Theoretical and Applied Fracture Mechanics最新文献

{"title":"Mesh size identification for cohesive fracture model based on experimentally calibrated FPZ length and FDEM simulation","authors":"Weiqin Wang ,&nbsp;Kekuo Yuan ,&nbsp;Quansheng Liu ,&nbsp;Jianxi Ren ,&nbsp;Ziwei Ding ,&nbsp;Xiaolong Li","doi":"10.1016/j.tafmec.2026.105485","DOIUrl":"10.1016/j.tafmec.2026.105485","url":null,"abstract":"<div><div>Abstract</div><div>Mesh size constitutes a critical parameter governing both computational accuracy and computational efficiency in fracture simulation of rock-like materials employing an advanced hybrid continuum-discrete element method integrated with a cohesive fracture model. However, determining an optimal mesh size remains nontrivial: conventional trial-and-error mesh refinement strategies inherently undermine computational efficiency and lack theoretical grounding. This study presents a systematic approach to mesh size identification via integrated theoretical analysis, experimental validation, and numerical parametric studies within the Cohesive Zone Model (CZM) framework via the combined finite-discrete element method (FDEM), which explicitly captures fracture propagation and fragmentation in simulation. Particular emphasis is placed on identifying a new general approach for optimal mesh size to enhance computational efficiency while preserving solution fidelity, thereby reducing overall computational costs constraints in engineering applications. First, mesh size estimates are derived from extensive fracture mechanics criteria and comprehensive statistical analysis of experimental <em>K</em>_<em>IC</em>–<em>σ</em>_t data across multiple rock types. Second, the Modified Maximum Tangential Stress (MMTS) criterion that incorporates <em>T</em>-stress effects is introduced to correct the fidelity of fracture process zone (FPZ) length (<em>l</em>_<em>FPZ</em>) estimation; predictions derived from the enhanced criterion are validated against independent experimental observations and analytical benchmarks. Third, quantitative evaluation of mesh size effects is conducted through FDEM simulations of uniaxial compressive strength (UCS) and Brazilian Disc (BD) tests. Integration of a meshable <em>l</em>_<em>FPZ</em> from MMTS-based, back-correction inferred from <em>K</em>_<em>IC</em>–<em>σ</em>_t relationships, and FDEM results reveals a robust convergence threshold: computational stability is attained when the FPZ is resolved by approximately 3–4 elements. Finally, heterogeneity effects on mesh size demonstrate that representing grain-scale features with single elements stabilizes rock fracture numerical stability, establishing the mesoscopic grain scale as the lower resolution bound for rock mesh sizing. The methodology and findings hold substantial implications for mesh design in rock fracture simulations and demonstrate the practical feasibility of mesoscale approaches in addressing complex geomechanical simulation challenges through hydro-based techniques.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"143 ","pages":"Article 105485"},"PeriodicalIF":5.6,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189022","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":"Automating the Hartman-Schijve methodology for predicting interlaminar fatigue crack growth in fibre composites","authors":"Ramesh Chandwani ,&nbsp;Chris Timbrell ,&nbsp;B.R.K. Blackman ,&nbsp;Rhys Jones ,&nbsp;Anthony J. Kinloch","doi":"10.1016/j.tafmec.2026.105487","DOIUrl":"10.1016/j.tafmec.2026.105487","url":null,"abstract":"<div><div>The Hartman-Schijve methodology offers a direct route to calculating various fatigue crack growth (FCG) rate curves that are associated with delaminations growing in fibre polymer-matrix composites. However, up to the present, only a ‘manual’ method has been described to deduce the values of the Hartman-Schijve constants that are needed for such calculations. Whilst this manual method may give reasonably acceptable results for calculating the Hartman-Schijve constants, it is a difficult and tedious implementation route. Thus, it may, if the operator is inexperienced, give relatively large errors in the values of the key constants that are needed to calculate the FCG rate curves. Furthermore, for very large data sets there is great difficulty incurred in manipulating such a large amount of data using the ‘manual method’.