Engineering Fracture Mechanics最新文献_第2页

A novel mesh-fragmentation-based mesoscale approach for modeling compressive fracture in concrete with application to recycled aggregate concrete 基于网格碎片的混凝土压缩断裂细观尺度模拟方法及其在再生骨料混凝土中的应用

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2026-01-24 DOI: 10.1016/j.engfracmech.2026.111893

Marcela Gimenes, Osvaldo L. Manzoli

The internal structure of concrete consists of aggregates, cement mortar, and weak interfaces distributed at the mesoscopic level, which strongly influence its quasi-brittle mechanical behavior. Recycled aggregate concrete (RAC) presents an even more heterogeneous mesostructure, making the prediction of its compressive failure particularly challenging.

A novel three-dimensional extension of the mesoscale modeling framework based on the mesh fragmentation technique (MFT) is proposed. Within this fully continuum approach, high-aspect-ratio interface elements (HAR-IEs) are inserted into the finite element mesh to define potential crack paths. A new two-layer condensed HAR-IE is introduced, governed by tensile and shear-frictional constitutive models, allowing the simulation of compressive failure as a combination of both mechanisms with reduced computational cost.

The proposed framework is general and can be applied to concretes containing aggregates of different origins or mechanical properties. Here, it is demonstrated through its application to RAC, for which fracture may propagate through the recycled aggregates themselves.

Numerical uniaxial compression tests were performed on mortar, natural aggregate concrete (NAC), and RAC specimens. The numerical results are in good agreement with experimental data, capturing stress–strain behavior, fracture patterns, and the influence of recycled aggregate content (0%, 50%, and 100%) on stiffness and dilatancy. The proposed approach provides a physically consistent and computationally efficient tool for studying compressive fracture in mesoscale concrete. It marks a significant advancement over previous 2D implementations by enabling the simulation of fully three-dimensional stress redistribution and failure evolution.

混凝土内部结构由集料、水泥砂浆和分布在细观水平的弱界面组成，强烈影响混凝土的准脆性力学行为。再生骨料混凝土（RAC）呈现出更加异质的细观结构，使得其压缩破坏的预测特别具有挑战性。提出了一种基于网格碎片化技术（MFT）的中尺度建模框架的三维扩展。在这种完全连续的方法中，高纵横比界面单元（HAR-IEs）被插入到有限元网格中，以定义潜在的裂纹路径。引入了一种新的两层压缩HAR-IE，由拉伸和剪切摩擦本构模型控制，允许将压缩破坏作为两种机制的组合进行模拟，同时降低了计算成本。提出的框架是通用的，可以应用于含有不同来源或机械性能的骨料的混凝土。这里，通过它在RAC中的应用证明了这一点，在RAC中，断裂可以通过再生骨料本身传播。对砂浆、天然骨料混凝土（NAC）和RAC试件进行了数值单轴压缩试验。数值结果与实验数据吻合良好，捕捉了应力-应变行为、断裂模式以及再生骨料含量（0%、50%和100%）对刚度和剪胀的影响。该方法为研究中尺度混凝土的压缩断裂提供了一种物理一致性和计算效率高的工具。它通过模拟全三维应力重分布和破坏演变，标志着比以前的2D实现有了重大进步。

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引用次数: 0

Identification of low-temperature fatigue damage states in asphalt mixtures using multivariate acoustic emission parameters 基于多元声发射参数的沥青混合料低温疲劳损伤状态识别

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2026-01-24 DOI: 10.1016/j.engfracmech.2026.111883

