Engineering Fracture Mechanics最新文献

{"title":"Relationship between crack initiation stress and uniaxial compressive strength of brittle rocks","authors":"Baicun Yang ,&nbsp;Chuyang Song ,&nbsp;Yongting Duan ,&nbsp;Zihan Zhao","doi":"10.1016/j.engfracmech.2024.110768","DOIUrl":"10.1016/j.engfracmech.2024.110768","url":null,"abstract":"<div><div>Clarifying the reasonable value range of the stress threshold for brittle rock under uniaxial compression has high theoretical and practical significance for predicting the failure of an engineering rock mass. Although much attention has been directed toward the experimental investigation of the ratio of crack initiation stress to uniaxial compressive strength (CI/UCS) in recent years, the ratio’s reasonable value range has not be accurately obtained owing to the lack of relevant theoretical work. By combining renormalization group theory, a rock damage constitutive model, and a CI identification method, this study derived the theoretical expression of CI/UCS for brittle rock and calculated the reasonable value range of CI/UCS as 0.43–0.52. The value range of CI/UCS was verified by 8 experimental results obtained for Longmaxi shale with different bedding angles, and the results of previous experiments on 385 brittle rocks with different lithologies obtained from different locations. On this basis, the main factors affecting CI/UCS in brittle rocks were analyzed, and the applicability of the theoretical calculation results was discussed. The relevant research results are of great interest to theoretical research on the rock stress threshold and can be useful as guidelines in engineering practice.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110768"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164618","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}

{"title":"Localized necking predictions for an imperfect sheet using a porous plastic constitutive relation with two porosity parameters","authors":"I.A. Khan ,&nbsp;A. Benallal ,&nbsp;A.A. Benzerga ,&nbsp;F. Moussy ,&nbsp;A. Needleman","doi":"10.1016/j.engfracmech.2024.110711","DOIUrl":"10.1016/j.engfracmech.2024.110711","url":null,"abstract":"<div><div>The role of void nucleation and void growth in triggering localized necking in biaxially stretched sheets is investigated using a rate independent porous plastic constitutive relation with two porosity parameters; one associated with the void volume fraction and the other associated with the weakening effect of void shape changes in shear dominated stress states. Proportional straining plane stress calculations are carried out for ratios of imposed in-plane principal strain rates ranging from <span><math><mrow><mo>≈</mo><mo>−</mo><mn>1</mn></mrow></math></span> (shear dominated) to 1 (equal biaxial tension). The framework for the localized necking calculations is that in which an imperfection band triggers the onset of localized necking as defined by a loss of ellipticity of the governing equations in the imperfection band. The imperfection band is taken to be either an increase in initial void volume fraction or an increase in the volume fraction of void nucleating particles. The predicted forming limit curves are compared with predictions for a localized necking bifurcation of a rigid-plastic solid. For negative values of the imposed strain ratio, except for near in-plane shear where the second porosity reduces the critical strains, the predicted critical localization strains and the predicted critical localization band orientations differ little from the corresponding critical values predicted by a rigid plastic bifurcation analysis. For biaxial tensile states the critical localization strains are sensitive to the nature and magnitude of the imperfection. When void nucleation occurs over a very narrow range of strain or stress, void nucleation and the onset of localized necking can coincide.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110711"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165257","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}

{"title":"A nonlocal macro-meso-scale damage model based modeling for crack propagation in ferroelectric materials","authors":"Feng Xue,&nbsp;Jingyu Wang,&nbsp;Xiaozhou Xia,&nbsp;Xiaofan Gou","doi":"10.1016/j.engfracmech.2024.110712","DOIUrl":"10.1016/j.engfracmech.2024.110712","url":null,"abstract":"<div><div>The accurate simulation of crack growth for ferroelectric materials plays a crucial role in the application of ferroelectric materials in electronic devices. In recent years, a nonlocal macro-<em>meso</em>-scale consistent damage (NMMD) model has been proposed for simulating the crack propagation in brittle materials, which offers the advantage of higher efficiency compared to the phase-field method. Different from the phase field method, this model does not need to solve the phase field equation at the same time. Therefore, the degree of freedom in solving can be reduced, thereby reducing the computational workload. In this paper, the authors proposed a new integration strategy for microscopic damage and devised a simple and efficient implementation of the NMMD model for the modelling of quasi-static fracture in the general purpose commercial software developer, COMSOL Multiphysics based on the finite element method (FEM) and studied the crack propagation for ferroelectric materials under the applied stress and electric fields. Different from the original NMMD model, only the tensile stress induced geometric damage is accounted for crack propagation by using the decomposition of elastic strain energy. The effects of different crack-face conditions, electrical boundary conditions and the electromechanical loading for crack growth of ferroelectric materials have been considered in our FEM simulation are discussed in this work.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110712"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165315","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}