</div><div>Therefore, the main aim of the present paper has been to introduce a novel computer model and the associated software, ‘Zencrack: Material Curve Fitting Utility’ from Zentech International Limited, UK, to obtain automatically the Hartman-Schijve constants. The aim has been to deduce the ‘worst-case upper-bound’ FCG curve for small, naturally-occurring, delaminations in the composite material, or component. To achieve such an ‘automatic’ method, the current work (a) has taken previously-published algorithms that employ a ‘Total Least Squares’ method for the fitting process of the experimental input data to the Hartman-Schijve equation and (b) has investigated the effect of a normalising scaling factor. It is shown that an automatic calculation that includes all the input data gives the best representation of the Hartman-Schijve constants and is the recommended approach.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"143 ","pages":"Article 105487"},"PeriodicalIF":5.6,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189019","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":"An interaction integral for dynamic crack growth analysis in Mindlin-Reissner plates and shells","authors":"Seyed Hadi Bayat,&nbsp;Mohammad Bagher Nazari,&nbsp;Masoud Mahdizadeh Rokhi","doi":"10.1016/j.tafmec.2026.105458","DOIUrl":"10.1016/j.tafmec.2026.105458","url":null,"abstract":"<div><div>In this paper, numerical tools needed to dynamic crack growth analysis in Mindlin-Reissner plate and shell structures are developed in the eXtended Finite Element Method (XFEM) framework. An interaction integral with proper auxiliary fields is introduced to extract mixed-mode Stress Intensity Factors (SIFs) for in-plane (membrane) and out-of-plane (bending) loadings for a dynamically moving crack. Besides, some relations are derived to relate the interaction integral and dynamic SIFs. These SIFs are employed to predict the crack growth direction using the maximum circumferential tensile stress criterion. An alternative relation for the crack growth speed in plates and shells is presented. Several numerical examples are presented to evaluate the accuracy of the results in modeling both quasi-static and dynamic crack growth in plates and shells, with comparisons made to available analytical and experimental data.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"143 ","pages":"Article 105458"},"PeriodicalIF":5.6,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078168","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":"Mechanical behavior and acoustic emission characteristics of fissured sandstone under low frequency disturbance","authors":"Chengyan Wu ,&nbsp;Dong Wang ,&nbsp;Yujing Jiang ,&nbsp;Yongkui Shi ,&nbsp;Chengyu Miao ,&nbsp;Huichen Xu ,&nbsp;Mengjia Shi","doi":"10.1016/j.tafmec.2026.105486","DOIUrl":"10.1016/j.tafmec.2026.105486","url":null,"abstract":"<div><div>To investigate the mechanical properties and fracture mechanism of single-fissured sandstone under low-frequency disturbance, a creep dynamic disturbance impact loading system was employed to conduct both dynamic and static testing on sandstone samples with single crack, utilizing acoustic emission detection techniques. Simultaneously, the damage process of the sample was deduced by numerical simulation. The results indicate that a smaller crack angle corresponds to reduced compressive strength, elastic modulus, and peak strain when subjected to low-frequency disturbance. As the fracture angle increases, the internal damage evolution of the sample intensifies under low-frequency disturbance, resulting in greater energy accumulation and more significant energy release during instability-induced failure, which is manifested as a higher degree of macro-scale damage. The fracture mode of sandstone samples with pre-existing crack is primarily characterized by tensile-shear compound failure, with the fracture crack exhibiting a distinctive “Y” pattern. The test results hold considerable theoretical significance for understanding the instability mechanisms of fractured surrounding rock, as well as for the prevention and control of dynamic hazards in deep soft rock mines.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"143 ","pages":"Article 105486"},"PeriodicalIF":5.6,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189024","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":"Influence of crack density on energy dissipation and damage evolution in rock–concrete composites under cyclic loading paths","authors":"Jiang Luo,&nbsp;Mingxuan Shen,&nbsp;Bin Du,&nbsp;JieWang,&nbsp;Haiyang Chen","doi":"10.1016/j.tafmec.2026.105474","DOIUrl":"10.1016/j.tafmec.2026.105474","url":null,"abstract":"<div><div>Rock-concrete composite structures are commonly encountered in engineering projects such as tunnels and dams, where pre-existing cracks significantly influence structural stability. Under engineering disturbances, their load-bearing mechanisms become more complex. This study conducted loading-unloading tests via Path I (constant lower limit with stepwise cyclic loading) and Path II (varying upper and