Theoretical and Applied Fracture Mechanics最新文献_第10页

Deformation–failure and acoustic emission characteristics of tunnels with fracture zones under loading: Analysis of dip angle effects 荷载作用下裂隙带隧道变形破坏及声发射特征：倾角效应分析

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-03-01 Epub Date: 2025-12-29 DOI: 10.1016/j.tafmec.2025.105428

Kexue Wang , Jun Yang , Yanbo Zhang , Wenhui Bian , Xulong Yao

Fractured zones are common unfavorable geological structures that pose significant risks to tunnel stability. To investigate the deformation and failure mechanisms of tunnels intersecting fractured zones with different inclinations, a series of rock specimens containing fractured zones at dip angles of 30°, 45°, 60°, 75°, and 90° were prepared based on a shallow-buried metro tunnel project. Biaxial compression tests were conducted using acoustic-emission (AE) monitoring and digital image correlation (DIC). The results indicate that the presence of a fractured zone substantially weakens the mechanical properties of the specimens. Relative to the specimens with no fracture zones (NF), the peak strength of the F-30°, F-45°, F-60°, F-75°, and F-90° specimens was reduced by 56.7 %, 45.1 %, 38.1 %, 14.9 %, and 9.8 %, respectively. The evolution of maximum principal strain exhibits pronounced temporal asynchrony and spatial asymmetry, while tensile cracking dominates the failure behavior, accounting for more than 80 % of all cracks. Prior to peak strength, the AF parameter drops sharply, and the proportion of shear cracking reaches its maximum. Analysis of the AE peak-frequency distributions reveals two distinct failure types. Type-I specimens (F-30° and F-45°), dominated by low-frequency events (>95 %), fail primarily through slow, large-scale slip along the fractured-zone interface. Type-II specimens (F-60°, F-75°, F-90°) exhibit high-frequency AE events that are 2–5 times more abundant than in type-I specimens, reflecting intense microcrack initiation, propagation, and coalescence driven by stress concentration at the fractured-zone tips and the tunnel boundary. Two characteristic failure sequences were identified: F–T, in which deformation and failure initiate in the fractured zone prior to the tunnel, and T–F, in which tunnel deformation and failure develop earlier than those in the fractured zone. The results indicate that the inclination of the fractured zone governs the tunnel failure mode and alters the sequence of damage evolution. The F-30°, F-45°, and F-60° specimens follow the F–T sequence, whereas the F-75° and F-90° specimens follow the T–F sequence. These findings provide theoretical insights and practical guidance for instability assessment and support design in tunnels crossing fractured zones

裂缝带是常见的不利地质构造，对隧道的稳定性构成重大威胁。为研究不同倾角下隧道贯通裂隙带的变形破坏机理，以某浅埋地铁隧道为例，在30°、45°、60°、75°和90°倾角下制备了一系列裂隙带岩样。采用声发射（AE）监测和数字图像相关（DIC）进行双轴压缩试验。结果表明，断裂带的存在大大削弱了试样的力学性能。F-30°、F-45°、F-60°、F-75°和F-90°试件的峰值强度分别比无断裂带试件降低56.7%、45.1%、38.1%、14.9%和9.8%。最大主应变演化表现出明显的时间非同时性和空间非对称性，而拉伸裂纹主导破坏行为，占所有裂纹的80%以上。峰值强度之前，AF参数急剧下降，剪切开裂比例达到最大值。对声发射峰频分布的分析揭示了两种不同的破坏类型。i型试件（F-30°和F-45°）主要由低频事件（> 95%）主导，主要通过沿断裂带界面缓慢的大规模滑动破坏。ii型试样（F-60°，F-75°，F-90°）的高频声发射事件比i型试样多2-5倍，反映了在断裂带尖端和隧道边界应力集中驱动下的强烈微裂纹萌生、扩展和合并。确定了两种典型的破坏序列：F-T阶段，裂隙区变形破坏先于巷道发生；T-F阶段，巷道变形破坏先于裂隙区发生。结果表明，裂隙区的倾角决定着隧道的破坏模式，并改变着损伤演化的顺序。F-30°、F-45°和F-60°试样遵循F-T序列，而F-75°和F-90°试样遵循T-F序列。这些研究结果为穿越裂隙带的隧道失稳评估和支护设计提供了理论见解和实践指导

{"title":"Deformation–failure and acoustic emission characteristics of tunnels with fracture zones under loading: Analysis of dip angle effects","authors":"Kexue Wang , Jun Yang , Yanbo Zhang , Wenhui Bian , Xulong Yao","doi":"10.1016/j.tafmec.2025.105428","DOIUrl":"10.1016/j.tafmec.2025.105428","url":null,"abstract":"<div><div>Fractured zones are common unfavorable geological structures that pose significant risks to tunnel stability. To investigate the deformation and failure mechanisms of tunnels intersecting fractured zones with different inclinations, a series of rock specimens containing fractured zones at dip angles of 30°, 45°, 60°, 75°, and 90° were prepared based on a shallow-buried metro tunnel project. Biaxial compression tests were conducted using acoustic-emission (AE) monitoring and digital image correlation (DIC). The results indicate that the presence of a fractured zone substantially weakens the mechanical properties of the specimens. Relative to the specimens with no fracture zones (NF), the peak strength of the F-30°, F-45°, F-60°, F-75°, and F-90° specimens was reduced by 56.7 %, 45.1 %, 38.1 %, 14.9 %, and 9.8 %, respectively. The evolution of maximum principal strain exhibits pronounced temporal asynchrony and spatial asymmetry, while tensile cracking dominates the failure behavior, accounting for more than 80 % of all cracks. Prior to peak strength, the AF parameter drops sharply, and the proportion of shear cracking reaches its maximum. Analysis of the AE peak-frequency distributions reveals two distinct failure types. Type-I specimens (F-30° and F-45°), dominated by low-frequency events (>95 %), fail primarily through slow, large-scale slip along the fractured-zone interface. Type-II specimens (F-60°, F-75°, F-90°) exhibit high-frequency AE events that are 2–5 times more abundant than in type-I specimens, reflecting intense microcrack initiation, propagation, and coalescence driven by stress concentration at the fractured-zone tips and the tunnel boundary. Two characteristic failure sequences were identified: F–T, in which deformation and failure initiate in the fractured zone prior to the tunnel, and T–F, in which tunnel deformation and failure develop earlier than those in the fractured zone. The results indicate that the inclination of the fractured zone governs the tunnel failure mode and alters the sequence of damage evolution. The F-30°, F-45°, and F-60° specimens follow the F–T sequence, whereas the F-75° and F-90° specimens follow the T–F sequence. These findings provide theoretical insights and practical guidance for instability assessment and support design in tunnels crossing fractured zones</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"142 ","pages":"Article 105428"},"PeriodicalIF":5.6,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884071","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}

