Engineering Fracture Mechanics最新文献

{"title":"Numerical investigation on the fragmentation behaviour of hard rock with a pre-existing crack under TBM cutter using cohesive zone model","authors":"Wei Gao ,&nbsp;Bin Liu ,&nbsp;Jie Hu ,&nbsp;Y.T. Feng ,&nbsp;Kui Zhang ,&nbsp;Xuejun Zheng","doi":"10.1016/j.engfracmech.2025.110943","DOIUrl":"10.1016/j.engfracmech.2025.110943","url":null,"abstract":"<div><div>This paper presents a numerical investigation into the fragmentation behaviour of pressure-dependent rock with a pre-existing crack under a TBM cutter. To achieve this purpose, an intrinsic cohesive zone model is employed for modelling the initiation, propagation, intersection and closure of cracks. Additionally, the bilinear constitutive law for the cohesive elements is employed to consider the pressure-dependent behaviour of the hard rock with a tensile strength of 6.5 MPa. Firstly, the effectiveness of rock model is validated by comparing the numerical results with the outcomes of the uniaxial compression and triaxial compression experiments. Subsequently, the fragmentation process of the rock under the indention of an elastic cutter of TBM is simulated to numerically investigate the effects of the position and geometry of the pre-existing crack, and the confining pressure on the rock fragmentation. It is found that the depth, length and position of the pre-existing crack, as well as the confining pressure, have a significant effect on the response and fragmentation of rock , including the crack pattern, the crack area, and the contact force from the TBM cutter. Specifically, a deeper and shorter pre-existing crack farther from the contact zone leads to higher contact force and more initial cracks. Furthermore, cracks in the vicinity of the contact zone are typically induced by shear (i.e. mode-II cracks), while the cracks below the pre-existing crack are generated by tension (i.e. mode-I cracks). As the confining pressure increases, the area of the mode-II cracks increases, while the area of the mode-I ones decreases.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110943"},"PeriodicalIF":4.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143509605","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":"Determination of fracture toughness of concrete based on actual critical crack length: Theoretical model and experimental validation","authors":"Hongwei Wang ,&nbsp;Mengdi Jia ,&nbsp;Xingyu Yang ,&nbsp;Yanjie Wang ,&nbsp;Rena C. Yu ,&nbsp;Zhimin Wu","doi":"10.1016/j.engfracmech.2025.110966","DOIUrl":"10.1016/j.engfracmech.2025.110966","url":null,"abstract":"<div><div>The fracture toughness of concrete is a critical parameter for the evaluation of the stability of cracks and the subsequent safety of structures. However, the parameter is typically underestimated when it is calculated by substituting the effective critical crack length into linear elastic fracture mechanics formulas, thereby impeding the ability to conduct a reasonable assessment of the safety of structures. In light of the above, this study develops a theoretical model for determining the fracture toughness of concrete based on the actual critical crack length. Firstly, the theoretical foundation for the model is elucidated, and governing equations are formulated based on the competition mechanism of the crack propagation resistance and the driving force. These equations can be used to solve the peak load, actual critical crack length, and fracture toughness. Subsequently, to verify the effectiveness of the model, fracture tests of wedge splitting specimens are performed, and the actual critical crack length is captured using the digital image correlation method. The fracture toughness calculated with the proposed model is then compared with the results measured by the authors and collected form the literature. The findings demonstrate that the fracture toughness calculated using the proposed model correlates well with experimental outcomes. Therefore, it can be concluded that the proposed model can be applied to predict the fracture toughness of concrete when the requisite material parameters, including the tensile strength, fracture energy, Young’s modulus, and initial fracture toughness, are provided. This model offers the advantage of considering the actual critical crack length, which would be difficult to measure directly due to the higher demands on the test equipment. It is anticipated that the investigation will facilitate a comprehensive insight into the fracture mechanism of concrete and an accurate estimation of the mechanical performance of concrete structures.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110966"},"PeriodicalIF":4.