Hui Wei , Yunyao Liu , Jue Li , Feiyue Wang , Jianlong Zheng , Yinhan Dai

A clear understanding of the evolution, mechanisms, and stage-wise progression of low-temperature fatigue cracking in asphalt mixtures is essential for interpreting fatigue failure and improving pavement durability. This study employs acoustic emission (AE) monitoring to track the real-time fatigue-damage evolution of pre-notched asphalt mixtures subjected to four sub-zero temperatures (−5, −10, −15, and −20 °C). Stage-dependent behaviors of six AE parameters—b-value, activity S value, rise angle (RA), average frequency (AF), master frequency (MF), and average frequency centroid (AFG)—were quantified to extract precursor signatures of damage states. These multivariate features were further integrated with ensemble-learning algorithms to develop an AE-based damage-state identification framework. Results reveal consistent correspondence between AE-parameter evolution and the four damage stages (void compaction, micro-crack initiation/stable propagation, crack coalescence/unstable propagation, and complete fracture) across all temperatures. Specifically, the b-value exhibits a step-wise decline during crack coalescence, the S value maintains pronounced high-level fluctuations prior to fracture, and the coupled variations in RA, AF, MF, and AFG capture the transition in dominant damage behavior during late-stage evolution. Based on these precursor characteristics, classifiers built using AdaBoost, XGBoost, and Random Forest achieved accurate late-stage identification, with test-set accuracies of 95.4%, 94.2%, and 94.2% and corresponding AUC values of 0.956, 0.978, and 0.970. In addition, the models demonstrated strong precision–recall performance under class imbalance, achieving PR-AUC values of 0.996 (AdaBoost), 0.998 (XGBoost), and 0.998 (Random Forest). Feature-importance analysis further indicates that the S value and b-value are the most influential predictors for damage-state recognition. Overall, the proposed framework provides an interpretable and practical approach for stage-wise identification of low-temperature fatigue damage and supports the development of real-time early-warning strategies for asphalt pavements.

清楚地了解沥青混合料低温疲劳开裂的演变、机制和阶段进展，对于解释疲劳破坏和提高路面耐久性至关重要。本研究采用声发射（AE）监测来跟踪预缺口沥青混合料在四种零下温度（- 5、- 10、- 15和- 20℃）下的实时疲劳损伤演变。通过对b值、活度S值、上升角（RA）、平均频率（AF）、主频率（MF）和平均频率质心（AFG） 6个声发射参数的阶段依赖行为进行量化，提取损伤状态的前兆特征。这些多变量特征与集成学习算法进一步集成，以开发基于ae的损伤状态识别框架。结果表明，在所有温度下，ae参数的演化与四个损伤阶段（孔隙压实、微裂纹萌生/稳定扩展、裂纹合并/不稳定扩展和完全断裂）具有一致的对应关系。具体来说，b值在裂纹合并过程中呈逐步下降趋势，S值在断裂前保持明显的高水平波动，RA、AF、MF和AFG的耦合变化反映了后期演化过程中主要损伤行为的转变。基于这些前体特征，使用AdaBoost、XGBoost和Random Forest构建的分类器实现了准确的后期识别，测试集准确率分别为95.4%、94.2%和94.2%，对应的AUC值分别为0.956、0.978和0.970。此外，在类别不平衡的情况下，模型的PR-AUC值分别为0.996 （AdaBoost）、0.998 （XGBoost）和0.998 （Random Forest）。特征重要性分析进一步表明，S值和b值是对损伤状态识别影响最大的预测因子。总体而言，所提出的框架为分阶段识别低温疲劳损伤提供了一种可解释和实用的方法，并支持沥青路面实时预警策略的发展。

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引用次数: 0

Coupled infrared–mechanical signatures of crack evolution in anisotropic limestone with a hole 各向异性带孔灰岩裂纹演化的红外-力学耦合特征

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2026-01-23 DOI: 10.1016/j.engfracmech.2026.111886

