Theoretical and Applied Fracture Mechanics最新文献

{"title":"Using fractal voids to understand Mode I compressive fracture in brittle materials – A two-dimensional analysis","authors":"","doi":"10.1016/j.tafmec.2024.104648","DOIUrl":"10.1016/j.tafmec.2024.104648","url":null,"abstract":"<div><p>Unlike cases of direct or indirect tensile loading, analysis of Mode I fracture in cases of compressive loading must necessarily consider two-dimensional flaw geometries. The consequent analytical complications have resulted in little theoretical evolution towards understanding Mode I fracture in compressive loading. Researchers have recently observed that the linear elastic (LE) stress fields surrounding two-dimensional flaws in compression appear to have indicative value regarding Mode I fracture, but no rational framework has yet been proposed for their interpretation. Herein it is demonstrated that by idealizing void surfaces as fractal, and using what will be called the “small flaw assumption,” LE stress fields can be interpreted to obtain significant insight regarding brittle Mode I compressive fracture. Using fractal voids, a rational and consistent explanation for the satisfaction of the stress and energy criteria at the surface of two-dimensional flaws is presented. The discussion resolves many typical theoretical issues in the literature in a manner consistent with fundamental Griffith theory, and accounts for size and shape effects. The framework further enables the computationally efficient prediction of peak K_I values associated with the propagation of line cracks from two-dimensional flaws from a brittle medium subject to macroscopic uniaxial compression via LE stress fields.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142148032","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 investigations on rate-dependent fracture behavior of concrete-rock interface","authors":"","doi":"10.1016/j.tafmec.2024.104646","DOIUrl":"10.1016/j.tafmec.2024.104646","url":null,"abstract":"<div><p>To ensure the safety and stability of the concrete gravity dams built in the seismic regions, this study investigated the rate-dependent fracture behavior of the concrete-rock interfaces with different roughness degrees. Firstly, direct tensile tests and three-point bending tests were conducted to measure the mechanical and fracture properties of the concrete-rock interface with three roughness degrees, i.e. the 4 × 4 interface, natural interface, and 7 × 7 interface, and under four strain rates, i.e. 10^-5/s, 10^-4/s, 10^-3/s, and 10^-2/s. By employing the fictitious crack model and initial fracture toughness-based crack propagation criterion, numerical simulations were conducted to analyze the crack propagation processes of the concrete-rock interfaces under different strain rates. The results indicated that the tensile strength and initial fracture toughness exhibited an obvious increasing tendency with the increase of the strain rates, and they showed a nearly linear relationship with the logarithms of the strain rates. Prediction models were proposed to calculate the tensile strength and initial fracture toughness of the concrete-rock interface under different strain rates. In addition, the initial fracture toughness-based crack propagation criterion was proved to be applicable to analyze the crack propagation processes of the concrete-rock interfaces under both quasi-static and seismic strain rates. It was found that the fully-formed fracture process zone lengths and the corresponding crack length decreased obviously with the increase of the strain rates, indicating that the boundary effect of the concrete became stronger under the higher strain rates, which approached to the fracture behaviors of the large-size specimens.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142148030","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":"Corrigendum to “Solution of a Dugdale–Barenblatt crack in an infinite strip by a hyper-singular integral equation” [Theor Appl. Fract. Mech. 133(Part B) (2024) 104625]","authors":"","doi":"10.1016/j.tafmec.2024.104645","DOIUrl":"10.1016/j.tafmec.2024.104645","url":null,"abstract":"","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0167844224003951/pdfft?md5=17fa266f7c6ab4fb9c233f41548471c4&pid=1-s2.0-S0167844224003951-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163835","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":"Image-based learning and experimental verification of crack propagation in random multi-fractures rock","authors":"","doi":"10.1016/j.tafmec.2024.104640","DOIUrl":"10.1016/j.tafmec.2024.104640","url":null,"abstract":"<div><p>Fractures and the rock matrix are fundamental components of rock masses, with their random distribution being a common characteristic. Previous studies often focus on regularly fractured rock samples to facilitate experimental and numerical analysis. However, the limited number of samples used in these studies hinders a comprehensive understanding of the mechanical properties and failure characteristics of fractured rock masses. In this paper, we implement batch numerical simulations using PFC (Particle Flow Code) with an original automatic control code, resulting in a dataset of 400 numerical simulation results. The crack propagation characteristics and failure parameters of rock mass with random multi-fractures have been studied by using GANs (Generative Adversarial Networks) and other neural network models. Randomly fractured granite samples were subjected to uniaxial compression loadings, and the evolution of the strain field was analyzed by applying digital image processing technology. The testing results were then compared with the training model results. After verifying the model’s accuracy, the obtained CNN (Convolutional Neural Networks) model can be used to predict the UCS (Uniaxial Compressive Strength) of the real experimental samples. Additionally, we analyzed and discussed the influence of various parameters of random fractured rock mass on its bearing capacity.