Theoretical and Applied Fracture Mechanics最新文献

{"title":"Machine learning-assisted fracture toughness prediction in FFF-printed carbon fibre-reinforced ASA composites: A multi-model approach with time-series feature engineering and physics-informed regularisation","authors":"Ümit Yılmaz","doi":"10.1016/j.tafmec.2026.105904","DOIUrl":"10.1016/j.tafmec.2026.105904","url":null,"abstract":"<div><div>Fused filament fabrication (FFF) of short carbon fibre-reinforced acrylonitrile–styrene–acrylate (ASA-CF) composites produces process-induced anisotropy from raster orientation, void formation, and interlayer bond variability. Classical analytical fracture models, including the Theory of Critical Distances (TCD), establish reliable group-mean fracture load estimates but cannot resolve specimen-level scatter governing component reliability. This study presents an end-to-end machine learning pipeline to predict apparent fracture toughness (<span><math><msub><mi>K</mi><mi>Ic</mi></msub></math></span>), fracture energy (<span><math><msub><mi>U</mi><mi>f</mi></msub></math></span>), and peak load (<span><math><msub><mi>F</mi><mi>max</mi></msub></math></span>) from 72 single-edge-notch bending (SENB) specimens spanning three raster orientations and four notch radii. Load–displacement curves were encoded into approximately 728 features using automated time-series extraction augmented with scalar geometric descriptors. Three supervised regression models, namely CatBoost, Extremely Randomised Trees, and Gaussian Process Regression (GPR), were optimised via nested five-fold cross-validation with Bayesian search. Wilcoxon signed-rank tests with Holm–Bonferroni correction revealed no statistically significant performance differences among models for any target (all <span><math><msub><mi>p</mi><mi>adj</mi></msub></math></span>&gt; 0.18). GPR achieved the highest accuracy for <span><math><msub><mi>U</mi><mi>f</mi></msub></math></span> (R² = 0.964 ± 0.114) and <span><math><msub><mi>F</mi><mi>max</mi></msub></math></span> (R² = 0.987 ± 0.013); CatBoost performed best for <span><math><msub><mi>K</mi><mi>Ic</mi></msub></math></span> (R² = 0.573 ± 0.059, RMSE = 0.128 MPa√m). The TCD baseline yielded R² = 0.181, confirming its limitation as a group-mean estimator. A physics-informed neural network constrained by TCD achieved R² = 0.708, identical to an MSE-only baseline, as the penalty remained completely inactive throughout training. SHAP analysis identified an FFT-derived load–displacement curve feature (Spearman <em>r</em> = −0.616) as the dominant <span><math><msub><mi>K</mi><mi>Ic</mi></msub></math></span> predictor, physically linked to crack-front interlayer interaction.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"147 ","pages":"Article 105904"},"PeriodicalIF":6.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148854131","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":"Geopolymer formulation and performance evaluation for reinforcing sandstone against mode II fracture","authors":"Xuelan Wang,&nbsp;Xuejiao Wei,&nbsp;Wenjie Wan,&nbsp;Haoyang Peng,&nbsp;Nan Mu,&nbsp;Chao Wang","doi":"10.1016/j.tafmec.2026.105901","DOIUrl":"10.1016/j.tafmec.2026.105901","url":null,"abstract":"<div><div>This study formulates and evaluates geopolymer grouts designed for reinforcing sandstone subjected to Mode II fracture. The compressive strength, tensile strength, and Mode II fracture toughness of intact red sandstone were first characterized as baseline references. Subsequently, ternary geopolymer matrices incorporating variable dosages of fly ash, ground granulated blast furnace slag (GGBS), and coal gangue were fabricated and systematically tested, with the water-to-binder ratio and sodium silicate modulus identified as critical regulating parameters. Among the tested formulations, the mixture with a fly ash:slag:coal gangue ratio of 3:5:2 achieved the optimal balance between mechanical strength and fracture resistance, and was accordingly selected for sandstone grouting repair, attaining a maximum uniaxial compressive strength of 60.6 MPa after 28 days of standard curing. Following geopolymer injection, the Mode II fracture toughness of the treated sandstone increased by approximately two-fold. A corresponding numerical model successfully reproduced the observed failure patterns. Microscopic characterizations via XRD and SEM revealed that dense continuous C-(A)-S-H gel and integrated rock-grout interfacial bonding constitute the dominant strengthening mechanism. In addition, an ABAQUS-Python integrated workflow was developed to reconstruct crack propagation behavior, validate experimental observations, elucidate reinforcement mechanisms, and enable early warning of instability. Meanwhile, a coupled energy-load triple-criterion was proposed to address the misjudgment drawback of single fracture indicators. Experimental results demonstrate that geopolymer grouting remarkably elevates the Mode II fracture resistance of damaged sandstone, which delivers a sustainable remediation route for rock engineering.