Dianen Wei , Guansuo Dui , Zhenyu Sun , Yanhui Xi , Zibing Zheng

Void defects and bedding-related anisotropy govern the stability of limestone rock masses under blasting, tunneling, and mining disturbances. To elucidate the instability mechanism and thermo‑mechanical coupling of bedded limestone containing a central circular hole, we performed instrumented drop‑hammer tests while systematically varying impact velocity and bedding angle. High‑speed imaging and infrared thermography were used to quantify infrared radiation temperature (IRT), energy partitioning, and their spatiotemporal coupling with fracture evolution. Damage evolved nonlinearly through five stages—initial loading, loading plateau, main failure, secondary response, and residual vibration. With increasing impact velocity, the plastic zone expanded and limited further force growth; elastic strain‑energy storage was constrained, the hardening–softening process accelerated, and the characteristic double peak in the mechanical response collapsed toward the first peak. Crack nucleation and rapid growth occurred within a very short window early in loading: while overall displacement was still rising, local stresses reached critical levels and triggered rupture. Impact velocity and bedding angle acted jointly on the IRT response; at a bedding angle near 60°, both the temperature peak and the thermal response were greatest, indicating a critical orientation prone to heat localization and structural damage. The stress time history was tightly coupled with temperature rise: during stress accumulation, the temperature‑rise rate reflected crack initiation and frictional heating. Infrared hotspots were spatially congruent with crack trajectories but lagged in time, consistent with a “path → thermal band” evolution; stress redistribution and cooperative branching rendered the local temperature field multi‑lobed with a pronounced bedding‑parallel bias. These results provide a geology‑informed thermographic diagnostic for hole‑affected, bedded limestones and support early‑warning and design decisions in blasting, excavation, and tunneling.

裂隙缺陷和与顺层有关的各向异性控制着石灰岩岩体在爆破、掘进和开采扰动下的稳定性。为了阐明含有中心圆孔的层状石灰岩的失稳机理和热-力耦合，我们系统地改变了冲击速度和层状角度，进行了仪器落锤试验。高速成像和红外热成像技术用于量化红外辐射温度（IRT）、能量分配及其与裂缝演化的时空耦合。初始加载阶段、加载平台阶段、主破坏阶段、二次响应阶段和残余振动阶段是损伤的非线性演化阶段。随着冲击速度的增加，塑性区扩大，限制了进一步的力增长；弹性应变-能量存储受到约束，硬化-软化过程加速，力学响应特征双峰向第一个峰崩塌。在加载初期，裂纹在很短的时间窗口内迅速形核并扩展，当整体位移仍在增加时，局部应力达到临界水平并触发破裂。冲击速度和层理角共同影响IRT响应；当层理角接近60°时，温度峰值和热响应均最大，表明这是一个容易发生热局部化和结构破坏的临界取向。应力时程与温升紧密耦合，在应力积累过程中，温升速率反映了裂纹萌生和摩擦升温。红外热点在空间上与裂纹轨迹一致，但在时间上滞后，符合“路径→热带”的演化规律；应力重分布和协同分支使局部温度场呈多分叶状，具有明显的层理平行偏倚。这些结果为受孔影响的层状灰岩提供了地质信息的热成像诊断，并为爆破、开挖和隧道的早期预警和设计决策提供了支持。

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引用次数: 0

Micro-mechanisms of ductile fracture in Q550 high-strength structural steel using X-ray μCT integrated with digital volume correlation (DVC) 基于数字体积相关（DVC）的x射线μCT分析Q550高强结构钢韧性断裂微观机制

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2026-01-23 DOI: 10.1016/j.engfracmech.2026.111884

Bo-chuan Jiang , Xin-yang Gao , Zhao-xia Qu , Liang-jiu Jia

Understanding ductile fracture behaviors of high-strength structural steel is essential for safe and efficient design of modern infrastructures. This study focused on fracture mechanisms and internal void evolution during ductile fracture of Q550 high-strength structural steel using in-situ X-ray computed tomography (CT) integrated with digital volume correlation (DVC) techniques. The results demonstrate that fracture is governed by void nucleation, growth, and coalescence, driven by significant strain localization around big voids after necking. A progressive increase in porosity from 0.006‰ to 0.96‰ within the region of interest (ROI), with over 95% of voids nucleating in the post-necking stage. The evolution of voids is strongly dependent on local plastic strain. Voids within the strain-concentrated necking region undergo significant volumetric growth and morphological change, while those outside remain nearly spherical. Incremental DVC analyses quantify this strain localization and reveal concurrent damage accumulation within the necking center and elastic unloading in surrounding regions in the post-necking stage. In the final stage before fracture, local strain in the necking center exceeds 25%, far above the global average of 14.7%. The resulting high stress triaxiality promotes multi-directional void growth (in the X-, Y-, and Z-axis directions) and facilitates coalescence, initiating transverse micro-cracks that progressively reduce the load-bearing cross-section. Fractographic analysis of the cup-and-cone morphology confirms a void-mediated mechanism, with dimples in the central fibrous zone providing direct evidence of coalescence preceding final failure. This work elucidates the intrinsic link between macroscopic strain localization, microscopic void evolution, and the ultimate ductile fracture in high-strength steel.

