Pub Date : 2024-10-23DOI: 10.1016/j.tafmec.2024.104732
Understanding the repeated kinking pattern of cracks is essential for controlling the complex fracture trajectories in multilayered composites. While previous studies have explored many aspects of fractures in layered materials, the conditions governing the repeated kinking behavior under basic loading modes remain largely unrevealed. This research elucidates the continual kinking condition for a central crack in a brittle, multilayered plate with closely-parallel weak interfaces under remote shear stresses. Using the strain energy release rate (SERR) ratio criterion, we analytically derived a closed-form solution to the condition through the equivalent crack concept. The solution specifies a value domain for the intersection angle and fracture toughness ratio of weak interfaces, where the load-guided direction competes closely with the weak interface-guided direction to shape the crack trajectory into a repeated kinking pattern. Our theoretical results, validated by a series of finite element (FE) simulations, clarify how closely-parallel weak interfaces induce repeated crack kinking in multilayered materials under remote shear loading. This research paves the way for the deeper understanding of intricate crack trajectories under mixed loads in various practical applications.
{"title":"Weak interface-induced repeated kinking of a central crack in a brittle multilayered plate under remote shear loading","authors":"","doi":"10.1016/j.tafmec.2024.104732","DOIUrl":"10.1016/j.tafmec.2024.104732","url":null,"abstract":"<div><div>Understanding the repeated kinking pattern of cracks is essential for controlling the complex fracture trajectories in multilayered composites. While previous studies have explored many aspects of fractures in layered materials, the conditions governing the repeated kinking behavior under basic loading modes remain largely unrevealed. This research elucidates the continual kinking condition for a central crack in a brittle, multilayered plate with closely-parallel weak interfaces under remote shear stresses. Using the strain energy release rate (SERR) ratio criterion, we analytically derived a closed-form solution to the condition through the equivalent crack concept. The solution specifies a value domain for the intersection angle and fracture toughness ratio of weak interfaces, where the load-guided direction competes closely with the weak interface-guided direction to shape the crack trajectory into a repeated kinking pattern. Our theoretical results, validated by a series of finite element (FE) simulations, clarify how closely-parallel weak interfaces induce repeated crack kinking in multilayered materials under remote shear loading. This research paves the way for the deeper understanding of intricate crack trajectories under mixed loads in various practical applications.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532840","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 : 2024-10-23DOI: 10.1016/j.tafmec.2024.104704
The fracture problem is modeled using the Radial Point Interpolation Meshless Method (RPIM) to solve for displacements. Further, the stresses and Stress Intensity Factor (SIF) are calculated using obtained displacements. An effective numerical integral quadrature called the Element Edge point(EE) scheme is used as an alternative to conventional Gauss Quadrature to improve computational efficiency. A comparative study based on two numerical integration schemes, the Element Edge point scheme and Gauss Quadrature, is conducted on four benchmark problems of thick, cracked plates owing to plane strain conditions. The study reveals that the proposed Element Edge point (EE) scheme is computationally efficient and works well in the meshless method framework.
{"title":"A computationally efficient Element Edge point numerical integration scheme in the meshless method framework for solving fracture problems","authors":"","doi":"10.1016/j.tafmec.2024.104704","DOIUrl":"10.1016/j.tafmec.2024.104704","url":null,"abstract":"<div><div>The fracture problem is modeled using the Radial Point Interpolation Meshless Method (RPIM) to solve for displacements. Further, the stresses and Stress Intensity Factor (SIF) are calculated using obtained displacements. An effective numerical integral quadrature called the Element Edge point(EE) scheme is used as an alternative to conventional Gauss Quadrature to improve computational efficiency. A comparative study based on two numerical integration schemes, the Element Edge point scheme and Gauss Quadrature, is conducted on four benchmark problems of thick, cracked plates owing to plane strain conditions. The study reveals that the proposed Element Edge point (EE) scheme is computationally efficient and works well in the meshless method framework.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532844","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 : 2024-10-23DOI: 10.1016/j.tafmec.2024.104723
This research aims to develop a computational model that can accurately predict the fracture behavior of porous bi-directional Functionally Graded Materials (FGMs). The Voigt model for homogenization, is established to account the effects of porosity fraction and gradient distribution within the FGMs, providing valuable insights about the brittle crack propagation. The study employs the UMAT subroutine in ABAQUS software and establishes an analogy between the phase field evolution law and the heat transfer equation, enabling efficient analysis of complex fracture problems. To validate the model, 2D fracture benchmark cases are analyzed, demonstrating its ability to capture different failure modes and the intricate material behavior of porous FGMs under fracture conditions. Furthermore, newly parametric analyses, that highlights the impact of various values of porosity’s volume fraction and FGM’s power law indexes on the brittle fracture path, are conducted to further validate the effectiveness of the newly developed phase field model in predicting the fracture behavior of bi-directional porous FGMs.