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"147 ","pages":"Article 105901"},"PeriodicalIF":6.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148951172","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":"Fatigue of AM TiAl6V4: Benchmark of defect criticality models","authors":"Sebastian Mansky,&nbsp;Dirk Herzog,&nbsp;Ingomar Kelbassa","doi":"10.1016/j.tafmec.2026.105875","DOIUrl":"10.1016/j.tafmec.2026.105875","url":null,"abstract":"<div><div>Internal defects in laser powder bed fusion (PBF-LB/M) components are the primary drivers of fatigue failure, yet no systematic comparison of defect criticality models exists for ranking detected defects by severity. This work addresses two complementary research questions: (i) <em>which defect is most critical?</em> and (ii) <em>what fatigue-life does the critical defect imply?</em> For the first question, nine defect criticality ranking models, grouped into three geometry-based approaches (size ranking, Murakami <span><math><msqrt><mrow><mi>Area</mi></mrow></msqrt></math></span> model, Tammas-Williams model) and six simulation-based approaches (stress–strain concentration factor, averaged strain energy density, relative stress gradient, Smith–Watson–Topper parameter, equivalent plastic strain, Theory of Critical Distances), are benchmarked on two series of PBF-LB/M TiAl6V4 specimens (93 fatigue-tested; 84 of these inspected by X-ray CT prior to testing; 73 fractographically analysed after testing). The simulation-based models are evaluated with both a linear-elastic and an elastic–plastic material model. A matching procedure links CT defect data to fractographically identified fracture origins (21 of 84 CT-inspected specimens matched). For the second question, three crack growth models (Hartman-Schijve, Murakami–Endo, and a novel hybrid formulation) are compared for fatigue-life prediction based on the identified critical defect. Results show that geometry-based models achieve comparable ranking accuracy to computationally expensive simulation-based approaches, and that distinguishing between internal and surface crack growth environments is essential for accurate life prediction.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"147 ","pages":"Article 105875"},"PeriodicalIF":6.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148951299","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":"A fully coupled thermo-damage model for concrete cracking with two-way field interactions","authors":"Lahis Assis,&nbsp;Michèle Farage,&nbsp;Flávia Bastos","doi":"10.1016/j.tafmec.2026.105895","DOIUrl":"10.1016/j.tafmec.2026.105895","url":null,"abstract":"<div><div>This work presents the development and implementation of a fully coupled thermo-damage framework with two-way field interactions to simulate cracking in concrete structures subjected to mechanical, thermal, or combined loading. The cracking process is described using a discrete inter-element approach based on zero-thickness interface elements combined with a tensile damage law. The coupling between thermal and mechanical fields is addressed through multiple mechanisms. The influence of temperature on the mechanical response is incorporated via Free Thermal Strain (FTS), Load-Induced Thermal Strain (LITS), and temperature-dependent material properties. Conversely, the effect of cracking on heat transfer is considered through Crack Thermal Resistance (CTR), modeled as a damage-dependent reduction in thermal conductivity. A monolithic solution scheme is adopted, ensuring a consistent and simultaneous resolution of the multiphysics problem. The proposed framework is validated through several numerical examples, including comparisons with experimental and computational results available in the literature, showing good agreement and the ability to capture the main features of concrete behavior under elevated temperatures. A fully coupled analysis was also performed, highlighting the importance of bidirectional coupling in accurately representing thermomechanical responses. The results demonstrate that the proposed framework constitutes a consistent approach for simulating thermomechanical damage in concrete, emphasizing the relevance of explicitly accounting for two-way interactions between thermal and mechanical fields.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"147 ","pages":"Article 105895"},"PeriodicalIF":6.