lower limits with constant amplitude cycles), combined with acoustic emission monitoring. Based on the division of dissipated energy into damping energy and damage energy, a damage characterization model was established. Results indicate that the number of cracks is the dominant factor affecting macroscopic properties, as it accelerates microcrack coalescence through stress concentration at crack tips, significantly reducing peak strength and stiffness. Path II induced “interface hardening” in single-crack specimens but exacerbated damage in multi-crack specimens due to stress field superposition. The failure mode shifted from tensile failure to tensile-shear composite failure, with Path II being more prone to inducing shear cracks. Acoustic emission results showed a “silent-outburst” pattern in Path I, while damage accumulation was more uniform in Path II. The damage model revealed that when the number of cracks is ≥2, the damage rate under Path II is significantly higher than under Path I, owing to the synergistic effect of variable amplitude loading and stress fields. This study elucidates the coupled damage mechanism of cracks and loading paths, providing a theoretical basis for engineering stability assessment.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"143 ","pages":"Article 105474"},"PeriodicalIF":5.6,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189021","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":"Coupling effects of bedding and rock bridge inclination on the failure behavior of 3D printed layered sandstone specimens","authors":"Xingyu Tao ,&nbsp;Shuyang Yu ,&nbsp;Jun Yu ,&nbsp;Yifei Li ,&nbsp;Shan Zhao ,&nbsp;Jiajie Li","doi":"10.1016/j.tafmec.2026.105482","DOIUrl":"10.1016/j.tafmec.2026.105482","url":null,"abstract":"<div><div>The coupling interaction between bedding and fissures in deep layered rock masses significantly escalates the suddenness and complexity of surrounding rock instability. Consequently, investigating the mechanisms by which weak bedding planes and fissure geometric distributions control rock fracture behavior is of great importance. To address the challenge of experimental discreteness caused by the heterogeneity of natural rocks, additive manufacturing via sand-based 3D printing was employed to produce rock-like samples featuring diverse bedding orientations and double-fissure rock bridge angles. Uniaxial compression tests were conducted, combined with Digital Image Correlation (DIC) and discrete element simulations, to systematically reveal the coupling mechanisms between bedding effects and fissure-induced effects at both macroscopic and mesoscopic scales. The results indicate that: (1) The ultimate fracture manifestations of the samples exhibit significant anisotropy, where the bedding angle and fissure rock bridge inclination jointly determine the load-carrying capacity and overall structural integrity of the rock specimens. (2) Analysis of DIC full-field strain and PFC force chain evolution reveals that low rock bridge inclinations primarily induce stress superposition at crack tips and shear coalescence, manifesting as fissure-dominated failure. Conversely, high rock bridge inclinations trigger a significant stress shielding effect, shifting high-stress zones toward weak bedding planes, which results in splitting along the bedding or mixed-mode failure. (3) Numerical simulations further elucidate the stress propagation laws within the discontinuous medium, confirming the dual role of bedding planes as either stress transmission channels or barrier screens. The results contribute significantly to the theoretical framework of fracture mechanics regarding bedded rock masses containing pre-existing flaws. Furthermore, they offer essential guidance for assessing stability and mitigating geohazards in deep underground projects facing complex geological environments.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"143 ","pages":"Article 105482"},"PeriodicalIF":5.6,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078523","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":"Development of a finite-strain phase-field formulation for thermo-mechanical brittle fracture in Total Lagrangian SPH and its comparative assessment with pseudo-spring model","authors":"Jerome Samuel Stephen ,&nbsp;Md Rushdie Ibne Islam","doi":"10.1016/j.tafmec.2026.105481","DOIUrl":"10.1016/j.tafmec.2026.105481","url":null,"abstract":"<div><div>This work presents the development of a finite-strain phase-field formulation for thermo-mechanical brittle fracture within the Total Lagrangian Smoothed Particle Hydrodynamics (TLSPH) framework and its comparative assessment with the pseudo-spring model. The proposed formulation extends TLSPH to coupled