引用次数: 0

Biaxial compression fracture of granite with coupled flaws: mechanisms of synergistic weakening and the critical role of confinement 带耦合缺陷的花岗岩双轴压缩断裂：协同弱化机制及约束的关键作用

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-03-01 Epub Date: 2025-12-28 DOI: 10.1016/j.tafmec.2025.105425

Liming Tang , Zongyu Ma , Chun'an Tang , Wenshuo Duan , Xin Liang , Xu Chen

The stability of surrounding rock in deep engineering is controlled by the mechanical behavior of defects such as holes and cracks present in hard rocks under multi-axial stress conditions. To elucidate the fracture mechanism of typical hard rock (granite), this study combines biaxial compression physical experiments (incorporating Digital Image Correlation (DIC) technology) with three-dimensional numerical simulations to capture the fracturing process. A comparative analysis was performed on the macroscopic and mesoscopic failure processes of four sample types: hole-crack composite defects, single holes, double cracks, and intact samples. This study found that the peak strength and elastic modulus of the specimens show a decreasing trend with the increase of the proportion of defect volume, with samples exhibiting hole-crack composite defects demonstrating the most significant synergistic deterioration effect. The failure mechanism shifts from shear-slip along closed prefabricated cracks under low confinement (0, 5 MPa) to tensile-initiated opening at high confinement (10, 15 MPa), fundamentally altering the fracture pattern. Full-field strain analysis using DIC indicates that the failure of hole-crack composite defects is dominated by wing cracks originating from the tips of cracks and extending toward the hole walls, whereas the failure of single hole samples is controlled by shear cracks along the hole walls. Numerical simulations at the meso-scale clarify that the interaction between stress concentration at the holes and the brittle propagation path provided by the cracks is the intrinsic mechanism behind the synergistic deterioration phenomenon. Intense shear strain concentration at the hole-crack interface ultimately leads to hole fracture, spalling, and block detachment. The fracturing mechanism of hard rocks with composite defects under high confining pressure revealed in this study provides an important theoretical basis for the assessment and control of stability in surrounding rock for deep engineering projects.

在多轴应力条件下，深部工程围岩的稳定性是由坚硬岩石中存在的孔洞、裂纹等缺陷的力学行为控制的。为了阐明典型硬岩（花岗岩）的断裂机理，本研究将双轴压缩物理实验（结合数字图像相关（DIC）技术）与三维数值模拟相结合，捕捉断裂过程。对比分析了孔-裂纹复合缺陷、单孔、双裂纹和完整试样的宏观和细观破坏过程。研究发现，随着缺陷体积比例的增加，试件的峰值强度和弹性模量呈下降趋势，其中孔-裂纹复合缺陷试件的协同变质效应最为显著。破坏机制从低约束（0.5 MPa）下沿闭合预制裂缝的剪切滑移转变为高约束（10、15 MPa）下的拉伸开启，从根本上改变了断裂模式。基于DIC的现场应变分析表明，孔-裂纹复合缺陷的破坏主要由起源于裂纹尖端并向孔壁扩展的翼状裂纹主导，而单孔试样的破坏则受沿孔壁方向的剪切裂纹控制。细观数值模拟表明，孔洞处应力集中与裂纹提供的脆性扩展路径之间的相互作用是协同劣化现象背后的内在机制。孔-裂纹界面处强烈的剪切应变集中最终导致孔破裂、剥落和块体脱落。研究揭示了高围压下含复合缺陷的硬岩破裂机理，为深部工程项目围岩稳定性评价与控制提供了重要的理论依据。

{"title":"Biaxial compression fracture of granite with coupled flaws: mechanisms of synergistic weakening and the critical role of confinement","authors":"Liming Tang , Zongyu Ma , Chun'an Tang , Wenshuo Duan , Xin Liang , Xu Chen","doi":"10.1016/j.tafmec.2025.105425","DOIUrl":"10.1016/j.tafmec.2025.105425","url":null,"abstract":"<div><div>The stability of surrounding rock in deep engineering is controlled by the mechanical behavior of defects such as holes and cracks present in hard rocks under multi-axial stress conditions. To elucidate the fracture mechanism of typical hard rock (granite), this study combines biaxial compression physical experiments (incorporating Digital Image Correlation (DIC) technology) with three-dimensional numerical simulations to capture the fracturing process. A comparative analysis was performed on the macroscopic and mesoscopic failure processes of four sample types: hole-crack composite defects, single holes, double cracks, and intact samples. This study found that the peak strength and elastic modulus of the specimens show a decreasing trend with the increase of the proportion of defect volume, with samples exhibiting hole-crack composite defects demonstrating the most significant synergistic deterioration effect. The failure mechanism shifts from shear-slip along closed prefabricated cracks under low confinement (0, 5 MPa) to tensile-initiated opening at high confinement (10, 15 MPa), fundamentally altering the fracture pattern. Full-field strain analysis using DIC indicates that the failure of hole-crack composite defects is dominated by wing cracks originating from the tips of cracks and extending toward the hole walls, whereas the failure of single hole samples is controlled by shear cracks along the hole walls. Numerical simulations at the meso-scale clarify that the interaction between stress concentration at the holes and the brittle propagation path provided by the cracks is the intrinsic mechanism behind the synergistic deterioration phenomenon. Intense shear strain concentration at the hole-crack interface ultimately leads to hole fracture, spalling, and block detachment. The fracturing mechanism of hard rocks with composite defects under high confining pressure revealed in this study provides an important theoretical basis for the assessment and control of stability in surrounding rock for deep engineering projects.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"142 ","pages":"Article 105425"},"PeriodicalIF":5.6,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884136","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}

引用次数: 0

Fracture behavior of thermally-damaged granite containing pre-existing central hole and cross-flaws under uniaxial loading: Experiments and finite difference modeling 含预先存在的中心孔和交叉缺陷的热损伤花岗岩在单轴载荷下的断裂行为：实验和有限差分模型