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143520515","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 investigation of rock mechanics behavior under multistage pulsating load based on digital image correlation and acoustic emission technology","authors":"Huaidong Liu,&nbsp;Changyou Liu,&nbsp;Fengfeng Wu,&nbsp;Zhenhua Chen,&nbsp;Xin Yu,&nbsp;Jingxuan Yang","doi":"10.1016/j.engfracmech.2025.110984","DOIUrl":"10.1016/j.engfracmech.2025.110984","url":null,"abstract":"<div><div>Pulsating loading effectively reduces rock strength and improves rock-breaking efficiency. To reveal the influence mechanism of pulsating parameters on rock mechanical properties, this study conducted a series of pulsating loading tests on sandstone specimens with varying frequencies and stress amplitudes. Results show that low frequency and medium stress amplitude are most favorable for strength and deformation resistance reduction. Pulsating load weakens rock strength primarily by reducing inter-particle cohesion and friction. Lower frequencies correlate with higher acoustic emission (AE) counts and greater rock damage. Under medium stress amplitude, AE <em>b</em>-value fluctuations last longest, with earliest failure precursors. As pulsating frequency and stress amplitude increase, damage transitions from overall to localized, and from gradual to instantaneous. Dissipated energy reflecting crack propagation resistance decreases with lower frequencies, while elastic energy driving crack extension increases with higher amplitudes. When pulsating frequency and stress amplitude are elevated, one-dimensional damage indices fail to accurately reflect local damage concentration in the rock. However, two-dimensional and three-dimensional damage indexes from digital image correlation and AE cumulative counting effectively characterize rock damage progression. This study elucidates the mechanisms by which pulsating loads influence the mechanical behavior of rocks, providing insights for the optimization of rock-breaking techniques in various applications.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110984"},"PeriodicalIF":4.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143527173","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":"Analysis of the distributed laser-assisted rock breaking mechanism by TBM disc cutters – based on microscopic scale scratch tests and macroscopic scale scaled-down disc cutter indenter penetration tests","authors":"Kui Zhang ,&nbsp;Shangjun Xiao ,&nbsp;Wangwang Liu ,&nbsp;Dinghua Wang ,&nbsp;Gaofeng Zhang ,&nbsp;Jiawei Sun","doi":"10.1016/j.engfracmech.2025.110940","DOIUrl":"10.1016/j.engfracmech.2025.110940","url":null,"abstract":"<div><div>The energy density of traditional straight round laser (SL) is overly concentrated, easily producing vitreous glaze, which severely affects the cutting performance of TBM cutters and the efficiency of laser utilization. This paper aimed to optimize the laser power density distribution by improving the beam shaping principle of existing SL. Firstly, a distributed laser (DL) model and a quick-detachable optical lens assembly design scheme were proposed, and their feasibility was verified through simulations. Furthermore, a DL rock-breaking experimental platform was constructed based on the E1309M laser cutting machine. Through friction probe scribing and scratch tests and scaled cutter indenter penetration tests, the effects of DL on the micro-physical and mechanical properties of rock and the macro cutting performance of cutters were studied. Finally, combining existing literature, the mechanism of laser-assisted cutter rock breaking was revealed. The results show that the inner focused beam of DL efficiently pre-forms cutting grooves, while the outer dispersed beam reduces heat accumulation, inhibiting the formation of vitreous glaze and enhancing the rock-breaking effect. The thermal impact zone generated by DL not only increases rock fracture toughness but also reduces rock-breaking energy consumption and the number of cutters required.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110940"},"PeriodicalIF":4.7,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487538","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":"Evaluating diversion effectiveness in a non-local elasticity based PKN fracturing model","authors":"Bo Luo,&nbsp;George K. Wong","doi":"10.1016/j.engfracmech.2025.110938","DOIUrl":"10.1016/j.engfracmech.2025.110938","url":null,"abstract":"<div><div>Enhancing production in unconventional reservoirs often relies on multi-stage fracturing in horizontal wells. Leveraging solid diverter particles can significantly improve cluster stimulation efficiency by promoting uniform fracture growth. However, the complex interactions between rock deformation, fluid dynamics, and particle transport in this process are not well understood. This study presents an integrated fracturing model that incorporates particle transport to evaluate and provide insights into the effectiveness of diversion techniques.</div><div>The study focuses on PKN-type fractures as a foundational model for unconventional reservoirs with height containment. To calculate stress interactions among fractures, we apply a non-local elasticity relationship that considers fracture width variation in height direction. To reduce computational complexity, we assume an elliptical fracture cross-section, simplifying double integrals to single integrals for non-local elasticity. Additionally, we use fracture height-averaged parameters to represent two-dimensional fluid flow within fractures as a one-dimensional model. The global tip asymptotic solution enhances computational efficiency by using a relatively coarse mesh to locate fracture fronts. The particle transport model employs the ‘wind’ scheme to track nonlinear particle waves and the Kozeny-Carman model to assess the permeability of the diverter pack. By treating the dispersed phase as a continuum, the coupled fracturing and particle transport model supports field-scale modeling of diversion techniques.