{"title":"Effect of porosity gradient on fracture mechanics of bi-directional FGM structures: Phase field approach","authors":"","doi":"10.1016/j.tafmec.2024.104723","DOIUrl":"10.1016/j.tafmec.2024.104723","url":null,"abstract":"<div><div>This research aims to develop a computational model that can accurately predict the fracture behavior of porous bi-directional Functionally Graded Materials (FGMs). The Voigt model for homogenization, is established to account the effects of porosity fraction and gradient distribution within the FGMs, providing valuable insights about the brittle crack propagation. The study employs the UMAT subroutine in ABAQUS software and establishes an analogy between the phase field evolution law and the heat transfer equation, enabling efficient analysis of complex fracture problems. To validate the model, 2D fracture benchmark cases are analyzed, demonstrating its ability to capture different failure modes and the intricate material behavior of porous FGMs under fracture conditions. Furthermore, newly parametric analyses, that highlights the impact of various values of porosity’s volume fraction and FGM’s power law indexes on the brittle fracture path, are conducted to further validate the effectiveness of the newly developed phase field model in predicting the fracture behavior of bi-directional porous FGMs.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554570","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 : 2024-10-23DOI: 10.1016/j.tafmec.2024.104725
In this paper, the material parameters pertaining to fracture properties of Roller Compacted Concrete (RCC) were evaluated using the boundary element method (BEM). The fictitious crack growth length is determined by the relative size , while the individualized values of material parameters of RCC for different water-to-cement ratios were obtained. In this study, the three-parameter Weibull fracture statistical model was proposed for the first time to analyze the discreteness of these individualized values of material parameters of RCC. The statistical analysis minimum value of material parameters of each group is obtained. The failure curves of each group of RCC were predicted from the three-parameter Weibull fracture statistical model, and the simple calculation model for material parameters was validated. Further, a two-point design method was proposed for RCC material parameters with varying strengths and water-to-cement ratios.
{"title":"Improved probabilistic design method to quantify the fracture properties of roller compacted concrete","authors":"","doi":"10.1016/j.tafmec.2024.104725","DOIUrl":"10.1016/j.tafmec.2024.104725","url":null,"abstract":"<div><div>In this paper, the material parameters pertaining to fracture properties of Roller Compacted Concrete (RCC) were evaluated using the boundary element method (BEM). The fictitious crack growth length <span><math><mrow><mi>Δ</mi><msub><mi>a</mi><mtext>fic</mtext></msub></mrow></math></span> is determined by the relative size <span><math><mrow><mrow><mo>(</mo><mi>T</mi><mo>-</mo><msub><mi>a</mi><mn>0</mn></msub><mo>)</mo></mrow><mo>/</mo><msub><mi>d</mi><mi>i</mi></msub></mrow></math></span>, while the individualized values of material parameters <span><math><mrow><mo>(</mo><msub><mi>K</mi><mtext>IC</mtext></msub><mo>&</mo><msub><mi>f</mi><mtext>t</mtext></msub><mo>)</mo></mrow></math></span> of RCC for different water-to-cement ratios were obtained. In this study, the three-parameter Weibull fracture statistical model was proposed for the first time to analyze the discreteness of these individualized values of material parameters <span><math><mrow><mo>(</mo><msub><mi>K</mi><mtext>IC</mtext></msub><mo>&</mo><msub><mi>f</mi><mtext>t</mtext></msub><mo>)</mo></mrow></math></span> of RCC. The statistical analysis minimum value of material parameters <span><math><mrow><mo>(</mo><msub><mi>K</mi><mtext>IC</mtext></msub><mo>&</mo><msub><mi>f</mi><mtext>t</mtext></msub><mo>)</mo></mrow></math></span> of each group is obtained. The failure curves of each group of RCC were predicted from the three-parameter Weibull fracture statistical model, and the simple calculation model for material parameters <span><math><mrow><mo>(</mo><msub><mi>K</mi><mtext>IC</mtext></msub><mo>&</mo><msub><mi>f</mi><mtext>t</mtext></msub><mo>)</mo></mrow></math></span> was validated. Further, a two-point design method was proposed for RCC material parameters <span><math><mrow><mo>(</mo><msub><mi>K</mi><mtext>IC</mtext></msub><mo>&</mo><msub><mi>f</mi><mtext>t</mtext></msub><mo>)</mo></mrow></math></span> with varying strengths and water-to-cement ratios.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554572","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 : 2024-10-22DOI: 10.1016/j.tafmec.2024.104731