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-03-01 Epub Date: 2025-12-19 DOI: 10.1016/j.tafmec.2025.105417

Lan Zeng , Xuqi Liang , Shi Liu

The interaction of thermal damage and rock pre-existing flaws in deep underground environments is crucial for understanding deep rock engineering design. Uniaxial load experiments and simulations were performed on granite that had pre-existing central hole and cross-flaws exposed to varying temperatures. Five heterogeneity models of rock masses with different dip angles were established, considering random mineral composition. The thermal damage state of granite subjected to laboratory heat treatments was assessed. The macroscopic crack, represented by softened plastic strain, and the evolution of the displacement field were investigated. The following results were obtained. During the simulated heating at 10 °C/min, thermally induced microcracks occurred due to an increase in plastic tensile strain, while the plastic shear strain was still small until 750 °C. At the same temperature, the relationship between the peak stress and the dip angle was inverted V-shaped. The peak stress increased and decreased with the crack dip angle and reached the maximum at a dip angle of 45°. The stress-strain curves from the experiment and simulation showed similar trends. The failure types consisted of initial shear or tensile failure, followed by tensile-shear failure in the yield softening stage. The evolution of failure modes in heat-treated models is driven by the thermal degradation of key mechanical parameters, including cohesion and tensile strength. Except for the 45° samples, which showed major cracks along the tips of a pre-existing flaws pair in a straight line, all other samples developed cracks at the ends of the pair, near the horizontal direction. The evolution of the Z-direction displacement field and velocity vector showed that the specimen's ultimate failure was caused by crack initiation and propagation along the pre-existing crack tip, followed by sliding. This study provides insights for the stability assessment of deep underground engineering structures affected by high temperature geothermal.

在深部地下环境中，热损伤与岩石预先存在缺陷的相互作用是理解深部岩石工程设计的关键。在不同温度条件下，对具有中心孔和交叉缺陷的花岗岩进行了单轴载荷实验和模拟。考虑随机矿物组成，建立了5种不同倾角岩体的非均质性模型。对实验室热处理后花岗岩的热损伤状态进行了评价。研究了以软化塑性应变为代表的宏观裂纹和位移场的演化规律。得到了以下结果：在10°C/min的模拟加热过程中，由于塑性拉伸应变的增加而产生热致微裂纹，而塑性剪切应变在750°C之前仍然很小。在相同温度下，峰值应力与倾角呈倒v型关系。峰值应力随裂纹倾角的增大而减小，在倾角为45°时达到最大值。实验和模拟得到的应力-应变曲线呈现出相似的趋势。破坏类型主要为初始剪切破坏或拉伸破坏，其次是屈服软化阶段的拉剪破坏。热处理模型的破坏模式演变是由关键力学参数（包括内聚力和抗拉强度）的热退化驱动的。除了45°试样沿已存在的缺陷对的尖端呈直线状出现主要裂纹外，所有其它试样都在靠近水平方向的缺陷对的末端出现裂纹。z向位移场和速度矢量的演化表明，试样的最终破坏是由裂纹萌生和沿裂纹尖端扩展引起的，然后是滑动。该研究为高温地热作用下深部地下工程结构的稳定性评价提供了参考。

{"title":"Fracture behavior of thermally-damaged granite containing pre-existing central hole and cross-flaws under uniaxial loading: Experiments and finite difference modeling","authors":"Lan Zeng , Xuqi Liang , Shi Liu","doi":"10.1016/j.tafmec.2025.105417","DOIUrl":"10.1016/j.tafmec.2025.105417","url":null,"abstract":"<div><div>The interaction of thermal damage and rock pre-existing flaws in deep underground environments is crucial for understanding deep rock engineering design. Uniaxial load experiments and simulations were performed on granite that had pre-existing central hole and cross-flaws exposed to varying temperatures. Five heterogeneity models of rock masses with different dip angles were established, considering random mineral composition. The thermal damage state of granite subjected to laboratory heat treatments was assessed. The macroscopic crack, represented by softened plastic strain, and the evolution of the displacement field were investigated. The following results were obtained. During the simulated heating at 10 °C/min, thermally induced microcracks occurred due to an increase in plastic tensile strain, while the plastic shear strain was still small until 750 °C. At the same temperature, the relationship between the peak stress and the dip angle was inverted V-shaped. The peak stress increased and decreased with the crack dip angle and reached the maximum at a dip angle of 45°. The stress-strain curves from the experiment and simulation showed similar trends. The failure types consisted of initial shear or tensile failure, followed by tensile-shear failure in the yield softening stage. The evolution of failure modes in heat-treated models is driven by the thermal degradation of key mechanical parameters, including cohesion and tensile strength. Except for the 45° samples, which showed major cracks along the tips of a pre-existing flaws pair in a straight line, all other samples developed cracks at the ends of the pair, near the horizontal direction. The evolution of the <em>Z</em>-direction displacement field and velocity vector showed that the specimen's ultimate failure was caused by crack initiation and propagation along the pre-existing crack tip, followed by sliding. This study provides insights for the stability assessment of deep underground engineering structures affected by high temperature geothermal.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"142 ","pages":"Article 105417"},"PeriodicalIF":5.6,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840457","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}

引用次数: 0

Experimental study on the crack propagation characteristic of coal specimens with offset cracks and the I-II mixed SIF variation by using ultrafast time-resolution method 基于超快时间分辨方法的煤样偏置裂纹扩展特性及I-II混合SIF变化试验研究

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-03-01 Epub Date: 2025-12-14 DOI: 10.1016/j.tafmec.2025.105398

Mingyuan Zhang , Muao Shen , Shankun Zhao , Dejian Li , Yingjun Li

In coal mining, mixed-mode I-II fractures caused by offset cracks are commonly observed. While previous research has primarily focused on stress intensity factors (SIFs) at the crack tip during fracture initiation, the variation of SIFs during crack propagation has received limited attention. As the SIF is a singular parameter, the precise localization of the crack tip is critical for its determination. However, traditional high-speed photography and visual localization methods often introduce systematic errors in experimental measurements. Therefore, this study employs an ultrafast time-resolution method (15 ps) based on pulsed laser technology combined with an immune algorithm to eliminate such errors and calculate I-II mixed-mode SIFs. Semi-circular bend (SCB) experiments were conducted on coal specimens with offset fractures positioned at 5 mm, 10 mm, and 15 mm from the center. Experimental results demonstrate that both Mode I and Mode II SIFs at crack initiation increase with greater offset distances. Notably, a significant decrease in SIFs is observed after the onset of crack propagation. Additionally, the energy release rates at initiation were measured as 140.77 J/m², 328.45 J/m², and 2063.61 J/m², showing a clear upward trend with increasing offset distance. This paper presents a novel experimental approach for characterizing the coal fracture process and SIF evolution, providing valuable insights for laboratory testing in rock mechanics.