</div><div>The proposed model is validated against analytical solutions for single-fracture scenarios and numerical solutions for multiple parallel and non-parallel fractures, as well as particle transport in single fracture. The model is then applied to examine diversion effectiveness in a numerical example involving three equally spaced clusters propagating in a transitional regime. The evaluation reveals that in PKN-type fractures with low stiffness and minimal stress interference, the expected stable and low-permeability diverter packs are not established inside overgrown fractures. Introducing swellable diverter particles enhances the effectiveness of diversion technology, enabling successful fluid diversion. The proposed model accommodates various propagation regimes, fracture stiffness levels, and slurry pumping schedules, providing insights for optimizing diversion techniques to improve cluster stimulation efficiency in unconventional reservoirs.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"319 ","pages":"Article 110938"},"PeriodicalIF":4.7,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143563602","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":"Using SCB specimens to quantify nonlinear fracture characteristics in concrete and rock materials","authors":"Ragip Ince","doi":"10.1016/j.engfracmech.2025.110951","DOIUrl":"10.1016/j.engfracmech.2025.110951","url":null,"abstract":"<div><div>The normalized stress intensity factors for semi-circular bending (SCB) specimens have only been derived up to now. Therefore, experimental investigations on SCB specimens have been limited in terms of concrete fracture. In this study, the important linear elastic fracture mechanics formulas for SCB specimens are initially derived using the finite element method to evaluate the stable and unstable crack growth states of cracked quasi-brittle structures. Cement-based SCB specimens and beams are produced in two sets (concrete and mortar) and subjected to bending tests. The test results of the aforesaid specimens are compared according to three popular fracture approaches in concrete fracture: the two-parameter model, the size effect model, and the double-K model. It is concluded that there is a strong correlation between the fracture toughness of beams and SCB specimens for each set. Based on this agreement, three series of SCB rock experiments in the literature are subsequently examined using the aforesaid concrete fracture models. The results of this investigation illustrate that nonlinear fracture characteristics of rock and concrete materials can easily be estimated by employing single-sized SCB specimens.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110951"},"PeriodicalIF":4.7,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487448","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 study on fracture mechanism of quartz crystal under impact crushing","authors":"Junquan Lai ,&nbsp;Ningning Liao ,&nbsp;Caibin Wu ,&nbsp;Huiming Sheng ,&nbsp;Quan Li ,&nbsp;Ziyu Zhou ,&nbsp;Liangwei Li","doi":"10.1016/j.engfracmech.2025.110945","DOIUrl":"10.1016/j.engfracmech.2025.110945","url":null,"abstract":"<div><div>The majority of naturally occurring ores consist of crystalline structures. Understanding the fracture behavior of crystals during ore crushing is critical for comprehending the mechanical properties of ores. This study investigates the fracture behavior of quartz crystals under impact crushing conditions. The findings reveal a strong correlation between the mechanical properties of quartz particles and their fracture behavior. At low specific energy of impact crushing (E_cs), the fracture mode of quartz grains is predominantly intergranular. With increasing E_cs, the fracture mode transitions from intergranular to transgranular. During fracture, deformation initiates preferentially in coarse grains, while the proportion of fine grains undergoing deformation increases with E_cs. The results suggest that grain boundary strength and the proportion of fine grains are critical factors influencing the mechanical properties of ores. The study also finds that when subjected to external forces, variations in deformation capacity among grains result in uneven deformation during fracture. The activation of the {0001} &lt; 11–20 &gt; and {10–10} &lt; 11–20 &gt; slip systems promotes plastic deformation in quartz crystals, whereas activation of the {10–11} &lt; 11–20 &gt; slip system hinders plastic deformation in fine grains. Differences in grain deformation capacity during fracture introduce uncertainty in the fracture behavior and crack propagation of quartz grains, elucidating the mechanisms behind the specific particle size distribution observed post-fracture.