The intralaminar tensile failure of 2D woven composites under dynamic tensile load was investigated in this paper. Compact tension samples were tested at high loading rate with an electromagnetic Hopkinson bar system. The strain field was obtained with high-speed imaging and digital image correlation, and the J-integral method was employed to obtain the fracture toughness and corresponding R-curve. The continuum damage evolution of intralaminar failure was then analyzed by tracking the opening near the initial crack tip. It is found that the dynamic intralaminar fracture toughness is decreased by 51% compared to the quasi-static condition, the continuum damage evolution and its dependence on loading rate have been reported as well. The failure mechanisms were studied with thermal imaging and scanned electron microscopy, shorter fibre pull-out length and thinner failure process zone may be responsible for the reduced toughness at high loading rate.
本文研究了二维编织复合材料在动态拉伸载荷下的层内拉伸破坏。利用电磁霍普金森棒系统对紧凑拉伸样品进行了高加载率测试。利用高速成像和数字图像相关技术获得了应变场，并采用 J 积分法获得了断裂韧性和相应的 R 曲线。然后，通过跟踪初始裂纹尖端附近的开口，分析了层内破坏的连续损伤演化。研究发现，与准静态相比，动态层内断裂韧性降低了 51%，同时还报告了连续损伤演变及其与加载速率的关系。通过热成像和扫描电子显微镜对破坏机制进行了研究，较短的纤维拉出长度和较薄的破坏过程区可能是高加载速率下韧性降低的原因。
{"title":"Dynamic tensile intralaminar fracture and continuum damage evolution of 2D woven composite laminates at high loading rate","authors":"","doi":"10.1016/j.tafmec.2024.104731","DOIUrl":"10.1016/j.tafmec.2024.104731","url":null,"abstract":"<div><div>The intralaminar tensile failure of 2D woven composites under dynamic tensile load was investigated in this paper. Compact tension samples were tested at high loading rate with an electromagnetic Hopkinson bar system. The strain field was obtained with high-speed imaging and digital image correlation, and the J-integral method was employed to obtain the fracture toughness and corresponding R-curve. The continuum damage evolution of intralaminar failure was then analyzed by tracking the opening near the initial crack tip. It is found that the dynamic intralaminar fracture toughness is decreased by 51% compared to the quasi-static condition, the continuum damage evolution and its dependence on loading rate have been reported as well. The failure mechanisms were studied with thermal imaging and scanned electron microscopy, shorter fibre pull-out length and thinner failure process zone may be responsible for the reduced toughness at high loading rate.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572529","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 : 2024-10-22DOI: 10.1016/j.tafmec.2024.104730
Maraging steel, 18Ni300, is a high-performance material that shows promising potential for various industrial applications. Selective Laser Melting is utilized in the manufacturing of high-value components. Understanding the fatigue mechanisms of this material is imperative, as its fatigue life is influenced by both surface and internal porosity, as well as defects produced when manufacturing the objects due to the patterns used. The main objective is to analyze the characterization of these pores and clarify their relationship with the fatigue properties of the material under study. Compact tension specimens were manufactured by selective laser melting at three angles (0°, 45° and 90°) with respect to the crack growing direction and fatigue tests were performed. A study of the porosity of the sample was conducted, which established a correlation between the printing angle, growing rate (da/dN curves), and the porosity that is categorised through the aspect ratio and the circularity ratio. It is shown that all manufacturing orientations generate similar pore sizes and area, but the 45° orientation induces pore with slightly higher circularity ratio. The results indicate that the faster fatigue crack growth might be linked to the slight increase in pore area and circularity, and this was observed for 45°.
