Engineering Fracture Mechanics最新文献_第7页

Application of the Weibull distribution to assess fracture resistance of rubberized epoxy asphalt mixture with SCB specimens 用威布尔分布评价橡胶环氧沥青混合料SCB试件的抗断裂性能

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-12-11 DOI: 10.1016/j.engfracmech.2025.111798

Chenguang Shi , Tianling Wang , Xing Cui , Peng Guo , Hongzhou Zhu , Junfeng Gao , Jun Yang

This study employs the probability density function of the Weibull distribution to model the fracture energy damage density derived from force–displacement curves in semi-circular bending (SCB) tests of epoxy asphalt mixtures containing crumb rubber (CR). Key Weibull parameters—β and η—along with derived indices (IBS, CBS, Entropy, and Weibull_CRI), were analyzed to evaluate crack resistance across varying CR contents, temperatures, and loading rates. The results indicate that increased CR content enhances ductility and fracture energy but reduces stiffness, while higher temperatures promote viscoelasticity and decrease failure load. The shape parameter β reflects failure mechanisms, with higher values indicating brittleness. Whereas, the scale parameter η correlates with damage propagation and toughness. A critical transition in mechanical behavior occurs at 4 % CR, characterized by a shift from an aggregate-dominated to a rubber-dominated response. Compared to conventional indicators, the Weibull-based fracture indices are more sensitive to variations in material composition and loading conditions. Correlation analysis shows that η and Weibull_CRI exhibit strong positive correlations (r > 0.94) with toughness indices (TI, CRI, CRI^pre), confirming their reliability as indicators of crack resistance. In contrast, β and IBS correlate strongly with stiffness-related parameters but negatively with flexibility metrics. Entropy moderately relates to toughness variability, while CBS shows weak predictive utility. This study establishes η and Weibull_CRI as robust indicators for evaluating fracture performance, providing a quantitative framework for optimizing rubber-modified asphalt mixtures under diverse service conditions.

本文采用威布尔分布的概率密度函数，对含橡胶颗粒环氧沥青混合料半圆弯曲（SCB）试验中由力-位移曲线得出的断裂能损伤密度进行建模。关键Weibull参数-β和η -以及衍生指数（IBS， CBS， Entropy和WeibullCRI）进行分析，以评估不同CR含量，温度和加载速率下的抗裂性。结果表明：CR含量的增加提高了材料的延性和断裂能，但降低了材料的刚度，而温度的升高提高了材料的粘弹性，降低了材料的破坏载荷。形状参数β反映了破坏机制，值越大表示脆性。而尺度参数η与损伤扩展和韧性有关。力学行为的关键转变发生在4% CR时，其特征是从以聚集体为主的反应转变为以橡胶为主的反应。与常规断裂指标相比，基于weibull的断裂指标对材料成分和加载条件的变化更为敏感。相关分析表明，η和WeibullCRI与韧性指标（TI、CRI、CRIpre）呈强正相关（r > 0.94），证实了它们作为抗裂指标的可靠性。相反，β和IBS与刚度相关参数密切相关，但与灵活性指标负相关。熵适度地与韧性变异性相关，而CBS表现出较弱的预测效用。该研究建立了η和WeibullCRI作为评估断裂性能的稳健指标，为在不同使用条件下优化橡胶改性沥青混合料提供了定量框架。

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引用次数: 0

Overcoming thermal weakening history in granite: synergistic application of ultrasonic fatigue and residual heat 克服花岗岩的热弱化历史：超声疲劳和余热的协同应用

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-12-11 DOI: 10.1016/j.engfracmech.2025.111797