了解高强结构钢的韧性断裂行为对现代基础设施的安全高效设计至关重要。采用原位x射线计算机断层扫描（CT）和数字体积相关（DVC）技术对Q550高强度结构钢韧性断裂的断裂机制和内部空洞演化进行了研究。结果表明，裂纹断裂主要受孔洞形核、生长和聚并控制，主要受颈缩后大孔洞周围的应变局部化驱动。在感兴趣区域内，孔隙度由0.006‰逐渐增加到0.96‰，95%以上的孔隙在后颈缩阶段成核。孔洞的演化与局部塑性应变密切相关。在应变集中的颈缩区域内的空洞发生了显著的体积增长和形态变化，而外部的空洞则保持近球形。增量DVC分析量化了这种应变局部化，揭示了后颈化阶段颈化中心的损伤累积和周边区域的弹性卸载。断裂前最后阶段，颈化中心局部应变超过25%，远高于全球平均水平14.7%。由此产生的高应力三轴性促进了多向空隙生长（在X、Y和z轴方向），并促进了聚并，形成横向微裂纹，逐渐减小了承载截面。对杯状和锥状形貌的断口分析证实了空洞介导的机制，中心纤维带的凹窝提供了最终破裂之前合并的直接证据。本研究阐明了高强钢宏观应变局部化、微观空洞演化与最终韧性断裂之间的内在联系。

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引用次数: 0

Analytical solutions for the initial and periodic fracture of hard roof in longwall mining considering progressive deterioration of coal seam stiffness 考虑煤层刚度逐渐退化的长壁开采硬顶板初始断裂和周期性断裂解析解

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2026-01-23 DOI: 10.1016/j.engfracmech.2026.111876

Peinan Wu , Qiang Zhang , Kai Huang , YueJin Zhou , HaiXu Xu , Kai Wang

The mechanical response of the roof and coal seam is important to the stability control in coal mining engineering. Given the nonlinear evolution of overburden pressure and the variation in coal seam stiffness caused by mining, the roof-coal seam was discretized into a series of smaller segments, characterized by linear roof pressure and constant foundation stiffness. The analytical solutions for the mechanical response of each segment were derived using the governing equations for the initial and periodically fractured roof. Using an iterative numerical algorithm, integral coefficients and exact foundation stiffness values were determined based on the evolution of progressive degradation in coal seam stiffness. The theoretical results show good agreement with existing numerical and analytical solutions. The degradation of coal seam stiffness leads to a non-monotonic evolution of bearing pressure, initially increasing, followed by a decrease, which aligns closely with field-monitored data. The sensitivity analysis further revealed that overburden pressure, roof thickness, and coal seam thickness exert a significant influence on deflection and internal forces of the roof. The proposed solution offers theoretical guidance for safety evaluation and hydraulic support design in longwall mining.

