crack paths and characteristics, including initiation angle, width, and tortuosity, was validated through accelerated corrosion tests and experimental findings from the literature. These observations highlight the correlation between corrosion distribution and crack morphology, providing a foundational basis for enhanced corrosion diagnosis through concrete cracking analysis.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110792"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164614","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}

引用次数: 0

Study on damage characteristics and fracture mechanisms of coal under high stress environment during blasting

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110772

Xin Zhang , Zegong Liu , Shuai Chang , Yonglin Xue , Jianyu Zhang

When using blast fracturing technology to enhance the permeability of deep coal seams, high in-situ stress makes it difficult for cracks to propagate between blast holes, posing a significant challenge for gas management in deep mines. This study combines theoretical analysis and numerical simulations to investigate the crack propagation behaviour and coalescence mechanisms of coal under various in-situ stress conditions. A theoretical model is first developed for single hole blasting to analyse the static stress distribution around the blast hole and the dynamic stress changes under blast loading. The influence of tangential static stress on crack propagation and coalescence is further investigated for simultaneous double hole initiation. The calibration of parameters in the Riedel-Hiermaier-Thoma (RHT) model for coal is performed using empirical formulas and dynamic mechanical tests, with numerical model validation conducted against fracture size distributions obtained from laboratory tests. Finally, the crack propagation and coalescence induced by single blasting and double hole blasting under varying in-situ stress conditions are simulated. The numerical results show that in-situ stress significantly suppresses both the length and number of blast-induced cracks, reducing the fractal dimension of coal damage. For double hole blasting, an angle of less than 30° between the blast hole connection line and the major principal stress direction facilitates the formation of inter-hole crack coalescence zones between the holes. Based on theoretical analysis and numerical results, it is suggested that aligning blast holes along the principal stress direction enhances permeability improvement in coal seams under high in-situ stress conditions. This study not only provides new insights into the mechanisms of crack propagation in coal blasting but also offers guidance for optimizing coal seam permeability enhancement under high in-situ stress conditions.

{"title":"Study on damage characteristics and fracture mechanisms of coal under high stress environment during blasting","authors":"Xin Zhang , Zegong Liu , Shuai Chang , Yonglin Xue , Jianyu Zhang","doi":"10.1016/j.engfracmech.2024.110772","DOIUrl":"10.1016/j.engfracmech.2024.110772","url":null,"abstract":"<div><div>When using blast fracturing technology to enhance the permeability of deep coal seams, high in-situ stress makes it difficult for cracks to propagate between blast holes, posing a significant challenge for gas management in deep mines. This study combines theoretical analysis and numerical simulations to investigate the crack propagation behaviour and coalescence mechanisms of coal under various in-situ stress conditions. A theoretical model is first developed for single hole blasting to analyse the static stress distribution around the blast hole and the dynamic stress changes under blast loading. The influence of tangential static stress on crack propagation and coalescence is further investigated for simultaneous double hole initiation. The calibration of parameters in the Riedel-Hiermaier-Thoma (RHT) model for coal is performed using empirical formulas and dynamic mechanical tests, with numerical model validation conducted against fracture size distributions obtained from laboratory tests. Finally, the crack propagation and coalescence induced by single blasting and double hole blasting under varying in-situ stress conditions are simulated. The numerical results show that in-situ stress significantly suppresses both the length and number of blast-induced cracks, reducing the fractal dimension of coal damage. For double hole blasting, an angle of less than 30° between the blast hole connection line and the major principal stress direction facilitates the formation of inter-hole crack coalescence zones between the holes. Based on theoretical analysis and numerical results, it is suggested that aligning blast holes along the principal stress direction enhances permeability improvement in coal seams under high in-situ stress conditions. This study not only provides new insights into the mechanisms of crack propagation in coal blasting but also offers guidance for optimizing coal seam permeability enhancement under high in-situ stress conditions.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110772"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164615","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}

引用次数: 0

Fatigue crack growth life prediction for butt-welded joints under block spectrum loading based on the modified strip-yield model

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110761

Saisai He, Tian Xu, Dongfang Zeng, Liantao Lu

To achieve quantitative prediction of fatigue crack growth life in welded structures under block spectrum loading, this study develops a prediction model for fatigue crack growth life in butt-weld joints based on the weight function method and the modified strip-yield model, which takes into account residual stresses and load history effects. Fatigue crack growth tests were conducted on butt-welded joints with surface defects under various loading spectra using the commonly used 16MnDR steel for railway welded bogies, to verify the applicability of the prediction model. The results show that the model can accurately predict butt-welded joints’ fatigue crack growth life. Compared to the traditional NASGRO equation, this model can effectively simulate the crack closure behavior introduced by load history, providing higher accuracy and reliability in predicting the fatigue life of butt-welded joints. The life prediction method developed in this study offers a theoretical guidance for the damage tolerance design and inspection interval optimization of welded structures.