{"title":"Effect of microwave irradiation on the breaking and linear cutting of hard rock","authors":"Chuncheng Sun ,&nbsp;Yixin Zhao ,&nbsp;Yirui Gao ,&nbsp;Sen Gao ,&nbsp;Guangpei Zhu ,&nbsp;Xiaodong Guo ,&nbsp;Ronghuan Xie","doi":"10.1016/j.engfracmech.2024.110729","DOIUrl":"10.1016/j.engfracmech.2024.110729","url":null,"abstract":"<div><div>Microwave technology, emerging as a novel approach to rock-breaking, holds significant promise in the realm of auxiliary mechanical pick rock breaking. In view of the problems existing in the hard rock breaking such as low efficiency and difficulty in one-time cutting, this study conducted experimental research using a method combining microwave irradiation and linear cutting with conical picks. The comprehensive temperature distribution of the rock is reproduced by 3D technology after microwave irradiation, defined the high-temperature zone and calculated the surface area. Moreover, analyzing the relationship between temperature and cutting force. And the effect of microwave-assisted conical pick rock breaking was quantified in terms of cutting force, cutting effect, and energy consumption. The results indicate that microwave irradiation induces heating in hard rock, leading to the formation of fissures and even partial fragmentation of rocks. The thermal damage effect of microwave is determined by the differences in the physical and mechanical properties of different rocks. In the experiment, basalt has the best heating effect and sandstone has the best fracturing effect. Compared to non-microwave, microwave (6 kW,60 s) irradiation reduces the cutting force, improves the effect of rock breaking, and reduces the work done (<em>E</em>) by the cutting force and the mechanical specific energy (<em>MSE</em>). Microwave irradiation-assisted mechanical rock breaking is better for sandstone, moderate for basalt, and inferior for granite in this study.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110729"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165317","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}

{"title":"Experimental study on the dynamic direct tensile fracture mechanism of thermally damaged sandstone","authors":"Ming Li ,&nbsp;Fuqiang Zhu ,&nbsp;Ketong Wu ,&nbsp;Hai Pu ,&nbsp;Yanlong Chen ,&nbsp;Jiazhi Zhang ,&nbsp;Jishuo Deng","doi":"10.1016/j.engfracmech.2024.110728","DOIUrl":"10.1016/j.engfracmech.2024.110728","url":null,"abstract":"<div><div>Understanding the dynamic tensile fracture mechanism of thermally damaged coal-rock media is crucial for developing scientific prevention and early warning systems in geotechnical engineering, particularly for high-temperature dynamic environments like underground coal gasification. This study employs a high-temperature loading system and a split Hopkinson tension bar (SHTB) experiment system to conduct dynamic direct tensile failure experiments on high-temperature thermally damaged coal sandstone. Three-dimensional cross-sectional scanners, scanning electron microscopy (SEM), and computed tomography are used to reveal the macroscopic and microscopic mechanisms of dynamic direct tensile fracture in thermally damaged coal sandstone. Experimental results show that temperature has a more significant effect on the macroscopic fracture characteristics of coal-rock media than impact velocity. As the impact velocity increases, the number of macroscopic debris gradually increases. However, the rise in temperature causes a deviation between the fracture plane normal and the tensile load direction and reduces the size of macroscopic debris. The macroscopic cross-sectional structural parameters of tensile failure exhibit an exponential change with increasing temperature and impact velocity. However, the change in cross-sectional structural parameters with temperature is significantly greater than with impact velocity. Additionally, the brittleness of the samples initially increases and then rapidly decreases with rising temperature, with the influence of high temperature on the rocks’ brittle-ductile properties gradually intensifies. The evolutionary pattern of microcracks and microporous defects within the coal-rock media shows that the formation and expansion of microcracks and the decoupling of mineral interfaces due to temperature significantly influence the rock’s physical and mechanical properties. At lower temperatures, the coal-rock media exhibits relatively smooth brittle fracture characteristics. However, under high-temperature conditions, the rock damage effect intensifies, and the cross-sectional morphological characteristics transition from brittle to ductile, exhibiting more complex and rough fracture forms. The increase in impact velocity mainly affects the undulation and roughness characteristics of the cross-sectional structure. The impact velocity has a lesser effect on the morphological characteristics of the coal-rock media’s cross-section at a certain temperature.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110728"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165915","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}