在煤矿工程中，顶板和煤层的力学响应是稳定控制的重要内容。考虑到覆岩压力的非线性演化和开采引起的煤层刚度变化，将顶板-煤层离散为一系列较小的分段，顶板压力为线性，基础刚度为恒定。利用初始破断和周期性破断顶板的控制方程，推导出各段的力学响应解析解。基于煤层刚度逐渐退化的演化过程，采用迭代数值算法确定了积分系数和精确的基础刚度值。理论结果与已有的数值解和解析解吻合较好。煤层刚度退化导致承压压力呈先升高后降低的非单调演化规律，与现场监测数据基本一致。敏感性分析进一步表明，覆岩压力、顶板厚度、煤层厚度对顶板挠度和内力有显著影响。为长壁开采的安全评价和液压支架设计提供了理论指导。

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引用次数: 0

Experiment and analysis on cumulative damage and fragmentation of granite under cyclic impact 循环冲击作用下花岗岩累积损伤破碎试验与分析

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2026-01-22 DOI: 10.1016/j.engfracmech.2026.111878

Jianxiu Wang , Ansheng Cao , Yuanbo Gao , Luyu Lin , Hua Zhang , Pengfei Liu

The dynamic characteristics of rock under cyclic impact loading exhibited nonlinear behavior and high strain rate effects. To investigate the response of granite under medium strain rate impact, cyclic impact tests were conducted for 100 × 100 × 100 mm cubic specimens using a drop hammer impact machine at varying heights. The stress–strain, macroscopic fragmentation, and energy dissipation characteristics were analyzed under cyclic impact. High-speed cameras and Digital Image Correlation (DIC) technology were employed to record and analyze the strain evolution and crack propagation on the specimen surfaces. Ultrasonic testing was used to measure the wave velocity of the specimens. The cumulative damage characteristics of the granite under cyclic impact were assessed. The fragmented rock pieces were sieved, and the fractal dimensions of the fragmentation were analyzed to characterize the failure patterns. The mesoscopic cracks of the fragments after impact were analyzed by SEM. The stress-time curve of the specimen comprised four stages: rising stage, plateau stage, secondary rising stage, and unloading stage. The stress–strain curve was divided into compaction stage, linear elastic stage, elastoplastic stage and failure stage. With the increasing cyclic impact number, the peak stress decreased, energy efficiency increased, and damage accumulated. Concurrently, the strain concentration area gradually increased and showed an obvious localization phenomenon. As the impact height increased, the crack propagation rate accelerated, its resistance to deformation diminished, and the number of internal fracture planes increased, leading to a high fractal dimension of the rock fragmentation. With the increase of impact height, the specimens sequentially exhibited splitting failure, block failure, and pulverization. Meanwhile, the mesoscopic fracture of granite changed from being dominated by intergranular fracture to being dominated by transgranular fracture. The research results provide theoretical support and reference for stability assessments of rock engineering under impact loading.

岩石在循环冲击载荷作用下的动力特性表现出非线性和高应变率效应。为研究花岗岩在中应变率冲击下的响应，采用落锤冲击试验机对100 × 100 × 100 mm立方试样进行了不同高度的循环冲击试验。分析了循环冲击作用下的应力-应变、宏观破碎和能量耗散特性。采用高速摄像机和数字图像相关（DIC）技术记录和分析试样表面的应变演化和裂纹扩展。采用超声检测方法测量试样的波速。评估了花岗岩在循环冲击作用下的累积损伤特征。对破碎的岩块进行筛分，分析破碎的分形维数来表征破碎的破坏模式。利用扫描电镜对冲击后碎片的细观裂纹进行了分析。试件的应力-时间曲线分为上升阶段、平台阶段、二次上升阶段和卸载阶段。应力-应变曲线分为压实阶段、线弹性阶段、弹塑性阶段和破坏阶段。随着循环冲击次数的增加，峰值应力减小，能量效率提高，损伤逐渐累积。同时，应变集中面积逐渐增大，呈现明显的局部化现象。随着冲击高度的增加，裂纹扩展速度加快，抗变形能力减弱，内部断裂面数量增加，导致岩石破碎的分形维数较高。随着冲击高度的增加，试样依次表现为劈裂破坏、块体破坏和粉化。同时，花岗岩的细观断裂由以沿晶断裂为主转变为以穿晶断裂为主。研究结果为冲击荷载作用下岩石工程的稳定性评价提供了理论支持和参考。