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引用次数: 0

Effect of different CFRP strengthening methods on fracture parameters of concrete beam

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110748

Jueding Liu , Xiangqian Fan , Li Zou , Chenyu Shi

In order to investigate the effect of CFRP strengthening methods on the fracture performance of concrete structure with cracks, the fracture experiments of concrete beams with cracks strengthened by different CFRP bonding layers and prestressed CFRP were carried out in this paper. The formula for the fracture parameters of CFRP strengthened concrete beam was given by the analytical method, and the variation rules of the fracture parameters and AE parameters were analyzed by combining the acoustic emission (AE) technique. The experiment results show that, when the number of CFRP bonding layers is 3 or 4, the fracture failure behavior of concrete beams is similar to the “over-reinforced damage” mode, which is not conducive to the design and application of practical engineering. The variation rules of ultimate load, crack extension length, fracture toughness and fracture energy are analyzed, which is pointed out that bonded single-layer prestressed CFRP has the optimal strengthening effect and crack-resistant performance for concrete beam with crack. The fracture damage variables are characterized by the change rate of crack propagation length and AE energy. It is found that the damage evolution curve showed a three-stage pattern of inverted “S” and positive “S” shapes, which explains the damage and fracture behavior of CFRP strengthened concrete beam and verifies the feasibility of AE parameter characterization of damage effects.

{"title":"Effect of different CFRP strengthening methods on fracture parameters of concrete beam","authors":"Jueding Liu , Xiangqian Fan , Li Zou , Chenyu Shi","doi":"10.1016/j.engfracmech.2024.110748","DOIUrl":"10.1016/j.engfracmech.2024.110748","url":null,"abstract":"<div><div>In order to investigate the effect of CFRP strengthening methods on the fracture performance of concrete structure with cracks, the fracture experiments of concrete beams with cracks strengthened by different CFRP bonding layers and prestressed CFRP were carried out in this paper. The formula for the fracture parameters of CFRP strengthened concrete beam was given by the analytical method, and the variation rules of the fracture parameters and AE parameters were analyzed by combining the acoustic emission (AE) technique. The experiment results show that, when the number of CFRP bonding layers is 3 or 4, the fracture failure behavior of concrete beams is similar to the “over-reinforced damage” mode, which is not conducive to the design and application of practical engineering. The variation rules of ultimate load, crack extension length, fracture toughness and fracture energy are analyzed, which is pointed out that bonded single-layer prestressed CFRP has the optimal strengthening effect and crack-resistant performance for concrete beam with crack. The fracture damage variables are characterized by the change rate of crack propagation length and AE energy. It is found that the damage evolution curve showed a three-stage pattern of inverted “<em>S</em>” and positive “<em>S</em>” shapes, which explains the damage and fracture behavior of CFRP strengthened concrete beam and verifies the feasibility of AE parameter characterization of damage effects.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110748"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165001","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}

引用次数: 0

Coupled effect of corrosion and fatigue on the service life of steel cables

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110698

Jian Guo , Xiongwei Zhang

Steel cables, as the main load-bearing components of cable-supported bridges, are prone to corrosion, mechanical influences, and their coupling effects, leading to fatigue failure. This paper proposes a comprehensive fatigue failure simulation method for steel cables, quantitatively studying the service life of steel cables under the combined effects of corrosion and fatigue. Based on the principles of electrochemical corrosion, the pit growth law during the corrosion stage is derived considering the influence of current and stress during the corrosion process. Subsequently, an improved Paris formula is employed to describe the crack growth rate during the crack growth stage, and relevant parameters are calculated based on experimental data to establish a steel wire failure model. Building upon this, a simulation method for the failure process of steel cables is proposed, emphasizing the discrete properties of the material and obtaining the fatigue life of the steel wires. Through fatigue life test data, the accuracy of the method is validated.

