Theoretical and Applied Fracture Mechanics最新文献_第6页

Cross-scale crack evolution in pre-flawed sandstone under high temperature: Insights from a composition-aware thermal-mechanical grain-based model 高温下预缺陷砂岩的跨尺度裂纹演化：基于成分感知的热-力学颗粒模型的启示

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-01-06 DOI: 10.1016/j.tafmec.2026.105450

Shi Liu , Zhipeng Zhang , Qixing Wu , Chun Feng , Chen Chen , Xiasong Hu

In deep energy extraction, thermal damage induced by high temperatures critically degrades the mechanical integrity of rock, posing substantial risks to engineering safety. To systematically clarify the damage mechanisms under coupled thermal-mechanical-fracture conditions, this study develops a novel Composition-Aware Thermal-Mechanical Grain-Based Model (CATM-GBM).This model explicitly integrates the rock's quantitative mineralogical composition and spatial heterogeneity, implementing a temperature-dependent thermal expansion function to capture differential mineral degradation and employing parallel bond model and smooth joint model to simulate intergranular tensile and intragranular shear failure modes. Results demonstrate pronounced mechanical degradation under high-temperature exposure, characterized by marked reductions in uniaxial compressive strength and elastic modulus, significant increases in peak axial strain, and a coherent transition from brittle to ductile post-peak behavior. Crack analysis reveals tensile-dominated failure throughout loading and identifies a critical transition near 500 °C: intergranular cracking prevails below this threshold, while intragranular cracking dominates above it due to intensified thermal mismatch stresses and micro-damage within mineral grains. Pre-existing flaws control macroscopic failure patterns, promoting through-going “X”-shaped conjugate shear bands in flawed specimens, in contrast to localized “V”-shaped failures in intact ones. Microscopically, deviatoric loading induces particle-scale anisotropy, triggering progressive grain rotation, slip, and contact network destabilization. Macroscopically, cracks initiate predominantly at flaw tips and propagate to form specimen-scale through-fractures. This research provides a systematic, multi-scale decoupling of thermal cracking evolution in fractured sandstone, establishing a robust predictive numerical framework for assessing thermomechanical stability in critical deep geological engineering applications, including enhanced geothermal systems and deep geological repositories for nuclear waste.

在深部能源开采中，高温引起的热损伤严重降低了岩石的力学完整性，给工程安全带来了重大风险。为了系统地阐明热-力学-断裂耦合条件下的损伤机制，本研究建立了一种新的基于成分感知的热-力学晶粒模型（CATM-GBM）。该模型明确地整合了岩石的定量矿物组成和空间非均质性，实现了温度相关的热膨胀函数来捕捉矿物的差异降解，并采用平行键合模型和光滑节理模型来模拟粒间拉伸和粒内剪切破坏模式。结果表明，高温暴露下的机械退化明显，其特征是单轴抗压强度和弹性模量显著降低，峰值轴向应变显著增加，峰后行为从脆性到延性的一致转变。裂纹分析揭示了整个加载过程中以拉伸为主的破坏，并确定了在500°C附近的临界转变：在此阈值以下，晶间裂纹普遍存在，而在此阈值以上，由于热失配应力和矿物颗粒内的微损伤加剧，晶内裂纹主要存在。预先存在的缺陷控制着宏观破坏模式，在缺陷试件中促进贯通的“X”形共轭剪切带，而在完整试件中则是局部的“V”形破坏。微观上，偏载引起颗粒尺度的各向异性，引发颗粒的逐渐旋转、滑移和接触网络的不稳定。宏观上，裂纹主要在裂纹尖端起裂并扩展形成试样尺度的贯通断裂。该研究为裂缝性砂岩的热裂解演化提供了系统的、多尺度的解耦，为评估关键深层地质工程应用（包括增强型地热系统和核废料深层地质储存库）的热力学稳定性建立了一个强大的预测数值框架。

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引用次数: 0

Integrity conditions of К-220-44-2М and К-325-23.5 turbine shafts at a short circuit on a turbogenerator in the presence of crack 汽轮发电机К-220-44-2М和К-325-23.5轴在裂纹存在下短路时的完整性条件