在煤矿开采中，常观察到由偏置裂缝引起的I-II型混合模式裂缝。以往的研究主要集中在裂纹尖端的应力强度因子（SIFs）上，而对裂纹扩展过程中SIFs的变化关注较少。由于SIF是一个奇异参数，裂纹尖端的精确定位是确定SIF的关键。然而，传统的高速摄影和视觉定位方法往往会在实验测量中引入系统误差。因此，本研究采用基于脉冲激光技术的超快时间分辨率方法（15ps）结合免疫算法消除此类误差，计算I-II混合模SIFs。在离中心5 mm、10 mm和15 mm的偏置裂缝处对煤样进行了半圆弯曲试验。实验结果表明，裂纹起裂时的I型和II型SIFs均随偏移距离增大而增大。值得注意的是，在裂纹扩展开始后，观察到SIFs显著降低。初始能量释放速率分别为140.77 J/m2、328.45 J/m2和2063.61 J/m2，随着偏移距离的增加，能量释放速率呈明显上升趋势。本文提出了一种新的实验方法来表征煤的破裂过程和SIF演化，为岩石力学的实验室测试提供了有价值的见解。

{"title":"Experimental study on the crack propagation characteristic of coal specimens with offset cracks and the I-II mixed SIF variation by using ultrafast time-resolution method","authors":"Mingyuan Zhang , Muao Shen , Shankun Zhao , Dejian Li , Yingjun Li","doi":"10.1016/j.tafmec.2025.105398","DOIUrl":"10.1016/j.tafmec.2025.105398","url":null,"abstract":"<div><div>In coal mining, mixed-mode I-II fractures caused by offset cracks are commonly observed. While previous research has primarily focused on stress intensity factors (SIFs) at the crack tip during fracture initiation, the variation of SIFs during crack propagation has received limited attention. As the SIF is a singular parameter, the precise localization of the crack tip is critical for its determination. However, traditional high-speed photography and visual localization methods often introduce systematic errors in experimental measurements. Therefore, this study employs an ultrafast time-resolution method (15 ps) based on pulsed laser technology combined with an immune algorithm to eliminate such errors and calculate I-II mixed-mode SIFs. Semi-circular bend (SCB) experiments were conducted on coal specimens with offset fractures positioned at 5 mm, 10 mm, and 15 mm from the center. Experimental results demonstrate that both Mode I and Mode II SIFs at crack initiation increase with greater offset distances. Notably, a significant decrease in SIFs is observed after the onset of crack propagation. Additionally, the energy release rates at initiation were measured as 140.77 J/m<sup>2</sup>, 328.45 J/m<sup>2</sup>, and 2063.61 J/m<sup>2</sup>, showing a clear upward trend with increasing offset distance. This paper presents a novel experimental approach for characterizing the coal fracture process and SIF evolution, providing valuable insights for laboratory testing in rock mechanics.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"142 ","pages":"Article 105398"},"PeriodicalIF":5.6,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840451","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}

引用次数: 0

A study on the fracture mechanical properties and propagation mechanism of coarse aggregate-engineered cementitious composites under preloading 预压条件下粗集料工程胶凝复合材料断裂力学性能及扩展机理研究

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-03-01 Epub Date: 2025-12-03 DOI: 10.1016/j.tafmec.2025.105362

Zetian Zhang , Lei Xie , Xinjian Sun , Zhenpeng Yu , Ligang Jing , Xiaoli Xu , Yifan Shui

Although Engineered Cementitious Composite (ECC) materials exhibit high ductility, their engineering application is restricted by high shrinkage rates and costs; moreover, under the action of historical loads (e.g., initial static loads), ECC may experience damage before reaching their ultimate bearing capacities. To improve the safety and economic performance of ECC, Coarse Aggregate-ECC (CA-ECC) specimens with 4 different CA contents were prepared in this study, and the effects of 4 different preloading ratios were investigated in order to evaluate the fracture properties of CA-ECC under preloading and to clarify the underlying mechanism from both macro- and micro-perspectives. The results showed that ECC containing CA maintained excellent mechanical properties and deformability, and appropriate preloading can effectively mitigate the negative effects caused by CA. When the CA content was 30 % and the preloading ratio was 60 %, the Crack Mouth Opening Displacement (CMOD) of the specimen retained approximately 35.5 % of that of the original ECC specimen, which was about 30 times that of ordinary concrete. Then, combined with Digital Image Correlation (DIC) and microscopic testing methods, the interface layer between each phase medium and the matrix of CA-ECC was analyzed, and the crack initiation and propagation trends were revealed. Further, by comparing macroscopic properties and microstructural characteristics, the unique “fiber-wrapping-CA” effect in CA-ECC and the influence of preloading on the action mechanism of this effect were clarified. Overall, the findings provide theoretical support for the design and engineering application of ECC materials.

尽管工程胶凝复合材料（ECC）具有高延展性，但其工程应用受到高收缩率和高成本的限制；此外，在历史荷载（如初始静荷载）的作用下，ECC可能在达到极限承载能力之前发生破坏。为了提高ECC的安全性和经济性，本研究制备了4种不同CA含量的粗骨料-ECC （CA-ECC）试件，并研究了4种不同预压比例对CA-ECC的影响，从宏观和微观两个角度评价了CA-ECC在预压下的断裂性能，并阐明了其潜在的机制。结果表明：含CA的ECC保持了优异的力学性能和变形能力，适当的预压可以有效缓解CA的负面影响。当CA含量为30%，预压比为60%时，试件的裂缝张开位移（CMOD）保持在原始ECC试件的35.5%左右，是普通混凝土的30倍左右。然后，结合数字图像相关（DIC）和显微测试方法，分析了CA-ECC基体与各相介质之间的界面层，揭示了裂纹的起裂和扩展趋势。进一步，通过对比CA-ECC的宏观性能和微观结构特征，阐明了CA-ECC中独特的“纤维缠绕- ca”效应以及预压对该效应作用机理的影响。研究结果为ECC材料的设计和工程应用提供了理论支持。

