Engineering Fracture Mechanics最新文献

{"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}

{"title":"A comparison between FEM predictions and DIC results of crack tip displacement field in AA2024-T3 CT specimens","authors":"E.R. Sérgio ,&nbsp;G.L. Gómez Gonzáles ,&nbsp;J.M. Vasco-Olmo ,&nbsp;F.V. Antunes ,&nbsp;P. Prates ,&nbsp;F.A. Díaz ,&nbsp;D.M. Neto","doi":"10.1016/j.engfracmech.2025.110964","DOIUrl":"10.1016/j.engfracmech.2025.110964","url":null,"abstract":"<div><div>In the current paper, fatigue crack growth is modelled using a node-release strategy based on crack tip plastic deformation. The accuracy of material elastic–plastic modeling is crucial for the quality of the numerical predictions. Stress–strain loops obtained in low cycle fatigue (LCF) were used to fit material constants for 2024-T3 aluminium alloy, which is the procedure usually followed. The material model was validated with Digital Image Correlation (DIC), with results obtained at different distances behind the crack tip in a thin CT specimen. Significant differences were found between FEM predictions and experimental results for plastic COD, which were attributed to an inadequate elastic–plastic model. In fact, the LCF tests always have small strain ranges, much smaller than the observed at the crack tip. The change of the isotropic hardening law from Swift to Voce improved the predicted plastic COD values. The final conclusion is that the fitting of the material parameters using LCF results must be validated with DIC-FEM comparisons for the case of thin specimens.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110964"},"PeriodicalIF":4.7,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464920","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}

{"title":"Machine learning approaches for predicting rock mode I fracture toughness: Insights from ISRM suggested CCNBD and SCB tests","authors":"Yuezong Yang ,&nbsp;Zhushan Shao ,&nbsp;Kui Wu ,&nbsp;Nannan Zhao ,&nbsp;Yujie Wang","doi":"10.1016/j.engfracmech.2025.110949","DOIUrl":"10.1016/j.engfracmech.2025.110949","url":null,"abstract":"<div><div>Mode I fracture represents a prevalent failure mechanism in rocks, attributed to the typically significantly lower tensile strength compared to their shear strength. The cracked chevron notched Brazilian disc (CCNBD) and semi-circular bend (SCB) tests are two techniques recommended by the International Society for Rock Mechanics (ISRM) for assessing mode I fracture toughness and are commonly employed in laboratory research. The fracture toughness of a rock specimen depends on its geometric dimensions and mechanical properties. Clarifying the geometric size impacts of various types of rocks in mode I fracture toughness testing is both costly and time-consuming. Machine learning offers a predictive approach for determining the fracture toughness of rocks. This investigation leverages six sophisticated machine learning models, encompassing decision regression tree (DRT), random regression forest (RRF), generalized regression neural network (GRNN), gaussian process regression (GPR), support vector machine (SVM) and generalized additive model (GAM), to forecast the mode I fracture toughness within the CCNBD and SCB testing paradigms. The variance in input variables between the two tests is attributed to the distinct geometrical attributes of the CCNBD and SCB specimens. Tensile strength, specimen radius, specimen thickness and three dimensionless parameters related to the initial and final cracked chevron notch lengths and specimen thickness are the input variables for CCNBD tests. Tensile strength, specimen radius, specimen thickness, notch length and the span of the two loading cylindrical rollers are input variables for SCB tests. Five evaluation indicators of machine learning models, i.e., mean absolute error, mean absolute percentage error, mean square error, root mean square error and coefficient of determination, are adopted to comprehensively evaluate the predictive performance of these models. According to the evaluative metrics, the DRT and GPR models emerge as the most effective for CCNBD and SCB tests, respectively. The significance of input variables for the prediction of mode I fracture toughness was delineated employing Shapley additive explanations. The findings underscore the paramount influence of tensile strength on mode I fracture toughness within both CCNBD and SCB testing methodologies. Considering the influences of sample value differences in CCNBD and SCB datasets and taking mean absolute percentage error and coefficient of determination as the evaluation indicators, the machine learning models are more suitable in predicting mode I fracture toughness in CCNBD tests than that in SCB tests. This study delivers valuable insights for the prediction of mode I fracture toughness in rocks via machine learning techniques.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110949"},"PeriodicalIF":4.7,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143478608","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 mesoscopic fracture process and weakening mechanism of water on rockbursts","authors":"Jie Sun ,&nbsp;Kai Ling ,&nbsp;Shudong Zhang ,&nbsp;Dongqiao Liu","doi":"10.1016/j.engfracmech.2025.110950","DOIUrl":"10.1016/j.engfracmech.2025.110950","url":null,"abstract":"<div><div>Rockbursts induced by quasidynamic loads in deeply buried tunnels are highly susceptible to water and pose a critical engineering challenge. This study designs sandstone specimens with circular openings with various saturation levels to investigate the effects of water on rockbursts. Subsequently, rockbursts are triggered by quasi-dynamic loads in the true-triaxial loading state. The rockburst fracture process under different saturation levels and the fracture mode of the sidewall of the circular opening are analyzed using a microporous photography system and an acoustic emission (AE) monitoring system. The results indicate that water has a vital effect on the rockburst behavior of sandstone. Water had a dual effect on the fracture process of the sidewall during rockbursts, revealing a promoting effect on the tensile fracture before rockburst at lower saturation levels; however, a driving effect for shear fractures was observed when the saturation level exceeded 50%. The dual mechanisms of the fluid wedge and lubrication effects are considered critical factors in transforming the sidewall fracture mechanism before the rockbursts occur. However, water accelerates the macroscopic damage before the rockburst, but weakens the overall strength of the rockburst. The calculation results based on the particle image velocimetry (PIV) method showed that when the saturation level increased from 0% to 100%, the rockburst intensity decreased from moderate to slight. Finally, two mechanisms are summarized to explain the weakening effect of water on the severity of rockbursts: (i) the weakening effect of water on the ultimate energy storage capacity of sandstone units, leading to a decrease in the dynamic behavior of the initial failure; (ii) the increasing effect of water on plastic deformation enhanced the sustained energy dissipation behavior of sandstone units rather than promoting energy accumulation. This effect led to a decrease in the residual excess energy of sandstone under dynamic loads.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"318 ","pages":"Article 110950"},"PeriodicalIF":4.7,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487447","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}