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-01-06 DOI: 10.1016/j.tafmec.2026.105447

A. Bovsunovsky , M. Borodii , O. Bovsunovsky

Catastrophic failures of steam turbines, which occurred in the history of thermal power engineering, were caused by the long-term accumulation of fatigue damage and sudden application of dynamic torque. The dynamic torque is the result of abnormal operating modes of a turbogenerator at the connection of turbogenerator to the power network with an inaccurate synchronization, as well as at short circuit on a turbogenerator. So, this a real engineering problem. Under certain conditions, such a load causes intense torsional vibrations of the turbine shaft, sufficient for its disintegration in condition of crack presence. Given the problem, the method to estimate the critically dangerous sizes of circular, transverse and longitudinal crack, at which a short circuit on a turbogenerator will lead to the disintegration of the turbine shaft, has been created. The method was applied to estimate the critically dangerous size of crack in K-220-44-2 M and K-325-23.5 turbine shafts. It was based on the dynamic torques in the most stressed sections of the turbine shafts because of a short circuit. The crack for which the stress intensity factor reaches the fracture toughness of the rotor steel is considered as critically dangerous. It is assumed that such a crack will lead to disintegration of the shaft because of a short circuit. Using the method, the critical size of circular, transverse and longitudinal crack in K-220-44-2 M and K-325-23.5 turbine shafts were determined in a certain range of the rotor steel fracture toughness.

在火电工程发展史上，汽轮机的灾难性故障是由于疲劳损伤的长期积累和动态扭矩的突然施加造成的。动态转矩是汽轮发电机与电网连接时同步不准确，以及汽轮发电机短路时异常运行模式的结果。这是一个真正的工程问题。在某些条件下，这样的载荷会引起涡轮轴强烈的扭转振动，足以使其在裂纹存在的情况下解体。针对这一问题，建立了汽轮发电机组短路时引起汽轮机轴断裂的圆形、横向和纵向裂纹临界危险尺寸的估计方法。将该方法应用于K-220-44-2 M和K-325-23.5涡轮轴裂纹临界危险尺寸的估计。它是基于在涡轮轴的最受力部分的动态扭矩，因为短路。应力强度因子达到转子钢断裂韧性的裂纹被认为是临界危险裂纹。假定这样的裂缝会由于短路而导致轴的解体。利用该方法确定了K-220-44-2 M和K-325-23.5涡轮轴在转子钢断裂韧性一定范围内的圆形、横向和纵向裂纹的临界尺寸。

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引用次数: 0

Crack evolution in salt rock with a prefabricated flaw under uniaxial compression: Insights from coupled AE and DIC monitoring 含预制裂纹的盐岩单轴压缩裂纹演化：声发射与DIC耦合监测的启示

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-01-06 DOI: 10.1016/j.tafmec.2026.105449

Mingtian Zhang , Jinyang Fan , Mengying Luan , Jie Chen , Deyi Jiang , Yifan Wang , Dan Lu , Zongze Li , Daniel Nelias

Salt rock is widely recognized as an ideal host medium for underground energy storage and radioactive-waste disposal. Nevertheless, the presence of fractures within salt cavern gas storage can markedly compromise the integrity of the surrounding rock mass. Focusing on the mechanisms of fracture evolution and mechanical response in salt rock, this study conducted uniaxial compressive strength (UCS) tests on cubic salt specimens containing prefabricated flaws at various inclinations. Acoustic Emission (AE) monitoring and Digital Image Correlation (DIC) were integrated to capture the damage development and crack evolution in real time. The results show that: (1) Flaw inclination exerts a significant effect on both the UCS and the crack-propagation path of salt rock, exhibiting a clear and reproducible angle effect. (2) DIC effectively captures orientation-dependent crack trajectories, revealing the geometric complexity of surface crack evolution during failure. (3) According to the RA-AF criterion, the tensile-event fraction ranks 90° > 0° > 45° > 30° > 60°, consistent with the DIC observations and energy-index analysis. (4) The fractal dimension D increases over time, indicating progressive network densification and multiscale damage amplification. (5) The spatiotemporal distribution of AE events exhibits a damage-localization trend consistent with the evolution of the DIC principal strain field, confirming the complementary capabilities of the two monitoring techniques. The results provide a solid experimental basis for the quantitative evaluation of inclination effects and for the stability assessment of salt cavern storage, offering practical guidance for cavern design and long-term performance appraisal.