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142136830","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":"Sparse polynomial chaos expansion and adaptive mesh refinement for enhanced fracture prediction using phase-field method","authors":"","doi":"10.1016/j.tafmec.2024.104639","DOIUrl":"10.1016/j.tafmec.2024.104639","url":null,"abstract":"<div><p>Phase-field models (PFMs) have proven to accurately predict complex crack patterns such as crack branching, merging, and crack fragmentation, but they are computationally costly. This study stems from the high computational costs associated with non-adaptive PFMs for brittle fracture analysis, which require dense meshes. This makes training data generation for surrogate models prohibitively expensive. To address these challenges, this paper proposes an adaptive mesh refinement (AMR) informed sparse polynomial chaos expansion (PCE) framework. The AMR algorithm is incorporated into the fracture analysis workflow to maximize the computational efficiency in data generation, eliminating the need for pre-refinement. The AMR informed sparse PCE is calibrated with Bayesian compressive sensing (BCS) to efficiently map domain input parameters to quantities of interest (QoIs), even with limited training data. We employ a multi-output QoI approach to predict load–displacement relationships with high resolution. The novelty of this work lies in the integration of AMR into the PFM workflow and the application of sparse PCE for brittle fracture analysis. Benchmark tests demonstrate the proposed method’s superior accuracy and computational efficiency compared to conventional AMR method, marking a notable improvement in fracture mechanics.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122253","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 estimation of complex stress intensity factor for the completely debonded anti-crack embedded into a weak matrix using domain integral method","authors":"","doi":"10.1016/j.tafmec.2024.104642","DOIUrl":"10.1016/j.tafmec.2024.104642","url":null,"abstract":"<div><p>The problem of interface debonding is of fundamental importance in understanding the stress transfer mechanism and behavior of weak interfaces present due to rigid stiffeners. A domain integral method based on Betti’s reciprocal theorem was adopted to compute the complex stress intensity factor (SIF) for the completely debonded anti-crack (discontinuity) with mixed boundary conditions. The domain integral approach is based on two admissible mechanical states, which comprise of actual and auxiliary elastic fields. The singular auxiliary fields in terms of angular variations for the completely debonded anticrack were obtained using the full-field solution. The obtained angular variations were compared with the Williams eigenvalue problem for completeness. The displacement and strains were obtained using digital image correlation (DIC) experiments and numerical simulation for parallel and perpendicular orientations of the discontinuity. The obtained DIC strain contours revealed the presence of anti-symmetric and symmetric variation on the bonded side of the anti-crack. The complex SIF is estimated experimentally and numerically based on the domain integral method to seek a better comparison with the analytical estimate. The SIF estimated for the perpendicular orientation is higher than the parallel orientation.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142148029","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":"Assessment of fracture toughness in fibrous concrete via Brazilian test: Experimental study with low-clinker cementitious binder","authors":"","doi":"10.1016/j.tafmec.2024.104641","DOIUrl":"10.1016/j.tafmec.2024.104641","url":null,"abstract":"<div><p>As the predominant and cost-effective material in the construction industry, concrete is susceptible to tension weaknesses, leading to significant flaws such as cracking and brittle fracturing. Recent advancements in fibrous concrete have emerged as a solution to mitigate these issues. Incorporating steel fibers in concrete has emerged as a promising solution to improve crack resistance and structural integrity. This study focuses on developing eco-friendly concrete using a low-clinker cementitious binder and short steel fibers to enhance fracture toughness and mitigate the environmental impact by effectively utilizing lime sludge. Concrete specimens were prepared with three binder types: treated lime sludge (TLS) at 15 % and 30 % and calcined clay (CC) at 15 % and 30 %, replacing conventional clinker. Short steel fibers were added at 1.5 % by volume to enhance mechanical properties. Fracture toughness was evaluated using notched Brazilian disc specimens, assessing mode I, II, and mixed-mode (I/II) fracture at multiple notch orientations (β = 0°, 15°, 28.83°, 45°, 60°, 75°, and 90°). Microstructural analysis during strength development was performed using scanning electron microscopy and X-ray diffraction. The findings revealed that specimens containing 15 % TLS, 30 % CC, and 1.5 % steel fibers exhibited the highest fracture toughness. Mode II fracture toughness exceeded mode I, indicating improved resistance to crack propagation. The addition of fibers to the specimens under mode II demonstrated improved fracture toughness, ranging from 0.44 to 0.53 MPa·m^{^1/2} compared to the corresponding non-fibrous specimens. The fibrous specimens showed significantly higher ultimate loads at β = 90° compared to β = 0°, indicating superior crack resistance and structural integrity under perpendicular loading conditions. The Brazilian disc specimens demonstrated variability in fracture toughness across different loading orientations, highlighting their suitability for mixed-mode fracture assessment.