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引用次数: 0

Analysis of damage and fracture mechanisms in quartzite with different inclination angles under liquid oxygen phase change-induced fracturing 不同倾角石英岩液氧相变压裂损伤及破裂机理分析

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2026-01-22 DOI: 10.1016/j.engfracmech.2026.111880

Yan-bing Wang , Dai-rui Fu , Xiao-yan Zhao , Xiao-guang Zhou , Qing-wen Li , Xiao Wang , Tie-jun Tao

To address the unresolved damage mechanisms and unclear fracture propagation laws of jointed rock masses subjected to gas-expansion-induced rock breaking, a series of liquid-oxygen phase-transition fracturing model tests combined with X-ray CT–based three-dimensional reconstruction were conducted. The damage evolution characteristics of rock masses with different structural configurations under high-pressure gas loading were systematically investigated, and the dynamic propagation behavior and three-dimensional spatial distribution of blast-induced fractures were revealed. The results indicate that the joint inclination angle reconstructs the energy distribution pattern by regulating the reflection–refraction behavior of stress waves. With increasing joint inclination, the strain response exhibits alternating tensile–compressive characteristics, manifested by enhanced tensile strain peaks and attenuated compressive strain peaks, which in turn drive the systematic evolution of fracture geometric parameters: the average fracture width increases monotonically, the average fracture orientation angle continuously decreases, while the surface density and crushed-zone area show pronounced nonlinear variations. Fracture network parameters respond in a differentiated manner: the fracture surface area, fracture volume, and fracture ratio reach peak values at specific inclination angles, whereas fracture length, width, and equivalent diameter increase monotonically. Furthermore, a coupled damage–porosity heterogeneity characterization index is proposed, quantitatively revealing the nonlinear decay laws of the volumetric fractal dimension and damage degree under the gradient control of joint inclination. This index effectively characterizes the coupling mechanism between damage propagation and pore structure evolution in jointed rock masses subjected to gas-driven fracturing.

针对节理岩体气胀破岩损伤机制不明确、裂缝扩展规律不明确等问题，开展了一系列液氧相变压裂模型试验，并结合x射线ct三维重建。系统研究了高压气体荷载作用下不同结构形态岩体的损伤演化特征，揭示了爆破裂隙的动态扩展行为和三维空间分布。结果表明，节理倾角通过调节应力波的反射-折射行为，重构了应力波的能量分布模式。随着节理倾角的增大，应变响应呈现拉压交变特征，表现为拉应变峰值的增强和压应变峰值的减弱，从而驱动裂缝几何参数的系统演化：平均裂缝宽度单调增加，平均裂缝取向角不断减小，表面密度和破碎区面积呈现明显的非线性变化。裂缝网络参数的响应具有差异性：裂缝表面积、裂缝体积和裂缝比在特定倾角处达到峰值，而裂缝长度、裂缝宽度和等效直径单调增加。在此基础上，提出了损伤-孔隙非均质耦合表征指标，定量揭示了节理倾角梯度控制下体积分形维数和损伤程度的非线性衰减规律。该指标有效表征了气致压裂节理岩体损伤扩展与孔隙结构演化的耦合机制。

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引用次数: 0

Frequency-based approach for fatigue life analysis of SLM high-strength aluminum alloys 基于频率的SLM高强铝合金疲劳寿命分析方法

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2026-01-21 DOI: 10.1016/j.engfracmech.2026.111866

Yuqi Yang, Haibiao Yin, Weixing Yao, Zuoting Liu

High-strength aluminum alloys manufactured by Selective Laser Melting (SLM) technology are widely used in high-performance aerospace components due to their combination of high strength, low density, and excellent corrosion resistance. This study investigates the high-cycle fatigue (HCF) behavior of SLM-manufactured TiB2-Al (FCA101Y-1) and AlMgScZr high-strength aluminum alloys under vibrational loading. A frequency-based approach is proposed for fatigue life prediction given the strong correlation between natural frequency variation and damage accumulation. The approach accounts for the influence of fracture surface defects, characterized and analyzed through Scanning Electron Microscopy (SEM) and Optical Microscopy (OM). Model calculation results indicate that crack growth and brittle fracture stages account for approximately 80% and 20% of the total fatigue life of SLM aluminum alloys, respectively. This approach has proven reliable, as the predicted fatigue lives fall within a factor-of-two scatter band and coefficient of determination

R^{2}

is all around 0.9.