盐岩被广泛认为是地下能量储存和放射性废物处理的理想宿主介质。然而，盐穴储气库中裂缝的存在会明显损害围岩的完整性。针对盐岩断裂演化与力学响应机制，对不同倾角预制缺陷的立方盐试件进行了单轴抗压强度试验。将声发射（AE）监测和数字图像相关（DIC）技术相结合，实时捕捉损伤发展和裂纹演化过程。结果表明：(1)缺陷倾斜度对盐岩单轴载荷和裂纹扩展路径均有显著影响，且角度效应明显且可重现；(2) DIC有效捕获了与方向相关的裂纹轨迹，揭示了破坏过程中表面裂纹演化的几何复杂性。(3)根据RA-AF准则，拉伸事件分数为90°>； 0°> 45°> 30°> 60°，与DIC观测结果和能量指数分析一致。(4)分形维数D随时间增大，表明网络逐渐致密化，多尺度损伤放大。(5)声发射事件的时空分布表现出与DIC主应变场演化一致的损伤局部化趋势，证实了两种监测技术的互补性。研究结果为倾斜度定量评价和盐洞库稳定性评价提供了坚实的实验依据，为盐洞库设计和长期性能评价提供了实践指导。

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引用次数: 0

Peridynamic modeling of ballistic impact on metallic-ceramic functionally graded Sandwich plates 金属-陶瓷功能梯度夹层板弹道冲击的周动力学建模

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-01-02 DOI: 10.1016/j.tafmec.2026.105435

Ioannis Sioutis, Konstantinos Tserpes

Functionally Graded Sandwich Plates (FGSP) composed of metallic-ceramic layers have been widely investigated for their superior ballistic performance. Their through-the-thickness variation in material properties significantly enhances energy dissipation and resistance to projectile penetration. While traditional numerical FEA tools such as LS-Dyna can simulate such phenomena with reasonable accuracy, the non-local method of peridynamics (PD) offers a promising alternative for capturing complex fracture and failure mechanisms, particularly under dynamic loading. To the authors' best knowledge, direct comparison of the two methods in computational terms on an actual case study has been lacking from literature. In the present article, the ballistic impact of a 0.30 caliber steel projectile to a 7-layer Al-SiC composite FGSP is numerically examined using a bond-based PD framework. Although LS-Dyna was initially selected for both FEA and PD simulations, limitations of the available PD implementation necessitated the adaptation of LAMMPS molecular dynamics simulator to accommodate a fully customized bond-based PD model. A comprehensive parametric study was performed, including variations in lattice discretization, horizon radius and material inhomogeneity, to assess the accuracy and robustness of the PD approach. Comparative analysis against conventional FEA results is presented, highlighting the strengths and limitations of each method in predicting impact response, failure modes and damage evolution. The results demonstrate that the PD method provides enhanced resolution of fracture phenomena, offering valuable insights into the design of advanced FGSPs in ballistic protection applications.

由金属陶瓷层组成的功能梯度夹层板（FGSP）因其优异的弹道性能而受到广泛的研究。它们的材料性能随厚度的变化显著提高了能量耗散和抗弹丸侵彻能力。传统的数值有限元分析工具，如LS-Dyna，可以以合理的精度模拟这种现象，而非局部周动力学（PD）方法为捕获复杂的断裂和破坏机制，特别是在动态载荷下，提供了一种有希望的替代方法。据作者所知，文献中缺乏对这两种方法在计算方面的实际案例研究的直接比较。在本文中，使用基于键合的PD框架对0.30口径钢弹丸对7层Al-SiC复合材料FGSP的弹道冲击进行了数值研究。虽然LS-Dyna最初被选择用于FEA和PD模拟，但现有PD实现的局限性使得LAMMPS分子动力学模拟器必须适应完全定制的基于键的PD模型。进行了全面的参数研究，包括晶格离散化，水平半径和材料不均匀性的变化，以评估PD方法的准确性和鲁棒性。通过与传统有限元分析结果的对比分析，突出了每种方法在预测冲击响应、破坏模式和损伤演化方面的优势和局限性。结果表明，PD方法提高了断裂现象的分辨率，为弹道防护应用中先进FGSPs的设计提供了有价值的见解。