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142099477","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":"Numerical characterization on fracture evolution behavior of pre-flawed sandstone under monotonic and multilevel cyclic loading","authors":"","doi":"10.1016/j.tafmec.2024.104634","DOIUrl":"10.1016/j.tafmec.2024.104634","url":null,"abstract":"<div><p>This study employed an improved stress corrosion model within a three-dimensional particle flow program to investigate the mechanical and cracking behavior of fractured sandstone samples with varying rock bridge angles under both monotonic loading and multilevel cyclic loading. Firstly, using the experimental results from intact sandstone under uniaxial compression, we calibrated the microscopic mechanical parameters of the parallel bond model. Then, the model was validated using the experimental results of fractured sandstone under monotonic and cyclic loading. Finally, the initiation, propagation, and coalescence behavior of cracks in fractured sandstone samples under the above two loading paths, as well as the evolution process of the stress field, displacement field, and force chain distribution, were discussed in detail. The results show that the stress–strain curves, strength, deformation parameters, and macroscopic failure modes obtained from numerical simulations are consistent with those from laboratory mechanical tests. The mechanical behavior of fractured sandstone is influenced by both the rock bridge angle and the loading path. As the rock bridge angle decreases, the mechanical parameters of the sample show an increasing trend, and the influence of rock bridge angle on the failure mode is reduced. Cracks in the samples all initiate at the tips of pre-existing flaws, and the rock bridge angle affects the crack propagation and coalescence process: for sandstones with smaller rock bridge angles, cracks gradually extend to the sample’s ends; for sandstones with larger rock bridge angles, direct coalescence of cracks at the rock bridge is observed, then extending to the sample’s ends. Compared with monotonic loading, the damage degree of sandstone samples under multilevel cyclic loading is more severe, and even obvious block spalling is observed. The experimental and numerical simulation results are expected to improve the understanding of the mechanical behavior and fracture behavior of fractured rocks under monotonic and multilevel cyclic loading.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142088969","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":"Fracture properties and acoustic emission characteristics of manufactured sand recycled fine aggregate concrete","authors":"","doi":"10.1016/j.tafmec.2024.104633","DOIUrl":"10.1016/j.tafmec.2024.104633","url":null,"abstract":"<div><p>To promote the application of recycled fine aggregates, fracture characteristics of concrete beams containing manufactured sand (MS) and recycled fine aggregate (RFA) were investigated. The fracture properties and acoustic emission (AE) characteristics of manufactured sand recycled fine aggregate concrete (MSRFAC) with 0 %, 25 %, 50 %, 75 % and 100 % RFA replacement rates were evaluated by three-point bending test of single-sided notched beams. The fracture mechanisms of MSRFAC beams were explored using AE and digital image correlation (DIC) techniques, and fracture process zone (FPZ) was qualitatively and quantitatively analyzed. The results indicated that the critical nominal stiffness, initial fracture toughness, fracture energy and characteristic length of MSRFAC decreased significantly with the increase of RFA replacement rate, up to 20.2 %, 37.7 %, 22.8 %, and 26.6 %, respectively, while the unstable fracture toughness was insensitive to the variation of RFA. Moreover, the AE activity, the tensile crack, large-scale crack, high amplitude, and high peak frequency in MSRFAC increased with increasing RFA replacement rate. According to the FPZ characteristics of MSRFAC, its FPZ length increased with the increase of RFA replacement rate, while the FPZ width decreased with the increase of RFA replacement rate. The critical FPZ lengths of MSRFAC with different RFA replacement rates were about 20.2–30.0 mm, and the maximum FPZ widths were about 26.0–36.7 mm. The RFA weakened the friction mechanism and interlocking effect between aggregates of MSRFAC, resulting in a faster FPZ propagation rate and smaller damage width of MSRFAC than normal manufactured sand concrete.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142083391","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 properties of sandstone with two circular inclusions under impact loading","authors":"","doi":"10.1016/j.tafmec.2024.104636","DOIUrl":"10.1016/j.tafmec.2024.104636","url":null,"abstract":"<div><p>Inclusions are often present in rock defects, which can compensate for some of the problems of low rock strength and poor stability caused by hole defects. Specimens containing inclusions exhibit different mechanical properties under dynamic loading, and the strength change, energy evolution law and fracture mechanism deserve to be clearly discussed. In this work, a dynamic impact test of sandstone with circular inclusions was carried out. The failure process of each sample was recorded by a high-speed camera, and the influences of the inclusion strength and strain rate on the dynamic impact performance of the sandstone were analysed. Increasing the strain rate and inclusion strength can significantly improve the dynamic compressive strength of a sample. The dissipated energy density and impact toughness index are positively correlated with the strain rate. The dissipated energy density increased the most when the sample type was FA, at 10.6%. When the sample type was FD, the impact toughness index increased the most, which was 49.1%. In the early stage of loading, the localized strain is mainly concentrated inside the filler and gradually evolves into deformation of the filler and extension of shear cracks in the late stage of loading. The failure modes of a sample are not the result of a single factor but are influenced by both the strain rate and the filler. The types of cracks in the samples are mainly shear cracks and shear–tension composite cracks.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142083222","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}