【新文速递】2024年10月11日复合材料SCI期刊最新文章

今日更新：Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 1 篇，Thin-Walled Structures 2 篇Journal of the Mechanics and Physics of SolidsAnalysis of mode I crack propagation in glassy polymers under cyclic loading using a molecular dynamics informed continuum model for crazingTobias Laschuetza, Thomas Seeligdoi:10.1016/j.jmps.2024.105901循环载荷作用下玻璃聚合物I型裂纹扩展的分子动力学连续介质模型分析Craze and crack propagation in glassy polymers under cyclic mode I loading are investigated by employing a recently developed continuum-micromechanical model for crazing. This model accounts for the local morphology change from microvoids to fibrils during craze initiation, viscoplastic drawing of bulk material into fibrils, and viscoelastic creep recovery of the fibrillated craze matter during unloading. To ensure consistency between the bulk and craze model parameters, the material parameters of the craze model are normalised and calibrated based on a hybrid approach integrating experimental findings from the literature and molecular dynamics results. This yields a generic, yet representative glassy polymer response. In the framework of 2D plane strain finite element simulations, we study brittle as well as ductile glassy polymers and assess the results by drawing comparisons to the experimental and numerical literature. For brittle materials, characterized by a purely elastic bulk behaviour, the model reproduces craze characteristics such as the craze opening contour, the craze length-to-width ratio, a double stress peak at the craze and crack tip, and a non-proportional stress redistribution during loading-unloading cycles. In ductile glassy polymers, the interaction of shear yielding in the bulk and crazing along the ligament is analysed. In particular, shear bands emanate from the crack tip in each loading cycle and arch forward towards the craze. This plastic zone shares resemblance to the so-called epsilon-shaped deformation zone. The current simulations capture normal fatigue crack propagation, where craze and crack growth occur near the peak load in every cycle and the craze length remains relatively constant across the loading cycles. Moreover, findings from this study suggest that plasticity-induced unloading of the craze adjacent to the crack tip impedes crack growth.采用最近发展的连续细观裂纹力学模型，研究了循环模式I加载下玻璃聚合物的裂纹和裂纹扩展。该模型考虑了开裂过程中由微孔到原纤维的局部形态变化、块状材料的粘塑性拉伸成原纤维以及卸载过程中纤维化开裂物质的粘弹性蠕变恢复。为了确保体积和裂纹模型参数之间的一致性，基于结合文献实验结果和分子动力学结果的混合方法，对裂纹模型的材料参数进行了归一化和校准。这产生了一个通用的，但代表性的玻璃聚合物反应。在二维平面应变有限元模拟的框架下，我们研究了脆性和延展性玻璃聚合物，并通过与实验和数值文献的比较来评估结果。对于以纯弹性体行为为特征的脆性材料，该模型再现了裂缝特征，如裂缝张开轮廓、裂缝长宽比、裂缝和裂纹尖端的双应力峰值以及加载-卸载循环期间的非比例应力重分布。在延性玻璃聚合物中，分析了块体剪切屈服与韧带裂纹的相互作用。特别是，剪切带在每个加载周期中从裂纹尖端发出，并向开裂方向拱起。这个塑性区与所谓的ε形变形区有相似之处。目前的模拟捕获了正常的疲劳裂纹扩展，在每个循环中，裂纹和裂纹扩展都发生在峰值载荷附近，并且在整个加载循环中，裂纹长度保持相对恒定。此外，本研究的结果表明，裂纹尖端附近裂纹的塑性卸载会阻碍裂纹的扩展。Mechanics of MaterialsNonlinear behavior simulation of ceramic-matrix composites using constituent-volume homogenization methodYuhan Zhao, Shaojing Dong, Xiuli Shendoi:10.1016/j.mechmat.2024.105179基于本构-体积均质法的陶瓷基复合材料非线性行为模拟The nonlinear behavior of ceramic-matrix composites is affected by interface debonding and fiber pull-out. In this paper, we propose the constituent-volume homogenization method (CVHM) to replace the conventional bundle homogenization method, in order to model the behavior of trans-element debonding in woven structures using finite element method. Based on the CVHM, we establish the