采用选择性激光熔化（SLM）技术制造的高强度铝合金具有高强度、低密度和优异的耐腐蚀性，广泛应用于高性能航空航天部件中。研究了slm制造的TiB2-Al （FCA101Y-1）和AlMgScZr高强度铝合金在振动载荷下的高周疲劳行为。考虑到固有频率变化与损伤累积之间的强相关性，提出了一种基于频率的疲劳寿命预测方法。该方法考虑了断口表面缺陷的影响，并通过扫描电镜（SEM）和光学显微镜（OM）对其进行了表征和分析。模型计算结果表明，裂纹扩展阶段和脆性断裂阶段分别约占SLM铝合金总疲劳寿命的80%和20%。该方法已被证明是可靠的，因为预测的疲劳寿命落在2因子散射带内，决定系数R2都在0.9左右。

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引用次数: 0

Comprehensive mechanical evaluation of heat-treated AISI 4140 (ETD 150): fatigue behavior and novel indentation-based characterization of fracture toughness and hardness with relevance to rail steels 热处理AISI 4140 （etd150）的综合力学评价：疲劳行为和与轨道钢相关的基于压痕的断裂韧性和硬度的新表征

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2026-01-20 DOI: 10.1016/j.engfracmech.2026.111874

S.I. Okocha , M.T. Hendry , P.Y.B. Jar

This study investigates the fracture toughness (K_JC) and hardness of heat-treated, cold-drawn AISI 4140 alloy (“e.t.d” 150) alongside three representative rail steels (JP, EV, and CZ) to comparatively evaluate their mechanical performance. Importance is placed on “e.t.d” 150 to assess its potentiality as a viable alternative material for rail steel applications based on current insights to rail steel material recycling and substitution. Fracture toughness (K_JC) was assessed using a chamfered cylindrical flat-end and spherical indenter based on a novel virtual J-integral approach that minimizes the plastic J-integral component based on Irwin’s elastic solution, while hardness was obtained using only spherical indentation. A comparison between the K_JC outcomes of both indenters are presented and discussed, showing preference to spherical indentation. The virtual J-integral approach with limit load analysis applied for estimating K_JC in both indenters, incorporated stress triaxiality to account for pressure sensitivity and the hydrostatic pressure component in indentation testing. Results show that “e.t.d” 150 achieves fracture toughness and Brinell hardness values comparable to rail steels, particularly suitable for curved track sections where wear resistance and durability are critical. Fatigue analysis was also conducted for “e.t.d” 150, which confirms moderate-to-good resistance to rolling contact fatigue. These findings suggest that “e.t.d” 150 offers a reliable alternative for substituting conventional rail steels, with potential benefits for railway performance, safety, and maintenance cost reduction.

本文研究了热处理冷拔AISI 4140合金的断裂韧性（KJC）和硬度。d“150”)与三种具有代表性的钢轨钢（JP， EV和CZ）比较，比较其机械性能。“e.t.”很重要。D ' 150，根据目前对轨道钢材料回收和替代的见解，评估其作为轨道钢应用的可行替代材料的潜力。断裂韧性（KJC）是使用倒角圆柱平端和球面压头进行评估的，该方法基于一种新颖的虚拟j积分方法，该方法基于Irwin弹性解最小化了塑性j积分分量，而硬度仅使用球面压头获得。两种压痕的KJC结果之间的比较提出和讨论，显示偏爱球形压痕。虚拟j积分方法和极限载荷分析应用于估计压痕的KJC，结合应力三轴性来考虑压痕测试中的压力敏感性和静水压力分量。结果表明：“e.t.。d ' 150具有与钢轨钢相当的断裂韧性和布氏硬度值，特别适用于对耐磨性和耐久性至关重要的弯曲轨道部分。对“e.t.”进行了疲劳分析。D ' 150，具有中等到良好的抗滚动接触疲劳性能。这些发现表明，《e.t.外星人》D”150提供了替代传统钢轨的可靠选择，具有提高铁路性能、安全性和降低维护成本的潜在优势。