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引用次数: 0

Mixed-mode(I/II) fracture behaviour and criterion-based analysis of banana fiber reinforced epoxy composites using asymmetric SCB specimens 香蕉纤维增强环氧复合材料的I/II混合模式断裂行为及基于准则的非对称SCB试样分析

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-01-02 DOI: 10.1016/j.tafmec.2025.105433

L.C. Shashidhar , Saravanabavan , Rajeev Kumar Gupta , S.C. Ramesh Kumar , R. Vara Prasad Kaviti , M.A. Umarfarooq , Vinayak S. Uppin , B.H. Maruthi Prashanth

This work investigates the mixed-mode (I/II) fracture behaviour of banana fiber-reinforced epoxy composite using asymmetric semi-circular bend (ASCB) specimens. Laminates were fabricated via hand layup-assisted vacuum bag moulding, with banana fibers integrated into an epoxy matrix. Three-point bending tests were conducted on ASCB specimens (radius 60 mm, thickness 6 mm, and notch length 30 mm) under varying asymmetric support spans (40–40 mm to 40–20 mm) to transition from pure mode I to mixed-mode I/II loading. Results showed a non-monotonic mode I fracture toughness (K_I) trend (1.70 MPa.m^1/2 decreasing to 1.54 MPa.m^1/2, then increasing to 1.92 MPa.m^1/2) and rising mode II fracture toughness (K_II) (0.30 to 0.87 MPa.m^1/2) with increasing mode II contribution, attributed to fiber-matrix interactions.

Experimental results were compared with analytical predictions based on the Power Law, maximum tangential stress (MTS), generalised maximum tangential stress (GMTS), and maximum energy release rate (Gmax) criteria. The Power Law criterion underestimated fracture resistance failing to capture constraint effects and fiber-related toughening. Incorporation of T-stress in the MTS and GMTS models improved predictions, though both overestimated crack initiation angles. Among the compared criteria, Gmax provided the closest correlation with crack initiation angles (0° to −17.26°), highlighting its suitability for natural fiber composites. Overall, the findings reveal a strong dependence of mixed-mode fracture behaviour on fiber-matrix interaction mechanisms, confirming the suitability of energy-based criteria for accurately modelling the fracture response of anisotropic natural fiber composites.

本文采用非对称半圆弯曲（ASCB）试样研究了香蕉纤维增强环氧复合材料的混合模式（I/II）断裂行为。层压板是通过手工分层辅助真空袋成型制造的，香蕉纤维集成到环氧树脂基体中。对ASCB试件（半径60 mm，厚度6 mm，缺口长度30 mm）在不同的非对称支承跨度（40-40 mm ~ 40-20 mm）下进行了由纯I型加载过渡到混合I/II型加载的三点弯曲试验。结果表明，断裂韧性呈非单调I型（1.70 MPa）趋势。m1/2减小到1.54 MPa。m1/2，然后增加到1.92 MPa。m1/2)， II型断裂韧性（KII）上升（0.30 ~ 0.87 MPa）。m1/2)，模式II贡献增加，归因于纤维-基质相互作用。实验结果与基于幂律、最大切向应力（MTS）、广义最大切向应力（GMTS）和最大能量释放率（Gmax）准则的分析预测结果进行了比较。幂律准则低估了断裂抗力，未能捕捉到约束效应和纤维相关的增韧。在MTS和GMTS模型中加入t应力改进了预测，尽管两者都高估了裂纹起裂角。其中，Gmax与裂纹起裂角（0°~ - 17.26°）的相关性最密切，突出了其对天然纤维复合材料的适用性。总的来说，研究结果揭示了混合模式断裂行为对纤维-基质相互作用机制的强烈依赖，证实了基于能量的标准准确模拟各向异性天然纤维复合材料断裂响应的适用性。