{"title":"A spatiotemporal deep learning framework for prediction of crack dynamics in heterogeneous solids: Efficient mapping of concrete microstructures to its fracture properties","authors":"Rasoul Najafi Koopas ,&nbsp;Shahed Rezaei ,&nbsp;Natalie Rauter ,&nbsp;Richard Ostwald ,&nbsp;Rolf Lammering","doi":"10.1016/j.engfracmech.2024.110675","DOIUrl":"10.1016/j.engfracmech.2024.110675","url":null,"abstract":"<div><div>A spatiotemporal deep learning framework is proposed that is capable of two-dimensional full-field prediction of fracture in concrete mesostructures. This framework not only predicts fractures but also captures the entire history of the fracture process, from the crack initiation in the interfacial transition zone (ITZ) to the subsequent propagation of the cracks in the mortar matrix. Additionally, a convolutional neural network (CNN) is developed which is capable of predicting the averaged stress–strain curve of the mesostructures. The UNet modeling framework, which comprises an encoder–decoder section with skip connections, is used as the deep learning surrogate model. Training and test data are generated from high-fidelity fracture simulations of randomly generated concrete mesostructures. These mesostructures include geometric variabilities such as different aggregate particle geometrical features, spatial distribution, and the total volume fraction of aggregates. The fracture simulations are carried out in Abaqus/CAE, utilizing the cohesive phase-field fracture modeling technique as the fracture modeling approach. In this work, to reduce the number of training datasets, the spatial distribution of three sets of material properties for three-phase concrete mesostructures, along with the spatial phase-field damage index, are fed to the UNet to predict the corresponding stress and spatial damage index at the subsequent step. It is shown that after the training process using this methodology, the UNet model is capable of accurately predicting damage on the unseen test dataset by using just 470 datasets. Moreover, another novel aspect of this work is the conversion of irregular finite element data into regular grids using a developed pipeline. This approach allows for the implementation of less complex UNet architecture and facilitates the integration of phase-field fracture equations into surrogate models for future developments.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110675"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165917","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}

{"title":"The dominating dimensionless numbers of adiabatic shear localization","authors":"Zhi-yong Yin ,&nbsp;Xiao-wei Chen","doi":"10.1016/j.engfracmech.2024.110724","DOIUrl":"10.1016/j.engfracmech.2024.110724","url":null,"abstract":"<div><div>Adiabatic shear is a complex phenomenon involving thermo-mechanical coupled failure mechanisms, which is affected by material properties, loads, and geometries. In this study, four dimensionless numbers which only contain input parameters and can fully reflect the influence of adiabatic shear are determined by reducing the conservation equations of shear localization to dimensionless terms. The dimensional analysis method of adiabatic shear, along with predictive models for the characteristic parameters of adiabatic shear, are systematically provided by revealing the physical significance of the dimensionless numbers. Based on data analysis, a dimensional analysis method of adiabatic shear for multi-physical processes is proposed, which has been successfully applied to explosively-driven metal shells, to realize the prediction and control of adiabatic shear. This study demonstrates that the prediction models of adiabatic shear-band spacing and width can be unified through a relationship involving the Prandtl number, <em>P</em>_r. Furthermore, the classical prediction models of spacing and width are improved based on the experimental data. It is clearly pointed out that the more favorable the formation of shear localization, the smaller the width and spacing of the shear band, which illustrates the influence of material properties and loads on the spatial distribution of shear bands. In addition, a new prediction model for the propagation velocity of the shear band including <em>P</em>_r is proposed by using dimensional analysis. Compared with the classical model, the new model has higher accuracy, and can correctly reflect the influence of loads, material mechanical and thermophysical properties on the shear-band velocity.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110724"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165923","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}