{"title":"Characterisation of 18Ni 300 steel CT specimens in a fatigue test manufactured by selective laser melting at 0°, 45° and 90°","authors":"","doi":"10.1016/j.tafmec.2024.104730","DOIUrl":"10.1016/j.tafmec.2024.104730","url":null,"abstract":"<div><div>Maraging steel, 18Ni300, is a high-performance material that shows promising potential for various industrial applications. Selective Laser Melting is utilized in the manufacturing of high-value components. Understanding the fatigue mechanisms of this material is imperative, as its fatigue life is influenced by both surface and internal porosity, as well as defects produced when manufacturing the objects due to the patterns used. The main objective is to analyze the characterization of these pores and clarify their relationship with the fatigue properties of the material under study. Compact tension specimens were manufactured by selective laser melting at three angles (0°, 45° and 90°) with respect to the crack growing direction and fatigue tests were performed. A study of the porosity of the sample was conducted, which established a correlation between the printing angle, growing rate (da/dN curves), and the porosity that is categorised through the aspect ratio and the circularity ratio. It is shown that all manufacturing orientations generate similar pore sizes and area, but the 45° orientation induces pore with slightly higher circularity ratio. The results indicate that the faster fatigue crack growth might be linked to the slight increase in pore area and circularity, and this was observed for 45°.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572530","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 : 2024-10-21DOI: 10.1016/j.tafmec.2024.104728
In underground engineerings, the evolution of the stress state in the surrounding rocks can effectively reveal its fracture mechanism. To precisely describe this microscopic information, the present study utilizes the three-dimensional Grain-based model based on Particle Flow Code (PFC3D-GBM) to construct a square numerical specimen with a pre-existing hole representing a tunnel and subjected it to uniaxial loading. In this model, different types of mineral structures and internal force chain networks are distinguished at a three-dimensional scale. Furthermore, the evolution of force chain networks in the top, bottom, left and right regions around the tunnel is quantitatively characterized. The anti-fracture capability depending on stress state of various structures is calculated and then the fracture mechanism from the point of anti-fracture capability is discussed. The research results indicate that at at the beginning of loading, some red force chains with higher level have appeared on both sides of the tunnel. As the load goes on, red force chain network extending from both sides of the tunnel to the upper and lower ends of the specimen have emerged. The average value and sum value of all force chains show an increasing trend before the peak load and a decreasing trend after the peak load. The average value of force chains within a specific structure can accurately reflect the microscopic mechanical properties of that structure. The average values of force chains on the left and right sides of the tunnel are higher, both in terms of starting points and ascending rates, than those in the upper and lower regions of the tunnel. The orientation distribution of all force chains is relatively uniform, but force chains with higher level are generally align with the loading direction. The fundamental reason for the high degree of fragmentation on the left and right sides of the tunnel is that these regions bear more external load than the upper and lower regions, rather than being inherently more prone to fracture.