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引用次数: 0

Failure modes and energy evolution of jointed rock mass with holes under high temperature and fatigue loading 高温疲劳载荷下节理岩体孔洞破坏模式及能量演化

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2026-01-02 DOI: 10.1016/j.tafmec.2025.105434

Piaopiao Tan , Fenghua Nie, Zeyue Wang , Yi Tang , Hang Lin

Deep-buried tunnel construction is greatly influenced by high ground stress, temperature, and inevitable joint defects in the surrounding geology. This study investigates the effects of high temperature on the mechanical behavior and failure characteristics of red sandstone with combined far-field joints and horseshoe-shaped holes, simulating deep-buried tunnel conditions. Samples were heat-treated at various high temperature ranges and subjected to uniaxial compression and cyclic loading tests, with simultaneous acoustic emission (AE) and digital image correlation (DIC) monitoring. Results show that peak stress and fatigue failure stress increase then decrease with temperature, peaking at 600 °C, while elastic modulus sharply declines above this temperature. Thermal damage promotes microcrack development and alters deformation stages, increasing compaction and residual strain during fatigue loading, but does not significantly change failure modes. However, thermal damage had little effect on the failure mode of the specimens. The penetration of the rectangular side rock bridge of the hole precedes that of the circular side rock bridge, and both penetrations are located at the arch waist of the hole. Failure is dominated by shear cracks extending from joint tips, guided by far-field joints. Analyzing the energy evolution under fatigue loading, a novel quadratic model is proposed to predict the elastic energy density at failure, outperforming traditional linear models, especially under complex loading cycles. This study offers new insights into the damage evolution of rock masses under high ground stress and temperature conditions, contributing to the improved design and safety of deep-buried tunnel construction.

深埋隧道施工受高地应力、高温度和周围地质中不可避免的节理缺陷的影响较大。模拟深埋隧道条件，研究了高温对远场节理与马蹄形孔洞组合红砂岩力学行为及破坏特征的影响。在不同的高温范围内对样品进行热处理，并进行单轴压缩和循环加载试验，同时进行声发射（AE）和数字图像相关（DIC）监测。结果表明，峰值应力和疲劳破坏应力随温度的升高先增大后减小，在600℃达到峰值，而弹性模量在600℃以上急剧下降。热损伤促进微裂纹发展，改变变形阶段，增加疲劳加载过程中的压实和残余应变，但不显著改变破坏模式。热损伤对试件的破坏模式影响不大。孔内矩形侧岩桥的贯通先于圆形侧岩桥，且均位于孔拱腰处。破坏主要是由远场节理引导的从节理尖端延伸的剪切裂纹。分析了疲劳载荷下的能量演化，提出了一种新的二次模型来预测失效时的弹性能量密度，优于传统的线性模型，特别是在复杂载荷循环下。该研究为高地应力和高温度条件下岩体的损伤演化提供了新的认识，有助于改进深埋隧道施工的设计和安全性。

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引用次数: 0

Fracture characteristics and energy catastrophe properties of sandstone with the circular hole: The influence of different inclusions 含圆孔砂岩断裂特征及能量突变特性：不同包裹体的影响

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2025-12-31 DOI: 10.1016/j.tafmec.2025.105430