Huaiguang Xiao , Yubo Li , Lei He , Chuanzi Du , Yueyang Li , Tienan Wang

Efficient and low-energy fragmentation of deep, hot, hard rock is a critical technological bottleneck for accessing future geothermal and deep mineral resources. This study first identifies and characterizes a thermal weakening history in granite subjected to cyclic microwave irradiation, a phenomenon where damage accumulation saturates and subsequent thermal shocks yield diminishing returns. This research introduces and validates a novel synergistic strategy that leverages the residual heat from microwave pre-treatment to sensitize the hot rock to subsequent fatigue damage from low-power ultrasonic vibration. Granite specimens underwent a two-stage process that brief microwave pre-heating followed immediately by a short duration of ultrasonic vibration on the still-hot rock. These findings indicate a thermal sensitization fatigue effect arising from the interplay of thermal stress and ultrasonic vibration. Microwave pre-treatment, by inducing thermal-cracks and reducing the fracture toughness, eliminates the long fatigue accumulation stage typical of ultrasonic treatment alone. Critically, the damage efficiency was enhanced by over an order of magnitude in pre-heated rock compared to unheated rock, confirming that residual heat transforms the slow fatigue process into a highly effective damage mechanism. This research offers a novel technical pathway for rock-breaking challenges in deep engineering by establishing high-frequency fatigue fracturing of thermally-stressed hard rocks.

高效、低能量破碎深、热、硬岩石是获取未来地热和深部矿产资源的关键技术瓶颈。本研究首先确定并描述了周期性微波照射下花岗岩的热弱化历史，即损伤积累饱和，随后的热冲击产生递减收益的现象。本研究引入并验证了一种新的协同策略，即利用微波预处理的余热使热岩对低功率超声振动的后续疲劳损伤敏感。花岗岩试样经历了两个阶段的过程，即短暂的微波预热，随后在仍热的岩石上立即进行短时间的超声波振动。这些结果表明，热应力和超声振动的相互作用产生了热致敏疲劳效应。微波预处理通过诱导热裂纹和降低断裂韧性，消除了单纯超声处理所特有的长时间疲劳积累阶段。重要的是，与未加热岩石相比，预热岩石的损伤效率提高了一个数量级以上，这证实了余热将缓慢的疲劳过程转化为一种高效的损伤机制。本研究通过建立热应力硬岩的高频疲劳断裂，为深部工程破岩挑战提供了新的技术途径。

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引用次数: 0

A thermodynamics-based damage-coupled non-unified viscoplastic constitutive model: formulation, finite element implementation, and validation 基于热力学的损伤耦合非统一粘塑性本构模型：公式、有限元实现和验证

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-12-11 DOI: 10.1016/j.engfracmech.2025.111786

Yang Shu , Kang-Kang Wang , Fan Wu , Jian-Feng Wen , Shan-Tung Tu

Creep deformation, damage evolution, and crack growth collectively govern the structural integrity and long-term safety of engineering components operating in high temperature environments. Existing non-unified viscoplastic models typically introduce damage variables only into the creep law while neglecting their effects on elastic–plastic constitutive relations. To address this limitation, we establish a thermodynamically consistent, damage-coupled non-unified viscoplastic model grounded in the effective stress concept. By incorporating the effective stress tensor, the model couples the damage variable with the elastic, plastic, and creep strain tensors, comprehensively characterizing damage evolution effects on macroscopic mechanical behavior. The model was implemented through a user-defined material subroutine and validated against experimental creep crack growth data for 316H (550 ℃) and 316 (600 ℃) stainless steels, showing excellent predictive accuracy. Furthermore, the influence of loading methods, mesh size, and key parameters (maximum time increment size, coefficient of friction, and material parameter α) was discussed. Results show that proper loading conditions and parameter selection significantly improve simulation efficiency and accuracy. This work provides a critical reference framework for the accurate prediction of creep damage and creep crack growth in high temperature structures.

蠕变变形、损伤演化和裂纹扩展共同决定了高温环境下工程构件的结构完整性和长期安全性。现有的非统一粘塑性模型通常只在蠕变规律中引入损伤变量，而忽略了损伤变量对弹塑性本构关系的影响。为了解决这一限制，我们建立了一个基于有效应力概念的热力学一致，损伤耦合的非统一粘塑性模型。该模型通过引入有效应力张量，将损伤变量与弹性、塑性和蠕变应变张量耦合，全面表征损伤演化对宏观力学行为的影响。该模型通过用户定义的材料子程序实现，并与316H（550℃）和316（600℃）不锈钢的蠕变裂纹扩展实验数据进行了验证，显示出良好的预测精度。此外，还讨论了加载方式、网目尺寸和关键参数（最大时间增量尺寸、摩擦系数和材料参数α）的影响。结果表明，适当的加载条件和参数选择可显著提高仿真效率和精度。该工作为准确预测高温结构的蠕变损伤和蠕变裂纹扩展提供了重要的参考框架。