{"title":"A study on the fracture mechanical properties and propagation mechanism of coarse aggregate-engineered cementitious composites under preloading","authors":"Zetian Zhang , Lei Xie , Xinjian Sun , Zhenpeng Yu , Ligang Jing , Xiaoli Xu , Yifan Shui","doi":"10.1016/j.tafmec.2025.105362","DOIUrl":"10.1016/j.tafmec.2025.105362","url":null,"abstract":"<div><div>Although Engineered Cementitious Composite (ECC) materials exhibit high ductility, their engineering application is restricted by high shrinkage rates and costs; moreover, under the action of historical loads (e.g., initial static loads), ECC may experience damage before reaching their ultimate bearing capacities. To improve the safety and economic performance of ECC, Coarse Aggregate-ECC (CA-ECC) specimens with 4 different CA contents were prepared in this study, and the effects of 4 different preloading ratios were investigated in order to evaluate the fracture properties of CA-ECC under preloading and to clarify the underlying mechanism from both macro- and micro-perspectives. The results showed that ECC containing CA maintained excellent mechanical properties and deformability, and appropriate preloading can effectively mitigate the negative effects caused by CA. When the CA content was 30 % and the preloading ratio was 60 %, the Crack Mouth Opening Displacement (CMOD) of the specimen retained approximately 35.5 % of that of the original ECC specimen, which was about 30 times that of ordinary concrete. Then, combined with Digital Image Correlation (DIC) and microscopic testing methods, the interface layer between each phase medium and the matrix of CA-ECC was analyzed, and the crack initiation and propagation trends were revealed. Further, by comparing macroscopic properties and microstructural characteristics, the unique “fiber-wrapping-CA” effect in CA-ECC and the influence of preloading on the action mechanism of this effect were clarified. Overall, the findings provide theoretical support for the design and engineering application of ECC materials.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"142 ","pages":"Article 105362"},"PeriodicalIF":5.6,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145738588","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}

引用次数: 0

Dynamic fracture behavior of 3D-printed composites reinforced with continuous fibers 连续纤维增强3d打印复合材料的动态断裂行为

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-03-01 Epub Date: 2025-12-15 DOI: 10.1016/j.tafmec.2025.105405

Mohammad Reza Khosravani , Sankalp Patil , Payam Soltani , Georg Ganzenmüller , Stefan Hiermaier , Tamara Reinicke

This study aims to analyze the influence of continuous fiber reinforcement on the dynamic behavior of 3D-printed composites. To this end, semicircular bending (SCB) test coupons were designed and printed using the fused filament fabrication (FFF) technique. Particularly, nylon material was used as a matrix in all specimens, while fiberglass was utilized as the reinforced material. Since printing orientation has a significant influence on the mechanical behavior of 3D-printed components, the samples were printed in different directions. In a series of tests, the SCB specimens were impacted using a split Hopkinson pressure bar (SHPB) with a strain rate of 100 s⁻¹. In this research, a high-speed photograph system was used with a focus on the SCB specimens to capture their deformation behaviors. The results of dynamic three-point bending tests indicate that the maximum force increased by 190.2% and 238.1% in the specimens printed in ZY and YZ orientations, respectively, as a result of fiber reinforcing. The documented outcomes can be used for the design and production of 3D-printed composites with enhanced structural performance and customized mechanical strength.

本研究旨在分析连续纤维增强对3d打印复合材料动态性能的影响。为此，采用熔丝制造（FFF）技术设计并打印了半圆弯曲（SCB）测试片。其中，所有试件均采用尼龙材料作为基体，玻璃纤维作为增强材料。由于打印方向对3d打印部件的力学行为有显著影响，因此将样品沿不同方向打印。在一系列试验中，采用应变速率为100 s−1的分离式霍普金森压杆（SHPB）对SCB试样进行冲击。在本研究中，采用高速摄影系统，聚焦于SCB试样，捕捉其变形行为。动态三点弯曲试验结果表明，在ZY方向和YZ方向上进行纤维增强后，试样的最大受力分别提高了190.2%和238.1%。记录的结果可用于设计和生产具有增强结构性能和定制机械强度的3d打印复合材料。

{"title":"Dynamic fracture behavior of 3D-printed composites reinforced with continuous fibers","authors":"Mohammad Reza Khosravani , Sankalp Patil , Payam Soltani , Georg Ganzenmüller , Stefan Hiermaier , Tamara Reinicke","doi":"10.1016/j.tafmec.2025.105405","DOIUrl":"10.1016/j.tafmec.2025.105405","url":null,"abstract":"<div><div>This study aims to analyze the influence of continuous fiber reinforcement on the dynamic behavior of 3D-printed composites. To this end, semicircular bending (SCB) test coupons were designed and printed using the fused filament fabrication (FFF) technique. Particularly, nylon material was used as a matrix in all specimens, while fiberglass was utilized as the reinforced material. Since printing orientation has a significant influence on the mechanical behavior of 3D-printed components, the samples were printed in different directions. In a series of tests, the SCB specimens were impacted using a split Hopkinson pressure bar (SHPB) with a strain rate of 100 s<sup>−1</sup>. In this research, a high-speed photograph system was used with a focus on the SCB specimens to capture their deformation behaviors. The results of dynamic three-point bending tests indicate that the maximum force increased by 190.2% and 238.1% in the specimens printed in ZY and YZ orientations, respectively, as a result of fiber reinforcing. The documented outcomes can be used for the design and production of 3D-printed composites with enhanced structural performance and customized mechanical strength.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"142 ","pages":"Article 105405"},"PeriodicalIF":5.6,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790870","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}

引用次数: 0

Synergistic toughening effect of coarse aggregate and hybrid steel fibres on the evolution of fracture process zone in UHPC under Mode I crack tip deformation 粗骨料和混杂钢纤维对ⅰ型裂纹尖端变形下UHPC断裂过程区的协同增韧作用

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-03-01 Epub Date: 2025-12-04 DOI: 10.1016/j.tafmec.2025.105355