Kai Zhang , Guowei Ma , Ke Zhang

Holes, as the common defects in rock masses, are often accompanied by natural or artificial inclusions, which further complicate the failure mechanisms. To study the fracture mechanisms of sandstone with the circular hole under various filling conditions, uniaxial compression tests are conducted on three types of specimens. Combined with digital image correlation (DIC) and energy evolution theory, the mechanical degradation, crack propagation, spatial and temporal non-uniformity of deformation, and energy catastrophe characteristics are analyzed. The results show that the presence of the hole significantly degrades the mechanical properties of sandstone, with the uniaxial compressive strength (UCS) and elastic modulus (E) reduced by approximately 34.08 % and 21.03 %, respectively, compared with intact specimens. Inclusion filling partially restores the mechanical performance: soft inclusion increases the UCS and E by about 8.50 % and 14.17 %, whereas hard inclusion leads to more pronounced improvements of approximately 12.48 % and 19.87 %, respectively. The crack evolution patterns vary considerably with the filling condition: unfilled specimen experience tensile crack initiation followed by tensile-shear transition leading to shear-dominated failure; soft inclusions delay crack propagation and promote interface-controlled ductile failure; hard inclusions accumulate internal cracks, resulting in more abrupt and brittle instability. The proposed spatial and temporal non-uniformity indicators (I_S and I_T), derived from DIC data, effectively characterize the evolution of strain localization and identify the transition from stable fracture to unstable fracture. Moreover, the developed grey cusp catastrophe model based on elastic and dissipated strain energy density evolutions successfully captures abrupt changes in energy evolution, providing reliable physical interpretation and validation for the instability trends revealed by I_S and I_T.

孔洞作为岩体中常见的缺陷，常伴有天然或人工包裹体，使其破坏机制更加复杂。为研究不同充填条件下圆孔砂岩的破裂机理，对三种试件进行了单轴压缩试验。结合数字图像相关（DIC）和能量演化理论，分析了材料的力学退化、裂纹扩展、变形时空不均匀性和能量突变特征。结果表明，孔洞的存在显著降低了砂岩的力学性能，单轴抗压强度（UCS）和弹性模量(E)分别比完整试件降低了约34.08%和21.03%。包裹体填充部分恢复了合金的力学性能：软包裹体的UCS和E分别提高了8.50%和14.17%，而硬包裹体的UCS和E分别提高了12.48%和19.87%。不同充填条件下，裂隙演化模式差异较大：未充填试样先经历拉伸裂纹萌生，然后经历拉剪转变，最终形成剪切为主破坏；软夹杂物延缓裂纹扩展，促进界面可控延性破坏；硬夹杂物在裂纹内部堆积，导致脆性脆性失稳。本文提出的时空非均匀性指标（IS和IT）来源于DIC数据，可以有效表征应变局部化的演化过程，识别从稳定骨折到不稳定骨折的转变。此外，建立的基于弹性和耗散应变能密度演化的灰尖突变模型成功捕获了能量演化的突变，为IS和IT揭示的不稳定趋势提供了可靠的物理解释和验证。

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引用次数: 0

Assessing fracture characteristics of high-performance fiber-reinforced concrete using notched flexural specimens 用缺口弯曲试件评估高性能纤维增强混凝土的断裂特性

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2025-12-31 DOI: 10.1016/j.tafmec.2025.105427

Duy-Liem Nguyen , Tan-Khoa Nguyen , Kha-Ky Lam , Duc-Kien Thai , Ngoc-Thanh Tran

The fracture characteristics of high-performance fiber-reinforced concrete (HPFRC) using notched flexural specimens were assessed under both static and repeated loads. There were three HPFRC mixtures examined: HPFRC0 (without fibers), HPFRC1 (containing 1.0 vol% hooked and 0.5 vol% smooth steel fibers), and HPFRC2 (with 0.5 vol% hooked and 1.0 vol% short steel fibers). All test specimens were rectangular prisms measuring 40 × 40 × 160 mm³. Four notch depths, including 0, 5, 10, and 15 mm, were applied to each mix design. All flexural specimens were rectangular prisms with dimensions of 40 × 40 × 160 mm³. The specimens were evaluated under a three-point bending (3 PB) configuration with a span length of 120 mm. The results indicate that the hardening fracture energy of all HPFRCs decreased with notch depth under static flexural loading. The total fracture energy and length of cohesive zone were greatest at a notch depth of 0 mm for HPFRC0, and at a notch depth of 10 mm for both HPFRC1 and HPFRC2. When subjected to repeated loading, specimens with a 5-mm notch exhibited the highest fatigue energy per cycle across all HPFRC types. Additionally, at a constant fatigue energy per cycle, increasing the notch depth led to a longer fatigue life.