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引用次数: 0

Numerical study on the crack evolution and energy conversion characteristics of the strain burst experiment under different intermediate principal stresses 不同中间主应力下应变破裂实验裂纹演化及能量转换特性的数值研究

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-12-10 DOI: 10.1016/j.engfracmech.2025.111796

Hao Qi , Xueyang Xing , Dejian Li , Lu Chen , Shuai Du , Hao Zhang

To investigate the effects of the intermediate principal stress(σ_2d) on strain burst characteristics, a series of experiments were conducted on granite specimens. A three-dimensional continuous-discontinuous numerical model, incorporating mineral heterogeneity and micro structure mechanical properties, was established using Abaqus, cohesive zone model and secondary development to simulate strain burst experiments. The dynamic failure phenomena, stress and strain states, micro to macro crack evolution processes and energy conversion characteristics of the strain burst were investigated. Results show that the dynamic failure phenomena, macroscopic fracture patterns and stress states of the model results agree well with the experimental observations. As σ_2d increases: (1) The average velocity of ejected elements and burst pit volume decreases to a minimum at σ_2d = 0.4σ_c, indicating the weakest strain burst intensity. (2) The vertical stress peak and volume strain peak tend to increase. Early warning of strain burst, based on volume strain and crack evolution behavior, becomes most difficult at σ_2d = 0.4σ_c. (3) Cohesive elements primarily undergo tension-shear and compression-shear fracture behavior. The spatial inhomogeneity and discreteness of compression-shear damaged cohesive increase to the strongest at σ_2d = 0.4σ_c, and the macroscopic fracture pattern gradually shifts from tension-shear to shear destruction. (4) The proportion of friction energy peaks at σ_2d = 0.4σ_c, while the proportions of damage energy and kinetic energy reach their lowest. This study reveals the influence mechanism of σ_2d on the intensity of strain burst, spatial–temporal evolution behavior of macro and micro cracks, and energy conversion characteristics. The micro crack damage mechanism and energy mechanism during the strain burst are explained clearly, and two relatively novel indicators for strain burst early warning are proposed.

为研究中间主应力（σ2d）对花岗岩试样应变破裂特性的影响，进行了一系列试验研究。利用Abaqus、黏聚带模型和二次开发技术，建立了考虑矿物非均质性和细观结构力学性能的三维连续-不连续数值模型，模拟应变冲击试验。研究了应变破裂的动态破坏现象、应力应变状态、微观到宏观裂纹演化过程和能量转换特征。结果表明，模型的动态破坏现象、宏观断裂模式和应力状态与实验结果吻合较好。随着σ2d的增大：(1)在σ2d = 0.4σc时，弹射件的平均速度和爆裂坑体积减小到最小，表明应变爆裂强度最弱。(2)竖向应力峰值和体积应变峰值有增大的趋势。在σ2d = 0.4σc时，基于体积应变和裂纹演化行为的应变破裂预警最为困难。(3)黏性构件主要经历拉剪和压剪断裂。压剪破坏黏结的空间不均匀性和离散性在σ2d = 0.4σc时达到最强，宏观断裂模式逐渐由拉剪破坏向剪切破坏转变。(4)摩擦能占比在σ2d = 0.4σc处达到峰值，损伤能和动能占比最低。研究揭示了σ2d对应变破裂强度、宏微观裂纹时空演化行为及能量转换特性的影响机理。阐明了应变破裂过程中微裂纹的损伤机制和能量机制，提出了两个较为新颖的应变破裂预警指标。

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引用次数: 0

Predicting fracture toughness of hydrogen-exposed Zr-2.5Nb using physics-informed neural network 利用物理信息神经网络预测氢暴露Zr-2.5Nb的断裂韧性