引用次数: 0

Methodology for compiling torque load spectra of tractor power take-off shafts based on nonlinear damage accumulation

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110685

Xianghai Yan , Jinhai Zhang , Jingyun Zhang , Yiwei Wu , Junjiang Zhang , Liyou Xu

To obtain the load spectrum of the Power Take-Off (PTO) shaft during field operations under the rotary tillage condition of tractors, and in light of the limitations of traditional fatigue damage models for load spectra, a nonlinear damage model based on the Lemaitre model is proposed. This paper first establishes a dynamic torque stress testing system to acquire the PTO shaft torque loads at an engine speed of 2000 rpm, which are then preprocessed. Subsequently, the four-point rainflow counting method is employed to statistically count the mean and range values of the load signals, and a Q-Q plot is used for distribution testing. Following this, the time-domain method is utilized for frequency extrapolation to establish an 8x8 two-dimensional load spectrum, which is then converted into a one-dimensional load spectrum using the mean value method. Finally, damage assessment and life prediction of the load spectrum are conducted based on the Miner theory, the Corten-Dolan theory, and the nonlinear damage model based on the Lemaitre model. The results indicate that the mean values of the load signals follow a normal distribution, while the range values follow a Weibull distribution, and that the mean and range values are mutually independent. The peak threshold obtained through time-domain extrapolation is 380 N.m, and the trough threshold is 120 N.m, with the statistical characteristics of the extrapolated signal remaining largely consistent with those of the original signal. The fatigue life predicted by the nonlinear damage model based on the Lemaitre model is 1.76E8, which is the closest to the actual life compared to the other two models, with a calculation accuracy 724 times that of the Miner theory and 239 times that of the Corten-Dolan theory. This verifies the effectiveness and accuracy of the proposed method, providing a reference for future load spectrum life prediction and fatigue bench tests of tractors.

{"title":"Methodology for compiling torque load spectra of tractor power take-off shafts based on nonlinear damage accumulation","authors":"Xianghai Yan , Jinhai Zhang , Jingyun Zhang , Yiwei Wu , Junjiang Zhang , Liyou Xu","doi":"10.1016/j.engfracmech.2024.110685","DOIUrl":"10.1016/j.engfracmech.2024.110685","url":null,"abstract":"<div><div>To obtain the load spectrum of the Power Take-Off (PTO) shaft during field operations under the rotary tillage condition of tractors, and in light of the limitations of traditional fatigue damage models for load spectra, a nonlinear damage model based on the Lemaitre model is proposed. This paper first establishes a dynamic torque stress testing system to acquire the PTO shaft torque loads at an engine speed of 2000 rpm, which are then preprocessed. Subsequently, the four-point rainflow counting method is employed to statistically count the mean and range values of the load signals, and a Q-Q plot is used for distribution testing. Following this, the time-domain method is utilized for frequency extrapolation to establish an 8x8 two-dimensional load spectrum, which is then converted into a one-dimensional load spectrum using the mean value method. Finally, damage assessment and life prediction of the load spectrum are conducted based on the Miner theory, the Corten-Dolan theory, and the nonlinear damage model based on the Lemaitre model. The results indicate that the mean values of the load signals follow a normal distribution, while the range values follow a Weibull distribution, and that the mean and range values are mutually independent. The peak threshold obtained through time-domain extrapolation is 380 N.m, and the trough threshold is 120 N.m, with the statistical characteristics of the extrapolated signal remaining largely consistent with those of the original signal. The fatigue life predicted by the nonlinear damage model based on the Lemaitre model is 1.76E8, which is the closest to the actual life compared to the other two models, with a calculation accuracy 724 times that of the Miner theory and 239 times that of the Corten-Dolan theory. This verifies the effectiveness and accuracy of the proposed method, providing a reference for future load spectrum life prediction and fatigue bench tests of tractors.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110685"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165314","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}

引用次数: 0

Dynamic behavior of a running crack crossing mortar-granite interface with different interface inclinations

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110705

Jie Liu , Xiaohui Zeng , Weiquan Zheng , Haopeng Lai , Yulin Wang , Fei Wang , Hao Qiu