采用缺口抗弯试件对高性能纤维混凝土（HPFRC）在静载荷和重复载荷作用下的断裂特性进行了研究。研究了三种HPFRC混合物：HPFRC0（不含纤维）、HPFRC1（含1.0卷%钩状钢纤维和0.5卷%光滑钢纤维）和HPFRC2（含0.5卷%钩状钢纤维和1.0卷%短钢纤维）。所有试件均为矩形棱镜，尺寸为40 × 40 × 160 mm3。每种混合设计采用4种缺口深度，包括0、5、10和15 mm。所有试件均为矩形棱镜，尺寸为40 × 40 × 160 mm3。试件在跨度为120 mm的三点弯曲（3pb）配置下进行了评估。结果表明：在静态弯曲载荷作用下，所有HPFRCs的硬化断裂能随缺口深度的增加而减小；缺口深度为0 mm时，HPFRC0的总断裂能和黏结区长度最大，缺口深度为10 mm时，HPFRC1和HPFRC2的断裂能和黏结区长度最大。当重复加载时，在所有HPFRC类型中，具有5mm缺口的试件每循环表现出最高的疲劳能量。此外，在一定的循环疲劳能量下，增加缺口深度可以延长疲劳寿命。

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引用次数: 0

Enhancing interlaminar fracture toughness of carbon fiber/epoxy resin composite by interleaving polyvinylidene fluoride electrospun beaded fiber membranes 聚偏氟乙烯静电纺丝珠状纤维膜交织增强碳纤维/环氧树脂复合材料的层间断裂韧性

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2025-12-30 DOI: 10.1016/j.tafmec.2025.105432

Fei Wang , Chuanguo Ma , Liaoxian Wei , Yuqi Liu , Shaoning Lu

Electrospun nanofiber membranes are promising interlayer toughening materials for carbon fiber/epoxy (CF/EP) composites. However, the simple control of their morphology to achieve a significant interlaminar toughening effect remains a relatively underexplored area. Herein, polyvinylidene fluoride (PVDF) electrospun membranes were successfully prepared through solvent regulation of N, N-dimethylformamide/acetone (DMF/ACE) ratios. Controlled morphological evolution was accomplished through the systematic increase of the DMF fraction from 0.6 to 1.0. Smooth large-diameter fibers underwent a transition to bead-on-string architectures, with the bead density increasing gradually and the fiber diameter decreasing. This trend reached its peak at a DMF:ACE ratio of 9:1. This optimized structure enhanced the mode I fracture toughness of CF/EP laminates to 1.08 ± 0.04 kJ·m⁻², representing 116 % improvements over unmodified laminates. Crack deflection by beads, interfacial bead pull-out, and constrained fiber bridging were identified as dominant toughening mechanisms. Cohesive zone modeling simulations further validated a 74.7 % interfacial strength enhancement without stiffness compromise. This solvent-regulation strategy provides a new perspective on the application of electrospun fiber membranes in the interlaminar toughening of CF/EP composites.

静电纺丝纳米纤维膜是碳纤维/环氧树脂（CF/EP）复合材料中很有前途的层间增韧材料。然而，简单地控制它们的形态以达到显著的层间增韧效果仍然是一个相对欠发达的领域。通过溶剂调节N， N-二甲基甲酰胺/丙酮（DMF/ACE）的比例，成功制备了聚偏氟乙烯（PVDF）静电纺丝膜。通过系统地将DMF分数从0.6增加到1.0，实现了受控的形态进化。光滑大直径光纤由珠串结构过渡到珠串结构，珠密度逐渐增大，纤维直径逐渐减小。这一趋势在DMF:ACE比率为9:1时达到顶峰。优化后的结构使CF/EP层压板的I型断裂韧性提高到1.08±0.04 kJ·m−2，比未改性的层压板提高了116%。裂纹挠曲由珠，界面珠拉出，和约束纤维桥接被确定为主要的增韧机制。内聚区模拟进一步验证了在不降低刚度的情况下界面强度提高74.7%。这种溶剂调节策略为静电纺丝纤维膜在CF/EP复合材料层间增韧中的应用提供了新的前景。