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148951298","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":"Crack propagation in composite rock mass and its influence on macro-mechanical properties under dynamic load","authors":"Feng Dai,&nbsp;Bozhao Dong,&nbsp;Longqiang Han,&nbsp;Min Ren,&nbsp;Chao Wang,&nbsp;Runlong Wan,&nbsp;Jiquan Ma,&nbsp;Yunfeng Wang,&nbsp;Zixuan Zhao","doi":"10.1016/j.tafmec.2026.105909","DOIUrl":"10.1016/j.tafmec.2026.105909","url":null,"abstract":"<div><div>Composite rock masses with distinct composite interfaces are ubiquitous in open-pit mining, tunnels, slopes, and foundation. They consist of alternating layers of different lithologies with prominent interfaces. Besides, tectonic movements often introduce joints and fissures, rendering them prone to sudden failure under dynamic disturbances. To investigate the propagation behavior of existing fissures and their effect on macroscopic mechanical properties under dynamic loading, composite rock specimens with different inclined fissure were prepared by two different strengths cement mortar mixes. Dynamic compression tests were performed on a split Hopkinson pressure bar (SHPB) system, and a high-speed camera captured real-time crack propagation and failure. Results show that specimens with 30° and 45° fissures exhibit interfacial shear failure: Cracks initiate at the low-strength material end or interface, while pre-existing fissure tips initiate as tensile cracks but transition to tensile-shear cracks upon reaching the composite interface due to shear stress concentration. In contrast, the 60° specimen fails in tensile opening mode, with cracks initiating from the pre-existing fissure tips and penetrating the specimen as tensile cracks. Analysis of strain and displacement contours reveals that as the fissure angle increases from 30° to 60°, the dominant failure factor shifts from the pre-existing fissure, to both the pre-existing fissure and composite interface, and finally to the composite interface. In additional, with increasing angle of fissure, the dynamic peak stress, dynamic elastic modulus, dissipated energy, and dissipation rate of composite rock undergoing first decrease and then increase, and reaching minima at 45°. Conversely, the reflection rate and fractal dimension of composite rock first increase and then decrease, peaking at 45°. These findings can provide a theoretical reference for stability analysis and safety protection in geotechnical engineering subjected to dynamic disturbances</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"147 ","pages":"Article 105909"},"PeriodicalIF":6.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148951300","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":"Investigating the underwater grouting effects on the mechanical properties and fracture evolutions of 3D-printed rock-like specimens with elliptical defects","authors":"Chuan Zhao,&nbsp;Zhengyu Zhu,&nbsp;Quan Zhang,&nbsp;Yifei Li,&nbsp;Junli Guo,&nbsp;Linlin Jiang,&nbsp;Xiang Xiao,&nbsp;Xin Zhang,&nbsp;Shuyang Yu","doi":"10.1016/j.tafmec.2026.105905","DOIUrl":"10.1016/j.tafmec.2026.105905","url":null,"abstract":"<div><div>This study investigates the grouting reinforcement mechanisms of rock masses containing elliptical defects through integrated experimental and numerical approaches. Sand-based 3D printing was used to prepare rock-like specimens with elliptical fissures of varying ellipticities and inclination angles, followed by underwater grouting. Uniaxial compression tests at a loading rate of 0.03 mm/min combined with Digital Image Correlation (DIC) enabled quantitative characterization of full-field strain evolution and crack propagation. A <em>meso</em>-scale PFC2D numerical model incorporating grout-rock interface bonding behavior was established to reproduce the progressive cracking process. Results show that ungrouted specimens exhibit a tensile-dominated failure mode with tensile cracks accounting for over 86% of all cracks, and crack evolution following a three-stage pattern. After grouting, the failure mode transforms into a composite form involving matrix tension and interface failure, with delayed crack initiation, enhanced post-peak continuity, significantly increased crack dispersion, and substantially higher total crack counts due to interface detachment. Grouting effectively eliminates stress discontinuity at the fissure cavity, reducing peak tip stress from 6.8 × 10⁴ Pa to approximately 1 × 10⁴ Pa, thereby weakening brittle instability risks. The strengthening effect varies with defect geometry, with near-circular holes showing the most significant improvement and intermediate ellipticities exhibiting the lowest strength enhancement. These findings provide a scientific basis for grouting reinforcement design and long-term stability assessment of irregularly fractured surrounding rock in deep underground engineering.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"147 ","pages":"Article 105905"},"PeriodicalIF":6.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148854128","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 moisture content on the size-dependent mode I fracture behavior of compacted clay","authors":"Xudong Li,&nbsp;Shiyuan Huang,&nbsp;Tianlong Zhao,&nbsp;Yu Xiao,&nbsp;Cheng Liao,&nbsp;Chuan Lv,&nbsp;Jing Xu","doi":"10.1016/j.tafmec.2026.105882","DOIUrl":"10.1016/j.tafmec.2026.105882","url":null,"abstract":"<div><div>Cracking in compacted clay cores is a potential hazard during the long-term service of earth-rock fill dams, and crack propagation may weaken the seepage control function of the core and threaten dam safety. The fracture resistance of compacted clay is sensitive to moisture content, while the size effect limits the direct extrapolation of laboratory fracture parameters to the engineering scale. To investigate how moisture