Kashif Naukhez, R. Vidya Sagar, J.M. Chandra Kishen

This article investigates the synergistic toughening effect of coarse aggregate (CA) and steel fibres on fracture process zone (FPZ) development in ultra high performance concrete (UHPC). Two specimens, UHPC without fibres, UHPC(NF), and UHPC with hybrid fibres, UHPC(HB), were tested under Mode I crack tip deformation. Digital image correlation (DIC) and acoustic emission (AE) testing were employed to provide insights into the evolution of FPZ. FPZ length (

l_{FPZ}

) was evaluated using the horizontal displacement gap method, while FPZ and fracture core zone (FCZ) widths were determined from AE event density distributions. In addition, micro-CT analysis was conducted to examine porosity and pore size distribution, as well as their influence on FPZ behaviour. It was observed that the positive synergistic interaction between hybrid fibres and CA governed the FPZ evolution and resulted in a substantially superior work of fracture that exceeded the arithmetic sum of reference mixes. This synergy was likely associated with reduced porosity and ultimately a denser microstructure, leading to a stable post-peak phase and a gradual reduction in

l_{F P Z}

in UHPC(HB) after its full development, in contrast to the rapid decrease in UHPC(NF). This confirmed that the positive synergy is crucial for sustaining residual toughness and stability, thereby encouraging the use of hybrid fibres in UHPC incorporating CA for applications demanding high structural ductility.

研究了粗骨料和钢纤维对超高性能混凝土断裂过程区发育的协同增韧作用。对无纤维UHPC（NF）和混杂纤维UHPC（HB）两种试样进行I型裂纹尖端变形试验。采用数字图像相关（DIC）和声发射（AE）测试来深入了解FPZ的演变。利用水平位移间隙法评估FPZ长度（lFPZ），利用声发射事件密度分布确定FPZ和裂缝核心区宽度（FCZ）。此外，还进行了微ct分析，以检查孔隙率和孔径分布，以及它们对FPZ行为的影响。研究发现，混合纤维和CA之间的正协同作用控制了FPZ的演化，并导致了比参考混合材料的算术总和更大的裂缝功。这种协同作用可能与孔隙度降低和最终致密的微观结构有关，导致峰值后阶段稳定，UHPC（HB）中lFPZ在完全发育后逐渐减少，而UHPC（NF）中的lFPZ则迅速减少。这证实了积极的协同作用对于维持残余韧性和稳定性至关重要，因此鼓励在含有CA的UHPC中使用混合纤维，以满足要求高结构延展性的应用。

{"title":"Synergistic toughening effect of coarse aggregate and hybrid steel fibres on the evolution of fracture process zone in UHPC under Mode I crack tip deformation","authors":"Kashif Naukhez, R. Vidya Sagar, J.M. Chandra Kishen","doi":"10.1016/j.tafmec.2025.105355","DOIUrl":"10.1016/j.tafmec.2025.105355","url":null,"abstract":"<div><div>This article investigates the synergistic toughening effect of coarse aggregate (CA) and steel fibres on fracture process zone (FPZ) development in ultra high performance concrete (UHPC). Two specimens, UHPC without fibres, UHPC(NF), and UHPC with hybrid fibres, UHPC(HB), were tested under Mode I crack tip deformation. Digital image correlation (DIC) and acoustic emission (AE) testing were employed to provide insights into the evolution of FPZ. FPZ length (<span><math><msub><mrow><mi>l</mi></mrow><mrow><mtext>FPZ</mtext></mrow></msub></math></span>) was evaluated using the horizontal displacement gap method, while FPZ and fracture core zone (FCZ) widths were determined from AE event density distributions. In addition, micro-CT analysis was conducted to examine porosity and pore size distribution, as well as their influence on FPZ behaviour. It was observed that the positive synergistic interaction between hybrid fibres and CA governed the FPZ evolution and resulted in a substantially superior work of fracture that exceeded the arithmetic sum of reference mixes. This synergy was likely associated with reduced porosity and ultimately a denser microstructure, leading to a stable post-peak phase and a gradual reduction in <span><math><msub><mrow><mi>l</mi></mrow><mrow><mi>F</mi><mi>P</mi><mi>Z</mi></mrow></msub></math></span> in UHPC(HB) after its full development, in contrast to the rapid decrease in UHPC(NF). This confirmed that the positive synergy is crucial for sustaining residual toughness and stability, thereby encouraging the use of hybrid fibres in UHPC incorporating CA for applications demanding high structural ductility.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"142 ","pages":"Article 105355"},"PeriodicalIF":5.6,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145738645","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}

引用次数: 0

Fracture behavior of randomly oriented chopped/short fiber-reinforced composite materials: A combined experimental, numerical, and machine learning approach 随机取向短切/短纤维增强复合材料的断裂行为：实验、数值和机器学习相结合的方法

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-03-01 Epub Date: 2025-12-06 DOI: 10.1016/j.tafmec.2025.105381

Sayed Mohammad Hossein Izadi

This study investigates the fracture behavior of randomly oriented chopped/short fiber-reinforced composite materials as a function of fiber volume fraction. Composite specimens with fiber contents of 0 %, 20 %, 30 %, 40 %, 50 %, and 60 % were fabricated using 4 mm chopped glass fibers and tested under Mode I loading using three-point bending experiments and validated finite element models. The effects of fiber volume fraction on key fracture parameters, including fracture toughness, break force, maximum tolerated load, and mid-span deflection at maximum load, were systematically examined. Additionally, the strain energy absorbed during crack initiation (pre-peak) and propagation (post-peak) was calculated to analyze toughening mechanisms such as fracture process zone development, fiber distribution, and fiber bridging. Results revealed a non-linear relationship between fiber content and fracture resistance, with 50 % fiber volume fraction yielding optimal performance in terms of both fracture toughness and load-bearing capacity. Notably, a divergence was observed between the trends of break force and fracture toughness, underscoring the importance of evaluating both parameters to fully characterize fracture behavior. To extend the findings beyond the tested configurations, Support Vector Regression (SVR) and Multi-Layer Perceptron (MLP) machine learning models were trained to predict strain energy values for untested fiber volume fractions. Both models demonstrated high predictive accuracy, with MSE values below 1 and R² scores exceeding 0.99. These results provide valuable insights for optimizing fiber-reinforced composite design and highlight the potential of data-driven models in fracture mechanics.