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引用次数: 0

A dislocation density-based crystal plasticity finite element analysis of cyclic softening behavior of AISI H13 steel under isothermal fatigue AISI H13钢等温疲劳循环软化行为的位错密度晶体塑性有限元分析

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2026-01-20 DOI: 10.1016/j.engfracmech.2026.111870

Boya Wu , Meichen Liu , Shangyi Dai , Junwan Li , Xiaochun Wu

This study reveals the cyclic softening mechanisms of AISI H13 steel under isothermal fatigue at 600°C through experimental characterization and dislocation density-based crystal plasticity finite element method. Experiments demonstrate that AISI H13 steel exhibits three distinct softening stages within the strain amplitude range of 0.5–1.1%, namely rapid softening, transitional softening, and steady softening. Microstructural analysis reveals that with increasing cycles, the softening phenomenon intensifies, with dislocation density continuously decreasing from rapid to slow rates, accompanied by the coarsening of carbides. Accordingly, a dislocation density-based crystal plasticity model coupling realistic martensitic lath block structures and damage evolution was developed to reveal cyclic softening mechanisms, achieving hysteresis loop predictions with errors below 5%. The model reveals the dominant role of statistically stored dislocations (SSD) in cyclic softening, with SSD density decreasing from 1.68 × 10³ to 1.53 × 10³ μm⁻² within the first five cycles. This non-uniform recovery process generates stress concentration in high SSD regions and strain localization in low SSD regions, leading to strong coupling between damage and plastic strain that drives progressive steel degradation. Simulation results further demonstrate that increasing strain amplitude from 0.5% to 1.1% significantly enhances strain localization, with accumulated plastic strain in localized regions reaching 0.5 at the 5th cycle under high amplitude compared to merely 0.002 under low amplitude. This heterogeneity accelerates damage evolution, with damage variables exceeding 0.15 in critical regions at 1.1% strain amplitude while remaining zero at 0.5%, ultimately reducing fatigue life from 650 to 214 cycles and promoting secondary crack formation near primary crack tips.

本研究通过实验表征和基于位错密度的晶体塑性有限元法揭示了AISI H13钢在600℃等温疲劳下的循环软化机理。试验表明，AISI H13钢在0.5 ~ 1.1%应变幅值范围内呈现出快速软化、过渡软化和稳定软化三个阶段。显微组织分析表明，随着循环次数的增加，软化现象加剧，位错密度由快变慢不断降低，碳化物逐渐变粗。因此，建立了一个基于位错密度的晶体塑性模型，该模型结合了真实马氏体板条块结构和损伤演化，揭示了循环软化机制，实现了误差低于5%的滞后回路预测。该模型揭示了统计存储位错（SSD）在循环软化中的主导作用，在前5次循环中，SSD密度从1.68 × 103 μm−2下降到1.53 × 103 μm−2。这种不均匀的恢复过程在高SSD区域产生应力集中，在低SSD区域产生应变局部化，导致损伤和塑性应变之间的强耦合，从而驱动钢的渐进退化。仿真结果进一步表明，应变幅值从0.5%增加到1.1%显著增强了应变局部化，高幅值下第5次循环局部化区域累积塑性应变达到0.5，而低幅值下仅为0.002。这种非均质性加速了损伤演化，当应变幅值为1.1%时，损伤变量在临界区域超过0.15，而当应变幅值为0.5%时，损伤变量为零，最终将疲劳寿命从650次循环降低到214次循环，并促进主裂纹尖端附近的二次裂纹形成。

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