content affects the size effect of Mode I fracture in compacted clay, three-point bending tests were conducted on notched deep beam (NDB) specimens with four specimen sizes and four moisture contents. Digital image correlation (DIC) was used to quantify the fracture process zone (FPZ) near the notch tip. Scanning electron microscopy (SEM) was also used to examine the fracture surfaces at different moisture contents. Bažant's size effect law (SEL) and the modified maximum tangential stress (MMTS) criterion were then used to evaluate the size-dependent apparent Mode I fracture toughness (<em>K</em>_IC) and the size-independent Mode I fracture toughness (<em>K</em>m IC) from the macroscopic response and the local crack-tip stress field, respectively. The results show that the measured <em>K</em>_IC increased with specimen size but decreased with moisture content, whereas the FPZ length increased with both variables, indicating enhanced nonlinear deformation near the notch tip at higher moisture contents. As moisture content increased, <em>K</em>m IC decreased from 111.79 to 42.27 kPa·m^0.5 according to SEL and from 94.61 to 33.92 kPa·m^0.5 according to the MMTS criterion. The fitted SEL and MMTS results reproduced the measured <em>K</em>_IC values with mean relative differences of 1.97% and 1.98%, respectively. The SEL results describe the macroscopic size dependence, whereas the MMTS results relate it to tensile strength and FPZ development. SEM observations showed more evident local openings and separation on the fracture surfaces at higher moisture contents. Comparison with other quasi-brittle materials showed a common increase in normalized apparent fracture toughness with specimen size, although the MMTS-calculated fracture parameters approached their limiting values at different rates. These results indicate that the moisture-related size effect in compacted clay is governed by the combined reduction in tensile resistance and development of the FPZ.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"147 ","pages":"Article 105882"},"PeriodicalIF":6.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148854198","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-parameter inversion from DIC displacement fields using finite-element complex-network graph learning","authors":"Youbin Chen,&nbsp;Hongzhuan Chen,&nbsp;Yingjie Yang,&nbsp;Ruyue Wang","doi":"10.1016/j.tafmec.2026.105906","DOIUrl":"10.1016/j.tafmec.2026.105906","url":null,"abstract":"<div><div>Fracture-parameter identification from digital image correlation (DIC) displacement fields commonly relies on local asymptotic-field fitting near the crack tip and is therefore sensitive to crack-tip localization, fitting-window selection, and measurement noise. Conventional data-driven models use regular pixel representations and cannot explicitly describe the mechanical coupling embedded in the spatial discretization. This study proposes a finite-element complex-network graph-learning (FE-CN) inversion method. Q4 elements serve as the local mechanical front end, and macro-graphs at three scales, 8 × 8, 16 × 16, and 32 × 32, are constructed from fatigue-crack DIC data. The two-channel displacement fields, crack-tip geometry, loading information, and finite-element-derived strain, stress, strain-energy, and internal-force concentration proxies are organized into a stiffness-coupled network for joint identification of the mode-I stress intensity factor <span><math><msub><mi>K</mi><mi>I</mi></msub></math></span> and the non-singular <span><math><mi>T</mi></math></span>-stress. The results show that FE-CN outperforms deep-learning baselines trained under consistent conditions for both parameters. Prediction performance improves and generally stabilizes with graph-scale refinement, with a more pronounced improvement for the <span><math><mi>T</mi></math></span>-stress, and the finite-element nodal mechanical features are the primary source of the accuracy gain. <span><math><msub><mi>K</mi><mi>I</mi></msub></math></span> is more sensitive to missing information at spatially scattered measurement points, whereas <span><math><mi>T</mi></math></span> responds more strongly to missing information in the crack-tip region. Controlled elastoplastic sensitivity analysis and external testing on an independent DIC dataset further delineate the material-response and cross-domain applicability boundaries of the method. This study provides a structured basis for DIC field-of-view integrity inspection, speckle-quality control near the crack tip, and batch identification of fracture parameters.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"147 ","pages":"Article 105906"},"PeriodicalIF":6.