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110945"},"PeriodicalIF":4.7,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143478607","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":"Adhesive bond characterization under mixed-mode I + II loading using the mmb test","authors":"Ainhoa Arrese ,&nbsp;Faustino Mujika ,&nbsp;Jordi Renart ,&nbsp;Carlos Sarrado","doi":"10.1016/j.engfracmech.2025.110962","DOIUrl":"10.1016/j.engfracmech.2025.110962","url":null,"abstract":"<div><div>This study presents an experimental method to determine mixed mode cohesive law of adhesive joints in mixed mode.</div><div>In the proposed method, based on the Mixed Mode Bending test, the <em>J-</em>integral and crack tip relative displacements are determined based on an equivalent crack length method by processing the global load–displacement curve, without monitoring the crack length, the bending rotations at the loading points and the crack tip relative displacement during the test.</div><div>The precision of the method is validated experimentally comparing the results obtained by the proposed methods with those obtained by the Direct Method, where the fracture toughness is determined based on the rotations of the load introduction points and the crack tip displacement is directly measured.</div><div>Results reveal that the proposed data reduction scheme is suitable to obtain the mixed mode characterization of an adhesive joint monitoring only the load–displacement curve, without any external displacement measurement technique and without any assumption of the form of the cohesive law.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110962"},"PeriodicalIF":4.7,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143528793","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 fracture behavior of a novel multi-scale fiber reinforced ultra-high performance concrete with hollow microspheres after high temperatures","authors":"Yao Zhang ,&nbsp;Pan Feng ,&nbsp;Shaoqi Zhang ,&nbsp;Weigang Zhao ,&nbsp;Zhiguo Yan ,&nbsp;Hehua Zhu ,&nbsp;J.Woody Ju","doi":"10.1016/j.engfracmech.2025.110979","DOIUrl":"10.1016/j.engfracmech.2025.110979","url":null,"abstract":"<div><div>In this paper, a novel multi-scale fiber reinforced ultra-high performance concrete (MSFUHPC) reinforced with polyethylene (PE) fibers, steel fibers, and carbon fibers mixed with lightweight aggregates is developed to obtain high strength and high toughness. The fracture behavior of MSFUHPC after exposure to elevated temperatures is critical to understanding the structural behavior of engineering structures in a fire accident. Therefore, the effects of multi-scale fibers, fly ash cenospheres (FAC), and hollow alumina microspheres (HAM) on the fracture properties of MSFUHPC are investigated. Results reveal that multi-scale fibers can significantly enhance the fracture toughness of UHPC by restraining crack propagation. Incorporating hollow microspheres increases the number of microcracks around the main crack, which prolongs the unstable crack propagation stage and improve the deformation capacity, as a result of which the unstable fracture toughness and the total fracture energy can be strengthened. Moreover, the fracture toughness and fracture energy of the specimen gradually decrease as the temperature increases from 25 °C to 600 °C due to the weakened bonding effect of the fibers with the matrix and the deteriorated microsphere-matrix ITZ. After 400 °C, the specimens mixed with FAC can maintain a relatively high ductility index because of the good bonding between FAC and the matrix. After 600 °C, the fracture energy of MSFUHPC decreases by about 82.3 %-92.1 %, mainly thanks to the thermo-damaged bridging capability of the steel and carbon fibers.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110979"},"PeriodicalIF":4.7,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143509607","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 study of the effect of splits on specimen compliance and Δa results","authors":"Sergio Luis Gonzalez Assias ,&nbsp;Hector Guillermo Kotik ,&nbsp;Juan Elías Perez Ipiña ,&nbsp;Marcelo Paredes","doi":"10.1016/j.engfracmech.2025.110970","DOIUrl":"10.1016/j.engfracmech.2025.110970","url":null,"abstract":"<div><div>Fracture toughness testing of materials with delaminations perpendicular to the main crack (splits) is complex due to unclear effects on specimen compliance. This study examines how split morphology influences compliance and crack extension measurements using the unloading compliance method. Experiments on DH36 and X70 steels, combined with numerical simulations, CT scans, SEM, and confocal microscopy, revealed that splits within the thickness (TL) plane have negligible impact on compliance. However, deviations from the TL plane significantly increase compliance, leading to crack growth in <em>J-R</em> curves. These findings contradict existing compliance hypotheses for split specimens.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110970"},"PeriodicalIF":4.7,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474333","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}