thermo-mechanical conditions through a multiplicative decomposition of the deformation gradient into elastic and thermal components, enabling consistent treatment of large deformations and temperature-dependent stresses. A hyperbolic regularization of the phase-field evolution equation is adopted to enhance stability and alleviate time-step restrictions inherent in parabolic formulations. Four representative problems are investigated: thermal cracking in a double-notched specimen, expansion-induced fracture in a two-layer cylindrical rock, dynamic crack branching in a notched plate under combined loading, and thermal-shock-induced fracture in ceramics. Results are validated against experimental and numerical data, with quantitative comparisons of crack paths, crack-tip velocity, branching angle, and strain–energy dissipation. The phase-field TLSPH formulation accurately captures continuous and parallel crack evolution under severe thermal gradients, whereas the pseudo-spring model efficiently reproduces multiple small radial cracks in heterogeneous media but exhibits spurious local damage under abrupt thermal shocks. The study establishes a robust particle-based framework for thermo-mechanical fracture and clarifies the relative strengths and limitations of continuum and discrete fracture representations within TLSPH.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"143 ","pages":"Article 105481"},"PeriodicalIF":5.6,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078525","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 modified interaction integral approach for XFEM analysis of semipermeable cracks in piezoelectric materials","authors":"Kuldeep Sharma ,&nbsp;Rajalaxmi Rath ,&nbsp;Tinh Quoc Bui","doi":"10.1016/j.tafmec.2026.105477","DOIUrl":"10.1016/j.tafmec.2026.105477","url":null,"abstract":"<div><div>This study introduces a modified interaction integral (MII) approach within the extended finite element method (XFEM) framework to investigate semipermeable cracks in piezoelectric materials. An iterative technique, based on the iterative capacitor analogy (ICA), is developed to compute the semipermeable crack-face electric displacement condition (<span><math><msubsup><mrow><mi>D</mi></mrow><mrow><mi>y</mi></mrow><mrow><mi>c</mi></mrow></msubsup></math></span>). The proposed methodology is validated through three benchmark configurations: center crack, edge crack, and double-edge crack problems. The calculated intensity factors are compared with existing interaction integral methods reported in the literature. For all benchmark cases, the proposed approach demonstrates a notable reduction in percentage error under electro-mechanical loading, especially when the computed <span><math><msubsup><mrow><mi>D</mi></mrow><mrow><mi>y</mi></mrow><mrow><mi>c</mi></mrow></msubsup></math></span> is comparable to the applied electrical loading. In scenarios where <span><math><msubsup><mrow><mi>D</mi></mrow><mrow><mi>y</mi></mrow><mrow><mi>c</mi></mrow></msubsup></math></span> is relatively small (approximately <span><math><msup><mrow><mrow><mo>(</mo><mn>1</mn><mo>/</mo><mn>20</mn><mo>)</mo></mrow></mrow><mrow><mtext>th</mtext></mrow></msup></math></span> or less of the applied electrical loading), the variation in percentage error among the interaction integrals remains within 1%. Thus, in such cases, the standard interaction integral can be confidently employed for fracture mechanics analyses involving semipermeable crack-face conditions. To address inconsistencies in existing solutions for semipermeable edge and double-edge crack problems, new distributed dislocation method (DDM)-based solutions are also developed for comparison with XFEM results. Extensive numerical studies, considering variations in electrical and mechanical loads, polarization angles, and material constants, validate the robustness of the proposed approach in minimizing errors in the evaluation of electric displacement intensity factor (EDIF). Furthermore, the enhanced XFEM framework is employed to analyze macro–micro crack interactions and semipermeable crack-face electric displacement conditions in piezoelectric materials with a single edge-type macro-crack and various configurations of parallel micro-crack arrays.