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-12-08 DOI: 10.1016/j.engfracmech.2025.111782

Rohan Kushwaha, Ankur Chauhan

A physics-informed neural network (PINN) framework is developed to predict the fracture toughness of hydrogen-exposed Zr-2.5Nb by integrating domain knowledge with data-driven learning. The model incorporates the established trend of temperature-dependent toughness degradation due to hydrogen ingress and hydride formation through a physics-based regularization term, ensuring consistency with underlying embrittlement mechanisms. Using six physically meaningful input features — test temperature, hydrogen content, radial hydride fraction, yield stress, Poisson’s ratio, and elastic modulus — the PINN learns the key multivariate interactions that control fracture resistance of Zr-2.5Nb. When benchmarked against five widely used machine learning models, the PINN delivers the highest accuracy, achieving an average R

^{2}

of about 85 percent, the lowest mean-squared error, and strong generalization to unseen datasets, with most predictions falling within a

\pm

0.2 error band. SHapley Additive exPlanations (SHAP) analysis identifies test temperature, radial hydride fraction, and hydrogen content as the dominant factors influencing toughness, reinforcing the physical soundness of the model. The framework captures temperature-dependent toughness across a wide range of hydrogen concentrations and morphology-based hydride fraction, including conditions not explored experimentally. Collectively, these capabilities provide a fast and cost-effective method for estimating fracture toughness while maintaining physical interpretability, and the framework’s adaptable structure makes it suitable for extension to other materials and property-prediction tasks.

通过将领域知识与数据驱动学习相结合，开发了一种基于物理信息的神经网络（PINN）框架，用于预测氢暴露Zr-2.5Nb的断裂韧性。该模型通过基于物理的正则化项纳入了由氢气进入和氢化物形成引起的温度相关韧性退化趋势，确保了与潜在脆化机制的一致性。通过六个物理上有意义的输入特征——测试温度、氢含量、径向氢化物分数、屈服应力、泊松比和弹性模量——PINN学习了控制Zr-2.5Nb抗断裂能力的关键多元相互作用。当与五种广泛使用的机器学习模型进行基准测试时，PINN提供了最高的准确性，实现了约85%的平均R2，最低的均方误差，以及对未见过的数据集的强大泛化，大多数预测落在±0.2的误差范围内。SHapley加性解释（SHAP）分析确定了测试温度、径向氢化物分数和氢含量是影响韧性的主要因素，增强了模型的物理稳健性。该框架捕获了在广泛的氢浓度和基于形态的氢化物分数范围内的温度依赖韧性，包括实验未探索的条件。总的来说，这些功能提供了一种快速且经济有效的方法来估计断裂韧性，同时保持物理可解释性，并且框架的适应性结构使其适合扩展到其他材料和性能预测任务。

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引用次数: 0

Influence of the hard-to-soft rock layer thickness ratio on the tensile strength of Brazilian disc specimens and the stability of anti-dip slopes 软硬岩层厚度比对巴西盘试件抗拉强度及抗倾边坡稳定性的影响

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-12-08 DOI: 10.1016/j.engfracmech.2025.111772

Xiangliang Xing , Penghai Deng , Quansheng Liu , Haoran Xu

Soft-hard interbedded anti-dip slopes (SHIADSs) are frequently encountered in slope engineering. Previous studies have rarely considered the influence of the thickness ratio between hard and soft rock layers on the tensile strength of soft-hard interbedded rock specimens and the stability of SHIADSs. Therefore, the finite-discrete element method (FDEM) was adopted to study the influence of the layer thickness ratio on the strength characteristics and failure behavior of soft-hard interbedded rock specimens, as well as its influence on slope stability and failure modes. The research results show that: (1) When using FDEM to study layered rock masses, unstructured mesh topology should be employed, and the number of mesh layers in a single rock layer should not be less than 3 layers; (2) As the layer thickness ratio δ increases, the tensile strength of the specimens increases in a power function. However, depending on the layer thickness ratio δ, the relationship between tensile strength and layer dip angle θ can be divided into three modes: V-shaped variation when δ ≤ 1.0, irrelevance to layer dip angle when δ = 2.0, and a gradual decrease with the increase of layer dip angle when δ ≥ 3.0; (3) The safety factor of SHIADSs increases in a power function with the increase of the layer thickness ratio, which is similar to the variation law of tensile strength. In addition, for slopes with the same layer thickness ratio, their safety factors first decrease and then increase with the increase of the layer dip angle, reaching the minimum value when the layer dip angle is 60°-70°; (4) According to the differences in layer dip angles and layer thickness ratios of SHIADSs, the failure mechanisms can be divided into 7 types, and the failure mode can be classified into 3 types: sliding failure, toppling-sliding failure, and toppling failure. This fills the gap in previous studies where only the toppling failure mode was considered.