{"title":"Stress evolution in rocks around tunnel under uniaxial loading: Insights from PFC3D-GBM modelling and force chain analysis","authors":"","doi":"10.1016/j.tafmec.2024.104728","DOIUrl":"10.1016/j.tafmec.2024.104728","url":null,"abstract":"<div><div>In underground engineerings, the evolution of the stress state in the surrounding rocks can effectively reveal its fracture mechanism. To precisely describe this microscopic information, the present study utilizes the three-dimensional Grain-based model based on Particle Flow Code (PFC3D-GBM) to construct a square numerical specimen with a pre-existing hole representing a tunnel and subjected it to uniaxial loading. In this model, different types of mineral structures and internal force chain networks are distinguished at a three-dimensional scale. Furthermore, the evolution of force chain networks in the top, bottom, left and right regions around the tunnel is quantitatively characterized. The anti-fracture capability depending on stress state of various structures is calculated and then the fracture mechanism from the point of anti-fracture capability is discussed. The research results indicate that at at the beginning of loading, some red force chains with higher level have appeared on both sides of the tunnel. As the load goes on, red force chain network extending from both sides of the tunnel to the upper and lower ends of the specimen have emerged. The average value and sum value of all force chains show an increasing trend before the peak load and a decreasing trend after the peak load. The average value of force chains within a specific structure can accurately reflect the microscopic mechanical properties of that structure. The average values of force chains on the left and right sides of the tunnel are higher, both in terms of starting points and ascending rates, than those in the upper and lower regions of the tunnel. The orientation distribution of all force chains is relatively uniform, but force chains with higher level are generally align with the loading direction. The fundamental reason for the high degree of fragmentation on the left and right sides of the tunnel is that these regions bear more external load than the upper and lower regions, rather than being inherently more prone to fracture.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532845","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 : 2024-10-20DOI: 10.1016/j.tafmec.2024.104727
Motivated by the increasingly important role that polymers have in structural applications, this study aims to analyse the structural integrity of polymers through residual strength diagrams. The polymers analysed have been thermoplastics, Polylactic acid (PLA), Polyethylene terephthalate glycol-modified (PET-G) and Polyamide 12 (PA-12), as well as a thermosetting resin, processed through different additive manufacturing techniques: Fused Deposition Modelling (FDM) in the case of PLA, PET-G, Selective Laser Sintering (SLS) for PA-12 and Digital Light Processing (DLP) for the thermosetting resin. In addition, PA-12 manufactured by injection moulding was also included in this study. To obtain the residual strength diagrams, mechanical tests have been carried out on smooth specimens and on specimens with cracks of different lengths. From the analysis of the results, a prediction has been obtained by fitting a semi-empirical model that describes the structural integrity in the areas of microstructurally short cracks, long cracks and physically short cracks.
{"title":"Structural integrity of polymers processed by additive manufacturing techniques using residual strength diagrams","authors":"","doi":"10.1016/j.tafmec.2024.104727","DOIUrl":"10.1016/j.tafmec.2024.104727","url":null,"abstract":"<div><div>Motivated by the increasingly important role that polymers have in structural applications, this study aims to analyse the structural integrity of polymers through residual strength diagrams. The polymers analysed have been thermoplastics, Polylactic acid (PLA), Polyethylene terephthalate glycol-modified (PET-G) and Polyamide 12 (PA-12), as well as a thermosetting resin, processed through different additive manufacturing techniques: Fused Deposition Modelling (FDM) in the case of PLA, PET-G, Selective Laser Sintering (SLS) for PA-12 and Digital Light Processing (DLP) for the thermosetting resin. In addition, PA-12 manufactured by injection moulding was also included in this study. To obtain the residual strength diagrams, mechanical tests have been carried out on smooth specimens and on specimens with cracks of different lengths. From the analysis of the results, a prediction has been obtained by fitting a semi-empirical model that describes the structural integrity in the areas of microstructurally short cracks, long cracks and physically short cracks.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532841","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 : 2024-10-20DOI: 10.1016/j.tafmec.2024.104729
This paper explores the influence of loading rate on mode II fracture failure in rock. Impact experiments were performed on samples of SCC at five different impact pressures via an SHPB system. This study reveals the correlations among the peak load, fracture toughness, and dynamic elastic modulus of rock mode II fractures under diverse loading rates, as well as the alterations in fracture trajectories. Simultaneously, PFC3D discrete element software has been adopted to numerically simulate the experiments and analysis of the fracture process of rocks and the variations in crack quantity and energy from a microscopic perspective. The results suggest that dynamic mode II fracture tends to increase as the loading rate increases and that the loading rate affects the fracture failure trajectory of a sample. Concurrently, as loading increased, the percentage of shear cracks in the samples gradually decreased, whereas the proportion of tensile cracks gradually increased, indicating that the samples experienced compressive stress after mode II fracture occurred at high loading rates. The proportion of energy absorbed by the samples for crack initiation and development, as well as the kinetic energy of the particles, initially tends to decrease but then increases with increasing loading rate, which is related to whether the loading rate generates secondary cracks. It is hypothesized that there exists a critical loading rate that triggers secondary cracks in SCC samples.