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引用次数: 0

Numerical modeling of three-dimensional quasi-brittle fracture and machining-induced damage in orthotropic composites 正交异性复合材料三维准脆性断裂及加工损伤的数值模拟

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics

Pub Date : 2025-12-30 DOI: 10.1016/j.tafmec.2025.105415

Pawan Kumar , Anil Meena , Shantanu S. Mulay

This study examines three-dimensional (3D) orthogonal machining-induced fracture in carbon/epoxy composites using a continuum damage mechanics (CDM) model. The model, based on Hashin’s 3D failure theory with a linear softening law, is implemented as VUMAT subroutine in the explicit ABAQUS® framework to capture failure initiation and damage evolution. Validation against numerical benchmarks and experimental data — through lamina patch tests and predicted crack paths in both lamina and laminates — demonstrate the model robustness. It successfully reproduces crack nucleation, branching, arrest, and intra/interlaminar failures typical of composite fracture. Orthogonal machining simulations are conducted for lamina with varying fiber orientations and for laminates of different layups. Localized 3D stress analysis near the tool tip revealed the mechanisms driving subsurface fracture and 3D chip formation. In 0° plies, fracture is dominated by fiber compression and matrix crushing under longitudinal compression and in-plane shear, with minimal subsurface damage. At 45° and 90°, shearing and fiber–matrix debonding prevail under combined shear and transverse stresses, while 135° ply exhibits the most severe subsurface damage due to fiber bending and interfacial debonding. For laminates (symmetric, antisymmetric, unsymmetric, and cross-ply), fracture patterns are strongly orientation-dependent. Plies at 45°, 60°, and

- 120 °

promote the chip flow along the fiber directions, while the plies at

- 45 °

and 120° fracture perpendicular to the fibers due to fiber–rake interactions. Subsurface damage depends on the ply location, with the outer 45° and 60° plies showing the highest susceptibility. However, cross-ply laminates exhibit the least damage owing to favorable stress redistribution. This study thus successfully reveals the mechanics of 3D crack propagation in composites subjected to orthogonal machining that can also be extended to other loadings.

本研究使用连续损伤力学（CDM）模型研究了碳/环氧复合材料的三维（3D）正交加工诱导断裂。该模型基于Hashin的三维失效理论，具有线性软化定律，在显式ABAQUS®框架中作为VUMAT子程序实现，以捕获失效起始和损伤演化。对数值基准和实验数据的验证-通过层板贴片测试和预测层板和层板的裂纹路径-证明了模型的鲁棒性。它成功地再现了复合断裂典型的裂纹成核、分支、止裂和层内/层间破坏。对不同纤维取向的层板和不同铺层的层板进行了正交加工仿真。工具尖端附近的局部三维应力分析揭示了驱动地下断裂和三维切屑形成的机制。在0°层段，纵向压缩和面内剪切作用下，断裂以纤维压缩和基质破碎为主，次表面损伤最小。在45°和90°处，剪切和纤维-基体脱粘在剪切和横向复合应力下普遍存在，而135°处由于纤维弯曲和界面脱粘而表现出最严重的亚表面损伤。对于层压板（对称、反对称、不对称和交叉铺层），断裂模式强烈依赖于方向。45°、60°和- 120°的层叠层促进了切屑沿纤维方向流动，而- 45°和120°的层叠层由于纤维-耙的相互作用而垂直于纤维断裂。亚表面损伤取决于层的位置，外部45°和60°层表现出最高的敏感性。然而，由于有利的应力重新分布，交叉层合板表现出最小的损伤。因此，该研究成功地揭示了正交加工复合材料中三维裂纹扩展的力学，也可以扩展到其他载荷。

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引用次数: 0