软-硬互层抗倾边坡是边坡工程中经常遇到的问题。以往的研究很少考虑软硬岩层厚度比对软硬互层岩石试件抗拉强度和shiads稳定性的影响。因此，采用有限离散单元法（FDEM）研究层厚比对软硬互层岩石试件强度特征和破坏行为的影响，以及对边坡稳定性和破坏模式的影响。研究结果表明：(1)利用FDEM对层状岩体进行研究时，应采用非结构化网格拓扑，且单个岩层的网格层数不小于3层；(2)随着层厚比δ的增大，试件的抗拉强度呈幂函数增长。而根据层厚比δ的不同，抗拉强度与层倾角θ的关系可分为三种模式：δ≤1.0时呈v型变化，δ = 2.0时与层倾角无关，δ≥3.0时随层倾角的增大而逐渐减小；(3) SHIADSs的安全系数随层厚比的增加呈幂函数增长，与抗拉强度的变化规律相似。此外，对于相同层厚比的边坡，其安全系数随层倾角的增大先减小后增大，在层倾角为60°~ 70°时达到最小值；(4)根据SHIADSs层倾角和层厚比的差异，将其破坏机制划分为7种类型，破坏模式可分为滑动破坏、倾倒-滑动破坏和倾倒破坏3种类型。这填补了以往研究中只考虑倾倒破坏模式的空白。

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引用次数: 0

Analysis of lateral stress and temperature effects in the true triaxial compression-shear process of granite 花岗岩真三轴压剪过程中侧向应力和温度效应分析

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-12-08 DOI: 10.1016/j.engfracmech.2025.111773

Yue Guo , Jun Zhao , Xia-ting Feng , Shi-shu Zhang , Liang Hu

This study explores the influence of lateral stress (0 ∼ 50 MPa) and temperature (25 ∼ 280 ℃) on the shear mechanical behavior of rocks under the high temperature and high stress environments. The research analyzed the shear failure process and failure mode under lateral stresses of 0 MPa and 50 MPa. The true triaxial shear process was divided into three stages: the initial compression stage (Ⅰ), the shear compression stage (Ⅱ), and the shear failure stage (Ⅲ). The results indicate that in the initial compression stage (Ⅰ), the increase in temperature enhances both the normal and lateral compression deformation of granite. An increase in lateral stress suppresses the normal compression deformation and causes the lateral deformation to transition from expansion to compression. During the shear stage (Ⅱ + Ⅲ), temperature and lateral stress enhance the peak shear strength of granite and reducing the roughness of its shear fracture surface. The lateral stress level is increased to suppress lateral spalling, making the shear fracture surface smoother. Lateral spalling forms a failure mode dominated by tensile fracture, whereas the shear fracture surface is dominated by shear fracture. The effects of lateral stress and temperature can be summarized as strengthening the sample structure and being dominated by thermal expansion. The increase in strengths and control of failure modes were achieved by enhancing the bonding strength between particles, inhibiting the direction of crack propagation, and activating surface particles.