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"143 ","pages":"Article 105477"},"PeriodicalIF":5.6,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146038557","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":"Bearing stability assessment of flawed sandstone considering multi-parameter coupling and analytic hierarchy process: effects of flaw geometric configuration","authors":"Zheng Ma ,&nbsp;Hai Pu ,&nbsp;Kangsheng Xue ,&nbsp;Hao Zhang ,&nbsp;Xiaoyan Liu ,&nbsp;Gaobo Qu ,&nbsp;Dejun Liu ,&nbsp;Qingyu Yi","doi":"10.1016/j.tafmec.2026.105454","DOIUrl":"10.1016/j.tafmec.2026.105454","url":null,"abstract":"<div><div>Ensuring rock mass stability is a fundamental prerequisite for the long-term safety, reliability, and sustainability of underground engineering structures. In this study, sandstone specimens containing parallel pre-existing fractures were selected as research objects. By integrating acoustic emission (AE) and digital image correlation (DIC) techniques, the mechanical response and strain localization evolution of prefabricated sandstone under uniaxial loading were systematically investigated. To quantitatively evaluate the stability characteristics, a comprehensive stability index (SI) was established based on three key parameters: the strength reduction parameter (<em>I</em>_C), brittleness parameter (<em>I</em>_σ), and energy storage parameter (<em>I</em>_U). The Analytic Hierarchy Process (AHP) was applied to determine the relative weights of these parameters, enabling quantitative comparison of sandstone stability under varying fracture geometries. The results demonstrate that the presence of multiple prefabricated fractures markedly degrades the mechanical integrity of sandstone, leading to a reduction in peak strength ranging from approximately 30% to 60%. As the flaw dip angle increases, the peak AE amplitude rises correspondingly, and the failure mode transitions from axial mixed tensile failure to oblique tensile–shear failure. With an increase in the rock bridge angle, AE activity becomes more intense, and the dominant failure mechanism shifts from shear to tensile cracking around the rock bridge zone. Specimens classified within the stable zone generally exhibited larger dip angles (approximately 75°) and rock bridge angles (greater than 90°), whereas those within the hazardous zone were characterized by lower dip angles (approximately 15°) and smaller rock bridge angles (less than or equal to 60°). For specimens with rock bridge angles greater than 90°, approximately 55.6% exhibited pronounced brittle behavior, suggesting a heightened potential for rockburst occurrence.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"143 ","pages":"Article 105454"},"PeriodicalIF":5.6,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189023","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 toughness properties of Q355 steel welded joint considering constraint effects and low-temperature conditions","authors":"Tong Sun ,&nbsp;Yuanqing Wang ,&nbsp;Yongjiu Shi ,&nbsp;Jianlei Zou","doi":"10.1016/j.tafmec.2026.105475","DOIUrl":"10.1016/j.tafmec.2026.105475","url":null,"abstract":"<div><div>This study investigates the low-temperature fracture behavior of Q355 steel welded joints in the base metal (BM), weld metal (WM), and heat-affected zone (HAZ) over a testing temperature range from 23 °C to −100 °C. V-notch Charpy impact tests and Single-Edge Notched Bend (SENB) fracture toughness tests under different constraint conditions were conducted to obtain impact energy (<em>KV</em>2), <em>J</em>-R curves, and characteristic values (<em>J</em>_1C and <em>J</em>_max). The reference temperature <em>T</em>₀ was evaluated using the Master Curve method, and the ductile-to-brittle transition temperature <em>T</em>_t was determined by Boltzmann fitting. The results show that <em>KV</em>2 decreases markedly with decreasing temperature in all regions, indicating a clear ductile-to-brittle transition. The BM exhibits the highest stability of low-temperature toughness, followed by the WM, while the HAZ shows the greatest scatter and the highest sensitivity to temperature reduction. For standard SENB specimens, <em>J</em>-R curves and <em>J</em>_1C values remain nearly constant in the ductile regime, whereas significant differences emerge in the mixed and brittle regimes, with the BM showing the lowest <em>T</em>₀ and the HAZ the highest. For non-standard SENB specimens, reducing crack length and specimen thickness lowers constraint levels and leads to increased fracture toughness and reduced <em>T</em>₀. Transition temperatures <em>T</em>_t obtained from Charpy impact and fracture toughness tests differ significantly, with <em>J</em>_1C providing a conservative assessment and <em>J</em>_max reflecting crack-propagation resistance. Overall, the low-temperature fracture behavior of Q355 steel welded joints is strongly influenced by testing temperature, constraint condition, and material region, with the HAZ remaining the most critical zone for low-temperature fracture resistance.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"143 ","pages":"Article 105475"},"PeriodicalIF":5.6,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189101","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}