{"title":"Dynamic mechanical response and failure behaviour of single-flawed rocks under combined compression-shear loading","authors":"Zhi Cai ,&nbsp;Feng Dai ,&nbsp;Zelin Yan ,&nbsp;Yi Liu ,&nbsp;Biao Zhang ,&nbsp;Mingdong Wei","doi":"10.1016/j.engfracmech.2024.110777","DOIUrl":"10.1016/j.engfracmech.2024.110777","url":null,"abstract":"<div><div>In deep underground engineering projects, flawed rocks are often subjected to dynamic compression-shear loading owing to the arbitrary distribution of structural planes in rock mass. Understanding the dynamic mechanical response of flawed rocks under compression-shear loading is of great significance for rock engineering construction. In this study, the mechanical response and failure behaviors of flawed rock specimens subjected to dynamic compression-shear loading are studied by introducing an oblique cubic flawed specimen into the split Hopkinson pressure bar (SHPB) tests. Firstly, the stress distribution of the oblique flawed specimen is analyzed by using the finite element method. Numerical results show that the stress concentration zones are distributed along the short diagonal of oblique rock specimens, which validates the oblique specimen is an effective method to investigate the dynamic compression-shear failure behaviors of flawed rocks. Then, dynamic impact tests are conducted on oblique flawed rocks with different configurations. The experimental results indicate that the oblique angle, the flaw inclination angle, and the strain rate significantly affect the dynamic strength and deformation characteristics of the rock. Utilizing high-speed digital image correlation (DIC), the progressive cracking behavior and failure modes of flawed rocks under dynamic compression-shear loading are analyzed. The mixed compression-shear cracking dominates the failure of flawed rock specimens. In addition, the energy dissipation density and fragmentation degree also exhibit a strong strain rate dependency, and they are positively correlated with the dynamic strength of the flawed rocks.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110777"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164564","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}

{"title":"Effect of complex stress states on creep rupture life of nickel-based superalloys: Mechanisms and modeling","authors":"Sui Tianxiao ,&nbsp;Zhang Yuman ,&nbsp;Xiang Shouliang ,&nbsp;Shi Duoqi","doi":"10.1016/j.engfracmech.2024.110749","DOIUrl":"10.1016/j.engfracmech.2024.110749","url":null,"abstract":"<div><div>This study investigates the effects of complex stress states on creep rupture life of nickel-based superalloys. Creep experiments were conducted at 900 °C on both smooth and single-hole plate specimens. A viscoplastic constitutive model was developed to simulate the creep behavior of single-hole plates and V-notched bars. The analysis offered a detailed mechanical explanation for the significant differences in creep rupture life observed among these differently structured specimens. This investigation incorporated the effects of complex stress states into the Monkman-Grant relationship, resulting in a new creep life model that accounts for stress triaxiality. The results indicate that the increased stress triaxiality significantly extends the creep life of V-notched bars. In contrast, the single-hole plates, which approach a uniaxial stress state, exhibit a creep rupture life closely aligning with that of the standard smooth plates. The proposed model accurately predicts the creep rupture life of both single-hole plates and V-notched bars, with all predictions falling within a threefold scatter band.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110749"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164582","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}

{"title":"Experimental and numerical investigation of groove-assisted impact rock-breaking","authors":"Zhengkuo Ma ,&nbsp;Chunshun Zhang ,&nbsp;Zenghui Liu ,&nbsp;Tong Ye ,&nbsp;Congying Li ,&nbsp;Wei Wei ,&nbsp;Jie Dong","doi":"10.1016/j.engfracmech.2024.110769","DOIUrl":"10.1016/j.engfracmech.2024.110769","url":null,"abstract":"<div><div>Groove-assisted impact rock-breaking represents a critical mechanical method for fracturing rocks; however, comprehending its underlying mechanisms governing fracture initiation and propagation remains incomplete. This paper aims to fill this knowledge gap by first establishing a dedicated test bench for groove-assisted impact rock-breaking and conducting double-impact head experiments with varying spacings. Subsequently, a finite discrete element method (FDEM) model is developed, incorporating zero-thickness cohesive elements, to validate and refine the numerical simulations against experimental outcomes. The investigation then systematically explores the impacts of double-head and multi-head rock-breaking to elucidate the dynamic evolution of stress fields and damage processes throughout the rock-breaking sequence. This includes the formation of dense cores, the initiation and propagation of fractures, and the eventual propagation of splitting damage. Noteworthy findings of this study include the identification and characterization of four distinct damage zones: an intermediate impact breakage zone dominated by shear damage, an annular extrusion damage zone typified by tensile failure, a primary surface cracking damage zone, and an interconnecting damage zone between dual impact heads, both characterized by tensile damage. Additionally, the study examines variations in penetration depth relative to the number and positioning of impact heads under conditions of equal energy input. These insights significantly enhance our understanding of the fracture mechanics involved in groove-assisted impact rock-breaking and lay the groundwork for enhancing rock-breaking efficiency.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110769"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164589","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}