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148951302","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":"Fatigue crack morphology reconstruction based on ultrasonic guided waves with a dual-channel adaptive fusion strategy","authors":"Wenyue Zhang,&nbsp;Peng Ni,&nbsp;Xinyu Yang,&nbsp;Wentao He,&nbsp;Junlin Deng","doi":"10.1016/j.tafmec.2026.105900","DOIUrl":"10.1016/j.tafmec.2026.105900","url":null,"abstract":"<div><div>This study proposes an ultrasonic guided wave-based method for fatigue crack detection and morphology reconstruction that integrates multi-sensor data within a dual-channel adaptive probabilistic prediction framework to realize intelligent diagnosis of fatigue damage. A crack length prediction model is established by combining neural networks with uncertainty quantification, while crack depth estimation is realized through a data-driven fatigue crack morphology reconstruction model. Combined with crack growth mechanisms, the depth prediction model is trained on datasets generated from co-simulations of ABAQUS and FRANC3D. Ultrasonic guided wave signals are acquired experimentally and numerically at successive crack growth stages. By integrating CNN with an adaptive attention fusion mechanism, the time–frequency images extracted from dual-channel signals are fed into an uncertainty quantification framework to establish a regression model for crack length prediction. The predicted crack length is used with the morphology reconstruction model to predict the corresponding crack depth, thereby enabling crack morphology inversion. Reconstructed crack profiles are validated against experimental measurements obtained from the beach marking technique. The reconstructed crack-depth evolution shows good agreement with the corresponding reference depth evolution, with a maximum relative depth reconstruction error of 9.8% across the three specimens. The proposed method accurately captures the progressive growth morphology of non-penetrating surface cracks, enables continuous monitoring of crack evolution, and provides reliable predictions of both crack length and depth. These outcomes confirm the robustness and generalization capability of the proposed approach, highlighting its potential for fatigue crack morphology inversion in structural health monitoring applications.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"147 ","pages":"Article 105900"},"PeriodicalIF":6.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148854129","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":"Multiscale fracture mechanism of red sandstone with cross-crack: Insights from theory, experiments and numerical simulations","authors":"Qingqing Shen,&nbsp;Chunhua You,&nbsp;Zelin Liu,&nbsp;Yahan Ouyang","doi":"10.1016/j.tafmec.2026.105893","DOIUrl":"10.1016/j.tafmec.2026.105893","url":null,"abstract":"<div><div>Cross-crack in natural rock masses exert remarkable influences on the stability of tunnel surrounding rock. Investigating the macro-micro fracture mechanisms of rock masses with cross-crack is critical for ensuring the long-term safety of underground engineering structures. This work proposes a novel composite crack-initiation criterion incorporating the <em>T</em>-stress effect for rock with unequal length cross-crack, and reveals its macro-microscopic multi-scale fracture mechanism through theoretical analysis, laboratory tests and phase-field numerical simulations. Firstly, the cross-crack stress intensity factors (SIFs) within a rectangular plate were evaluated by means of the semi-weight function method. Based on the criterion for the maximum tensile-compressive SIF ratio, and with due consideration of the <em>T</em> stress effect, a new composite initiation criterion was formulated, and the initiation parameters for the red sandstone containing cross-crack were estimated. Secondly, digital image correlation (DIC) technology was applied to measure the uniaxial compressive strength of red sandstone with cross-crack, and the fracture tips of the damaged samples were examined via scanning electron microscopy. Then, by introducing polynomial degradation functions and coupling the dissipation factor to characterize the crack propagation behavior under compressive-shear stress conditions, a new composite phase-field model was established. The findings indicate that the polynomial degradation function can better depict the brittle fracture behavior. For unequal length cross-crack under uniaxial compression, the specimen always starts cracking from the initial long crack end first and generates wing cracks, and then the wing cracks gradually expand until failure. The predicted initiation parameters are basically consistent with the experimental parameters, and the fracture trajectories are basically in agreement. This confirms the rationality of the theoretical results; both macro-scale failure patterns and micro-scale morphologies demonstrate tension-dominated fracture features. The findings of this study apply to brittle red sandstone under quasi-static uniaxial compression with specific crack length ratios and intersection angles. The conclusions cannot be directly applied to dynamic loading, confining pressure conditions, or other heterogeneous rock materials without further modification and verification.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"147 ","pages":"Article 105893"},"PeriodicalIF":6.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148854130","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}