研究了随机取向短切/短纤维增强复合材料的断裂行为与纤维体积分数的关系。采用4mm短切玻璃纤维制作纤维含量分别为0%、20%、30%、40%、50%和60%的复合材料试件，采用三点弯曲试验和验证有限元模型进行I型加载试验。系统考察了纤维体积分数对断裂韧性、断裂力、最大容忍载荷和最大载荷下跨中挠度等关键断裂参数的影响。此外，还计算了裂纹萌生（峰前）和扩展（峰后）过程中吸收的应变能，分析了断裂过程区发育、纤维分布和纤维桥接等增韧机制。结果表明，纤维含量与抗断裂能力之间存在非线性关系，纤维体积分数为50%时，在断裂韧性和承载能力方面都具有最佳性能。值得注意的是，在断裂力和断裂韧性的趋势之间观察到分歧，强调了评估这两个参数以充分表征断裂行为的重要性。为了将研究结果扩展到测试配置之外，我们训练了支持向量回归（SVR）和多层感知器（MLP）机器学习模型，以预测未测试纤维体积分数的应变能值。两种模型均具有较高的预测准确率，MSE值均小于1，R2评分均大于0.99。这些结果为优化纤维增强复合材料设计提供了有价值的见解，并突出了数据驱动模型在断裂力学中的潜力。

{"title":"Fracture behavior of randomly oriented chopped/short fiber-reinforced composite materials: A combined experimental, numerical, and machine learning approach","authors":"Sayed Mohammad Hossein Izadi","doi":"10.1016/j.tafmec.2025.105381","DOIUrl":"10.1016/j.tafmec.2025.105381","url":null,"abstract":"<div><div>This study investigates the fracture behavior of randomly oriented chopped/short fiber-reinforced composite materials as a function of fiber volume fraction. Composite specimens with fiber contents of 0 %, 20 %, 30 %, 40 %, 50 %, and 60 % were fabricated using 4 mm chopped glass fibers and tested under Mode I loading using three-point bending experiments and validated finite element models. The effects of fiber volume fraction on key fracture parameters, including fracture toughness, break force, maximum tolerated load, and mid-span deflection at maximum load, were systematically examined. Additionally, the strain energy absorbed during crack initiation (pre-peak) and propagation (post-peak) was calculated to analyze toughening mechanisms such as fracture process zone development, fiber distribution, and fiber bridging. Results revealed a non-linear relationship between fiber content and fracture resistance, with 50 % fiber volume fraction yielding optimal performance in terms of both fracture toughness and load-bearing capacity. Notably, a divergence was observed between the trends of break force and fracture toughness, underscoring the importance of evaluating both parameters to fully characterize fracture behavior. To extend the findings beyond the tested configurations, Support Vector Regression (SVR) and Multi-Layer Perceptron (MLP) machine learning models were trained to predict strain energy values for untested fiber volume fractions. Both models demonstrated high predictive accuracy, with MSE values below 1 and R<sup>2</sup> scores exceeding 0.99. These results provide valuable insights for optimizing fiber-reinforced composite design and highlight the potential of data-driven models in fracture mechanics.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"142 ","pages":"Article 105381"},"PeriodicalIF":5.6,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145738007","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}

引用次数: 0

Characterization of mixed-mode I/II translaminar fracture in carbon fibre laminates under biaxial loading 双轴载荷下碳纤维层合板I/II混合模式跨层断裂表征

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-03-01 Epub Date: 2025-12-20 DOI: 10.1016/j.tafmec.2025.105419

Yajing Feng , Chang Lei , Jinheng Shi , Youcun Zhao , Ting Zhang , Hao cui

This study investigates the fracture initiation behavior of carbon fibre-reinforced composite laminates under mixed-mode I/II biaxial loading using cruciform specimens with centrally inclined cracks. The combined effects of biaxial load ratio and crack angle were examined by systematically varying both parameters. The fracture energy at crack initiation was quantified using a J-integral–based method coupled with digital image correlation (DIC), and decomposed into Mode I (

J_{1}

) and Mode II (

J_{2}

) components through an energy-based mode partitioning approach. Complementary post-fracture surface analysis and infrared thermography provided further insights into energy dissipation and failure mechanisms. The results reveal that both the total fracture energy (

J_{total}

) and the shear contribution (

J_{2}

) increase with crack angle and biaxial load ratio, indicating a progressive transition from opening- to shear-dominated fracture initiation. The thermographic and morphological observations corroborate the energy decomposition, confirming a strong correspondence between mode mixity evolution and local energy release processes. Based on these findings, a unified fracture energy criterion incorporating explicit dependence on crack angle and load ratio was established. The proposed criterion offers a physically grounded and experimentally supported framework for characterizing mixed-mode fracture initiation in composite laminates under complex multiaxial loading conditions.

采用中心倾斜裂纹的十字形试样，研究了碳纤维增强复合材料层合板在I/II混合模式双轴加载下的起裂行为。通过系统地改变双轴载荷比和裂纹角，考察了两者的联合效应。采用基于j积分的方法结合数字图像相关（DIC）对裂纹起裂时的断裂能进行量化，并通过基于能量的模态划分方法将断裂能分解为I型（J1）和II型（J2）分量。压裂后的附加表面分析和红外热成像为进一步了解能量耗散和破坏机制提供了帮助。结果表明：总断裂能（Jtotal）和剪切贡献（J2）均随着裂纹角度和双轴载荷比的增大而增大，表明断裂起裂方式由开口主导向剪切主导逐步转变；热成像和形态观测证实了能量分解，证实了模态混合演化与局部能量释放过程之间的强烈对应关系。在此基础上，建立了统一的断裂能准则，该准则与裂纹角和载荷比有显式关系。该准则为复杂多轴加载条件下复合材料层合板的混合模式起裂提供了物理基础和实验支持框架。