本文探讨了加载速率对岩石中模式 II 断裂破坏的影响。通过 SHPB 系统对 SCC 样品进行了五种不同冲击压力下的冲击实验。该研究揭示了不同加载速率下岩石模式 II 断裂的峰值载荷、断裂韧性和动态弹性模量之间的相关性，以及断裂轨迹的变化。同时，采用 PFC3D 离散元软件进行数值模拟实验，从微观角度分析了岩石的断裂过程以及裂缝数量和能量的变化。结果表明，随着加载速率的增加，动态模式 II 断裂有增加的趋势，加载速率会影响样品的断裂破坏轨迹。同时，随着加载速率的增加，样品中剪切裂纹的比例逐渐减少，而拉伸裂纹的比例逐渐增加，这表明在高加载速率下发生模式 II 断裂后，样品受到了压应力。样品在裂纹萌发和发展过程中吸收的能量比例以及颗粒的动能最初呈下降趋势，但随着加载速率的增加又呈上升趋势，这与加载速率是否会产生二次裂纹有关。据此推测，在 SCC 样品中存在一个引发二次裂纹的临界加载速率。
{"title":"Influence of loading rate on the mode II fracture characteristics of SCC samples: Experiments and numerical simulations","authors":"","doi":"10.1016/j.tafmec.2024.104729","DOIUrl":"10.1016/j.tafmec.2024.104729","url":null,"abstract":"<div><div>This paper explores the influence of loading rate on mode II fracture failure in rock. Impact experiments were performed on samples of SCC at five different impact pressures via an SHPB system. This study reveals the correlations among the peak load, fracture toughness, and dynamic elastic modulus of rock mode II fractures under diverse loading rates, as well as the alterations in fracture trajectories. Simultaneously, PFC3D discrete element software has been adopted to numerically simulate the experiments and analysis of the fracture process of rocks and the variations in crack quantity and energy from a microscopic perspective. The results suggest that dynamic mode II fracture tends to increase as the loading rate increases and that the loading rate affects the fracture failure trajectory of a sample. Concurrently, as loading increased, the percentage of shear cracks in the samples gradually decreased, whereas the proportion of tensile cracks gradually increased, indicating that the samples experienced compressive stress after mode II fracture occurred at high loading rates. The proportion of energy absorbed by the samples for crack initiation and development, as well as the kinetic energy of the particles, initially tends to decrease but then increases with increasing loading rate, which is related to whether the loading rate generates secondary cracks. It is hypothesized that there exists a critical loading rate that triggers secondary cracks in SCC samples.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532842","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 : 2024-10-19DOI: 10.1016/j.tafmec.2024.104726
The concept of debonding entropy provides insight into the physical mechanisms of fracture. It sheds light on how the fracture phenomenon is more intimately related to degradation and entropy. This paper aims to investigate the relationships between debonding entropy and fundamental concepts in fracture mechanics. A direct, simple relationship between debonding entropy and the J-integral value at fracture is developed and validated. The validation of this relation displays the connection between fracture mechanics and entropic degradation.
{"title":"On the relation between entropy and crack driving force","authors":"","doi":"10.1016/j.tafmec.2024.104726","DOIUrl":"10.1016/j.tafmec.2024.104726","url":null,"abstract":"<div><div>The concept of debonding entropy provides insight into the physical mechanisms of fracture. It sheds light on how the fracture phenomenon is more intimately related to degradation and entropy. This paper aims to investigate the relationships between debonding entropy and fundamental concepts in fracture mechanics. A direct, simple relationship between debonding entropy and the J-integral value at fracture is developed and validated. The validation of this relation displays the connection between fracture mechanics and entropic degradation.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532617","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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