High-strength mortar is widely applied in fractured rock reinforcement due to its strong bonding strength, where crack propagation crossing the interface is commonly seen. To investigate the dynamic crack propagation behavior across the interface, A side material cleavage triangle (SMCT) sample was adopted in this study with different interface inclinations and mortar strength considered. Impact testing of a split Hopkinson pressure bar (SHPB) system was conducted and cohesive models were established to explore the penetration process of the extending crack. With the numerical result and the measurement of the crack propagation gauges (CPGs), the dynamic stress intensity factor (DSIF) was determined using an experiment-based numerical method. The investigation results show that the excited crack always propagates across the mortar-granite interface regardless of the stiffness difference, and this phenomenon remains unchanged with increasing interface inclination. For SMCT specimens, as the strength grade of mortar increases, the time taken for cracks to propagate through the interface increases. As the interfacial inclination increases, the time taken during crack penetration through the interface is longer. Using Python coding, cohesive elements can be embedded in batches in the numerical model to simulate crack propagation behavior at the interface. As the interface inclination increases, the DSIF in both the mortar and granite regions exhibits an upward trend.

{"title":"Dynamic behavior of a running crack crossing mortar-granite interface with different interface inclinations","authors":"Jie Liu , Xiaohui Zeng , Weiquan Zheng , Haopeng Lai , Yulin Wang , Fei Wang , Hao Qiu","doi":"10.1016/j.engfracmech.2024.110705","DOIUrl":"10.1016/j.engfracmech.2024.110705","url":null,"abstract":"<div><div>High-strength mortar is widely applied in fractured rock reinforcement due to its strong bonding strength, where crack propagation crossing the interface is commonly seen. To investigate the dynamic crack propagation behavior across the interface, A side material cleavage triangle (SMCT) sample was adopted in this study with different interface inclinations and mortar strength considered. Impact testing of a split Hopkinson pressure bar (SHPB) system was conducted and cohesive models were established to explore the penetration process of the extending crack. With the numerical result and the measurement of the crack propagation gauges (CPGs), the dynamic stress intensity factor (DSIF) was determined using an experiment-based numerical method. The investigation results show that the excited crack always propagates across the mortar-granite interface regardless of the stiffness difference, and this phenomenon remains unchanged with increasing interface inclination. For SMCT specimens, as the strength grade of mortar increases, the time taken for cracks to propagate through the interface increases. As the interfacial inclination increases, the time taken during crack penetration through the interface is longer. Using Python coding, cohesive elements can be embedded in batches in the numerical model to simulate crack propagation behavior at the interface. As the interface inclination increases, the DSIF in both the mortar and granite regions exhibits an upward trend.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110705"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165853","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}

引用次数: 0

Effect of fibre content on low-temperature failure strength and toughness of different sized BFRC under static and dynamic loadings: An experimental study

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110737

Liu Jin , Meiyu Fan , Wenxuan Yu , Chenxi Xie , Xiuli Du

Basalt fibres (BF) have been increasingly wide-used in many concrete structures, which also have a good application prospect in low-temperature environment. The comprehensive investigations on static/dynamic mechanical properties of Basalt Fibre-Reinforced Concrete (i.e., BFRC) have become a key scientific issue to be solved urgently. This paper aims to conduct comprehensive tests on uniaxial compressive and splitting-tensile failures of various sized BFRC (side lengths of 70 ∼ 200 mm) with various volume contents (0 ∼ 0.5 %) under static/dynamic loadings at different temperatures (20 ∼ -90 °C), with a special focus of the fibre reinforcement effect and cryogenic enhancement effect on toughness and nominal strengths as well as the corresponding size effect. Test results indicate that static/dynamic nominal strengths increase linearly with the decrease of temperature, exhibiting a significant cryogenic enhancement effect. This cryogenic effect can be enhanced by the incorporation of BF, wherein the fibre pull-out (Model-1) replaces fibre rupture (Model-2) as the dominate failure mode at low temperatures. Static/dynamic compressive toughness of BFRC is significantly improved with the adding fibre content

V_{f}

(the incorporation of 0.5 %

V_{f}

BF can bring a maximum increase of nearly 1.5 times), showing a fibre reinforcement effect, especially at ambient temperature. Nominal strengths decrease with the adding specimen sizes, performing a significant size effect, which is gradually strengthened with the decrease of temperature. However, both the incorporation of BF and the increasing loading strain-rate could weaken the size effect. Finally, according to test results, empirical formulas for the effective predication of nominal strengths of BFRC considering the quantitative coupling effects of fibre volume contents and temperatures have been proposed. The present research aims to provide effective references for safety design and large-scale applications of BFRC engineering structures under extreme cryogenic environments.

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