{"title":"Characterization of mixed-mode I/II translaminar fracture in carbon fibre laminates under biaxial loading","authors":"Yajing Feng , Chang Lei , Jinheng Shi , Youcun Zhao , Ting Zhang , Hao cui","doi":"10.1016/j.tafmec.2025.105419","DOIUrl":"10.1016/j.tafmec.2025.105419","url":null,"abstract":"<div><div>This study investigates the fracture initiation behavior of carbon fibre-reinforced composite laminates under mixed-mode I/II biaxial loading using cruciform specimens with centrally inclined cracks. The combined effects of biaxial load ratio and crack angle were examined by systematically varying both parameters. The fracture energy at crack initiation was quantified using a J-integral–based method coupled with digital image correlation (DIC), and decomposed into Mode I (<span><math><msub><mi>J</mi><mn>1</mn></msub></math></span>) and Mode II (<span><math><msub><mi>J</mi><mn>2</mn></msub></math></span>) components through an energy-based mode partitioning approach. Complementary post-fracture surface analysis and infrared thermography provided further insights into energy dissipation and failure mechanisms. The results reveal that both the total fracture energy (<span><math><msub><mi>J</mi><mi>total</mi></msub></math></span>) and the shear contribution (<span><math><msub><mi>J</mi><mn>2</mn></msub></math></span>) increase with crack angle and biaxial load ratio, indicating a progressive transition from opening- to shear-dominated fracture initiation. The thermographic and morphological observations corroborate the energy decomposition, confirming a strong correspondence between mode mixity evolution and local energy release processes. Based on these findings, a unified fracture energy criterion incorporating explicit dependence on crack angle and load ratio was established. The proposed criterion offers a physically grounded and experimentally supported framework for characterizing mixed-mode fracture initiation in composite laminates under complex multiaxial loading conditions.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"142 ","pages":"Article 105419"},"PeriodicalIF":5.6,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840449","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}

引用次数: 0

A critical assessment of J-integral and CBBM validity in fracture characterization of brittle, ductile, and flexible adhesives j积分和CBBM在脆性、韧性和柔性胶粘剂断裂表征中的有效性的关键评估

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-03-01 Epub Date: 2025-12-17 DOI: 10.1016/j.tafmec.2025.105395

B.G.A. Reket , A. Akhavan-Safar , B. Hasumi , M. Ferreira , B.D. Simões , V.C.M.B. Rodrigues , R.J.C. Carbas , E.A.S. Marques , O. van der Sluis , L.F.M. da Silva

Fracture characterization methods across adhesives from brittle to highly ductile reveals critical inconsistencies in widely accepted approaches, namely J-integral and Compliance-Based Beam Method (CBBM). While both methods are generally considered acceptable for fracture analysis across various adhesive types, this work demonstrates that such assumptions can be misleading and potentially unsafe. Using Double Cantilever Beam (DCB) specimens, the fracture energy during crack propagation was evaluated for each method. The results reveal a previously underexplored limitation: both methods exhibit major discrepancies when applied to adhesives with significant plasticity, with fracture energy differences reaching up to 50%, and even higher for highly flexible systems. Critically, the study shows that the use of an inappropriate data reduction method can significantly overestimate or underestimate fracture energy, potentially leading to over-conservative or dangerously non-conservative joint designs. Despite being based on linear elastic fracture mechanics (LEFM), CBBM consistently outperformed the more general J-integral by producing equivalent crack lengths that closely reflect the effect of fracture process zone. In contrast, the J-integral method was found to underestimate fracture energy in highly ductile adhesives due to its inability to capture the full extent of the plastic zone. This work is the first to quantitatively demonstrate these risks and method-dependent inaccuracies across a wide range of adhesive systems, providing a clear recommendation for CBBM in cases of highly ductile and flexible adhesives. These findings offer important practical guidance for researchers and engineers seeking reliable fracture characterization in the design of adhesively bonded structures.

从脆性到高延性胶粘剂的断裂表征方法揭示了广泛接受的方法（即j积分和基于柔度的梁法（CBBM））的严重不一致性。虽然这两种方法通常被认为是可以接受的，但这项工作表明，这种假设可能会产生误导，并且可能不安全。采用双悬臂梁（DCB）试件，对两种方法在裂纹扩展过程中的断裂能进行了计算。结果揭示了以前未被充分开发的局限性：当应用于具有显著塑性的粘合剂时，两种方法都表现出很大的差异，断裂能差异可达50%，对于高度柔性的系统甚至更高。至关重要的是，该研究表明，使用不适当的数据简化方法可能会严重高估或低估裂缝能量，从而可能导致过度保守或危险的非保守关节设计。尽管CBBM是基于线弹性断裂力学（LEFM），但它产生的等效裂纹长度更能反映断裂过程带的影响，从而优于更一般的j积分。相比之下，j积分法被发现低估了高延性胶粘剂的断裂能，因为它无法捕捉塑性区的全部范围。这项工作是第一次在广泛的粘合剂系统中定量地证明这些风险和方法相关的不准确性，为高延展性和柔性粘合剂的CBBM提供了明确的建议。这些发现为研究人员和工程师在粘连结构设计中寻求可靠的断裂特征提供了重要的实用指导。

{"title":"A critical assessment of J-integral and CBBM validity in fracture characterization of brittle, ductile, and flexible adhesives","authors":"B.G.A. Reket , A. Akhavan-Safar , B. Hasumi , M. Ferreira , B.D. Simões , V.C.M.B. Rodrigues , R.J.C. Carbas , E.A.S. Marques , O. van der Sluis , L.F.M. da Silva","doi":"10.1016/j.tafmec.2025.105395","DOIUrl":"10.1016/j.tafmec.2025.105395","url":null,"abstract":"<div><div>Fracture characterization methods across adhesives from brittle to highly ductile reveals critical inconsistencies in widely accepted approaches, namely J-integral and Compliance-Based Beam Method (CBBM). While both methods are generally considered acceptable for fracture analysis across various adhesive types, this work demonstrates that such assumptions can be misleading and potentially unsafe. Using Double Cantilever Beam (DCB) specimens, the fracture energy during crack propagation was evaluated for each method. The results reveal a previously underexplored limitation: both methods exhibit major discrepancies when applied to adhesives with significant plasticity, with fracture energy differences reaching up to 50%, and even higher for highly flexible systems. Critically, the study shows that the use of an inappropriate data reduction method can significantly overestimate or underestimate fracture energy, potentially leading to over-conservative or dangerously non-conservative joint designs. Despite being based on linear elastic fracture mechanics (LEFM), CBBM consistently outperformed the more general J-integral by producing equivalent crack lengths that closely reflect the effect of fracture process zone. In contrast, the J-integral method was found to underestimate fracture energy in highly ductile adhesives due to its inability to capture the full extent of the plastic zone. This work is the first to quantitatively demonstrate these risks and method-dependent inaccuracies across a wide range of adhesive systems, providing a clear recommendation for CBBM in cases of highly ductile and flexible adhesives. These findings offer important practical guidance for researchers and engineers seeking reliable fracture characterization in the design of adhesively bonded structures.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"142 ","pages":"Article 105395"},"PeriodicalIF":5.6,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790872","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}

引用次数: 0