研究了高温高应力环境下，侧向应力（0 ~ 50 MPa）和温度（25 ~ 280℃）对岩石剪切力学行为的影响。研究分析了0 MPa和50 MPa侧应力作用下的剪切破坏过程和破坏模式。将真三轴剪切过程划分为初始压缩阶段（Ⅰ）、剪切压缩阶段（Ⅱ）和剪切破坏阶段（Ⅲ）三个阶段。结果表明：在初始压缩阶段（Ⅰ），温度的升高增强了花岗岩的正向和侧向压缩变形；侧向应力的增大抑制了正常的压缩变形，使侧向变形由膨胀向压缩过渡。在剪切阶段（Ⅱ+Ⅲ），温度和侧向应力提高了花岗岩的峰值抗剪强度，降低了其剪切断口的粗糙度。增加侧向应力水平，抑制横向剥落，使剪切断口表面更加光滑。横向剥落形成以拉伸断裂为主的破坏模式，而剪切断裂面则以剪切断裂为主。侧向应力和温度的作用可以概括为强化试样结构和以热膨胀为主。通过增强颗粒间的结合强度、抑制裂纹扩展方向和激活表面颗粒来实现强度的提高和破坏模式的控制。

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引用次数: 0

A phase-field regularization of porous–ductile fracture 多孔韧性断裂的相场正则化

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-12-08 DOI: 10.1016/j.engfracmech.2025.111783

D. Kavvadias , O. El Khatib , S.A. Patil , B. Kiefer , Th. Baxevanis

This work outlines a phase-field model for fracture in isotropic porous solids undergoing large plastic deformations. The formulation builds upon the Gurson–Tvergaard–Needleman (GTN) model, which links fracture micro-mechanisms, i.e., micro-crack nucleation, growth, and coalescence, to the final macro-scale rupture. While structurally similar to gradient-enhanced GTN models, it is instead based on a purely geometric regularization of void and crack discontinuities, i.e., transitions between material and void regions. In contrast to existing phase-field models of porous–ductile fracture – which employ the phase-field methodology to void coalescence and typically rely on an additional length scale introduced through non-local formulations of plasticity or porosity to address the loss of ellipticity in the governing equilibrium equations – the proposed approach applies a single-length-scale, phase-field regularization to the entire material response. The model is implemented in the ABAQUS finite element suite through a user-defined material subroutine (VUMAT), supporting explicit solvers. The phase-field variable is treated as a temperature-like field within ABAQUS’s coupled thermo-mechanical framework. Several boundary value problems are solved and experiments are simulated to demonstrate the robustness of the formulation and validate its numerical implementation and predictive accuracy.

这项工作概述了各向同性多孔固体在经历大塑性变形时断裂的相场模型。该公式建立在Gurson-Tvergaard-Needleman （GTN）模型的基础上，该模型将断裂的微观机制（即微裂纹成核、扩展和合并）与最终的宏观破裂联系起来。虽然在结构上类似于梯度增强GTN模型，但它是基于空洞和裂纹不连续的纯粹几何正则化，即材料和空洞区域之间的过渡。现有的多孔韧性断裂相场模型采用相场方法进行空洞聚并，通常依赖于通过塑性或孔隙率的非局部公式引入的额外长度尺度来解决控制平衡方程中椭圆性的损失，与之相反，所提出的方法对整个材料响应应用单一长度尺度、相场正则化。该模型通过用户定义的材料子程序（VUMAT）在ABAQUS有限元套件中实现，支持显式求解。相场变量在ABAQUS的热-力学耦合框架中被视为类温度场。通过对几个边值问题的求解和实验模拟，验证了该公式的鲁棒性，并验证了其数值实现和预测的准确性。

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引用次数: 0

Effect of curing age on the bonding performance of the interface between track slab concrete and self-compacting concrete 养护龄期对轨道板混凝土与自密实混凝土界面粘结性能的影响

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-12-07 DOI: 10.1016/j.engfracmech.2025.111751

Zhiwen An , Lei Qin , Chengchao Guo , Leiyang Pei , Feifan Shi , Fuming Wang

Accurately evaluating the evolution of interfacial bonding properties between track slabs and self-compacting concrete (SCC) filling layers over time is crucial. In this study, push-out tests were conducted on track slab concrete (TSC)–SCC composite specimens at different ages, and the acoustic emission (AE) technique was used to monitor the process. The results revealed that the interfacial shear strength of the 56-day specimen reached 1.275 MPa under a test loading rate of 0.01 MPa/s. Additionally, a predictive model for the shear strength of the TSC–SCC interface was established. The TSC–SCC specimens exhibited brittle failure under shear load. The sharp increase in AE ringing counts and energy showed the rapid development of interfacial damage. Both the conventional Japanese Construction Materials Standard method and the Gaussian Mixture Model algorithm effectively revealed the evolution of crack types in TSC–SCC specimens, and their trends and magnitudes of change were nearly identical. As the curing age increased, shear cracks became more prevalent while tensile cracks diminished. This change in the failure mode of the specimens can be attributed to the increased degree of cement hydration. This study offers a valuable reference for the design, operation, and maintenance of the CRTS III slab track.

准确评估轨道板与自密实混凝土（SCC）充填层之间界面粘结性能随时间的演变至关重要。本文对不同龄期的轨道板混凝土(TSC) -SCC复合材料试件进行了推挤试验，并利用声发射（AE）技术监测了这一过程。结果表明：试验加载速率为0.01 MPa/s时，56 d试样的界面抗剪强度达到1.275 MPa；建立了TSC-SCC界面抗剪强度预测模型。TSC-SCC试样在剪切作用下表现为脆性破坏。声发射振铃数和能量的急剧增加表明界面损伤迅速发展。传统的日本建筑材料标准方法和高斯混合模型算法都能有效地揭示TSC-SCC试件裂纹类型的演化，且两者的变化趋势和幅度几乎相同。随着龄期的增加，剪切裂纹增多，拉伸裂纹减少。这种破坏模式的变化可归因于水泥水化程度的增加。该研究为CRTS III型平板轨道的设计、运营和维护提供了有价值的参考。

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引用次数: 0

Are carbon fibres beneficial to improve mechanical and fracture properties of FDM printed composites? 碳纤维是否有利于改善FDM打印复合材料的机械和断裂性能？

IF 5.3 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-12-07 DOI: 10.1016/j.engfracmech.2025.111791

Estera Vălean , Liviu Marșavina , Sergiu-Valentin Galațanu , Pietro Foti , Filippo Berto

Fused Deposition Modeling (FDM) is currently the most accessible additive manufacturing technology due to its affordability and the simplicity of its machinery, coupled with the low cost and widespread availability of thermoplastic polymers. In this study, the mechanical properties of virgin thermoplastic materials (PLA and PETG) under bending and dynamic tests, as well as the impact of their carbon fiber reinforcement are investigated. All samples were manufactured under the same conditions using the same FDM machine. A study is also made on the tensile properties of the material wires, studying their morphology in detail in order to highlight possible signs that would reveal the nature of the influence of fiber reinforcement on the overall mechanical behavior of the printed components. The experimental results revealed contrasting effects of carbon fiber reinforcement on PLA and PETG. PLA-CF exhibited microcrack formation (crazing), which led to increased ductility but also to a decrease in tensile strength, flexural strength, and fracture toughness, indicating a general embrittlement of the composite. In contrast, PETG-CF showed improved mechanical and fracture properties compared to plain PETG, most likely due to better interfacial adhesion between the fibers and the polymer matrix, although with a more brittle behavior.

熔融沉积建模（FDM）是目前最容易获得的增材制造技术，因为它的价格合理，机器简单，再加上热塑性聚合物的低成本和广泛可用性。在本研究中，研究了原生热塑性材料（PLA和PETG）在弯曲和动态试验下的力学性能，以及碳纤维增强对其的影响。所有样品都是在相同条件下使用相同的FDM机器制造的。还对材料线的拉伸性能进行了研究，详细研究了它们的形态，以突出可能的迹象，揭示纤维增强对印刷部件的整体机械行为的影响的性质。实验结果显示了碳纤维增强对聚乳酸和PETG的影响。PLA-CF表现出微裂纹的形成（裂纹），这导致延展性增加，但也导致拉伸强度、弯曲强度和断裂韧性下降，表明复合材料普遍脆化。相比之下，与普通PETG相比，PETG- cf具有更好的力学和断裂性能，这很可能是由于纤维与聚合物基体之间的界面粘附性更好，尽管其脆性更大。

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