elastic relation of the relative motion between the fiber and the matrix, and the elastic constitutive relations for the constituents. Methods have also been developed to calculate the microscopic local stress of bundle under pull-out and multiaxial loads. Based on the above studies, we develop a procedure to analyze the stress-strain relation of braided composites using the CVHM. To validate the proposed method, we estimate the nonlinear behavior of the 2D plain-weave ceramic-matrix composites and compare the results with experimental data. The influence of interface shear strength (ISS) and the fiber ultimate tensile strength (UTS) on the nonlinear behavior is investigated.陶瓷基复合材料的非线性行为受界面脱粘和纤维拔出的影响。为了用有限元方法模拟编织结构的跨单元脱粘行为，本文提出了用构件-体积均质法（CVHM）来代替传统的束均质法。在此基础上，建立了纤维与基体相对运动的弹性关系，以及构件的弹性本构关系。本文还研究了拉拔和多轴载荷作用下管束微观局部应力的计算方法。在此基础上，提出了一种利用CVHM分析编织复合材料应力-应变关系的方法。为了验证所提出的方法，我们估计了二维平面编织陶瓷基复合材料的非线性行为，并将结果与实验数据进行了比较。研究了界面抗剪强度（ISS）和纤维极限抗拉强度（UTS）对纤维非线性性能的影响。Thin-Walled StructuresProgressive collapse of beam-to-upright subassemblies of steel storage racks under a column removal scenarioLiusi Dai, Hao Yao, Shen Yan, Chong Rendoi:10.1016/j.tws.2024.112575在立柱移除的情况下，钢存储架的梁-直立组件的逐渐倒塌This paper presents an experimental investigation into progressive collapse behaviour of steel storage pallet racks under a column removal scenario. The double-half-span substructure is applied in experimental tests. A total of eight substructures are tested, considering two types of beam-to-upright connections, i.e., boltless and bolted connections, commonly used in pallet racks. Different upright profiles and thicknesses, varied beam heights, and the number of tabs are carefully considered in the tests, and their effects on progressive collapse behaviour of pallet racks are thus evaluated. In particular, the influence of pallet loads is carefully evaluated in this paper. Detailed experimental results of all specimens are provided, including the full-range force-displacement curves and the failure modes. The dominated failure modes observed in the tests are the combination of tab crack and bolt bearing failure leading to tearing of beam-end-connector (T+B), the combination of tab crack and bolt bearing failure leading to tearing of upright wall (T+C), and tab crack (T). The test results revealed that the presence of pallet loads greatly influences structural progressive collapse behaviour and thus should be considered in further studies. Moreover, in bolted connections, smaller beam heights and thinner column thicknesses exhibit better resistance against progressive collapse. Whereas in boltless connections, increasing the number of tabs enhances the resistance against progressive collapse. Generally, the bolted connections are proven to have better resistance against progressive collapse than boltless connections and can be used in storage racks to improve structural robustness.本文提出了一种试验研究的连续倒塌行为的钢仓储托盘货架在柱移除的情况下。试验中采用了双半跨子结构。考虑到两种类型的梁-直立连接，即无螺栓连接和螺栓连接，共测试了八个子结构，通常用于托盘架。在试验中仔细考虑了不同的垂直轮廓和厚度、不同的梁高度和标签数量，并因此评估了它们对托盘架的渐进倒塌行为的影响。特别地，本文仔细地评估了托盘载荷的影响。给出了所有试件的详细试验结果，包括全范围的力-位移曲线和破坏模式。试验中观察到的主要破坏模式是板卡裂纹和螺栓承载破坏导致梁端连接件撕裂（T+B），板卡裂纹和螺栓承载破坏导致直立墙体撕裂（T+C）和板卡裂纹(T)。试验结果表明，托盘荷载的存在对结构的渐进破坏行为有很大影响，应在进一步的研究中加以考虑。此外，在螺栓连接中，较小的梁高和较薄的柱厚表现出更好的抗连续倒塌能力。而在无螺栓连接中，增加卡箍的数量可以增强抗逐渐坍塌的能力。一般来说，螺栓连接被证明比无螺栓连接具有更好的抗逐渐倒塌能力，可以用于存储货架，以提高结构的稳健性。Creep relaxation to relieve residual stress in girth-butt welded X80 pipelines: Simulation and experimentXiaoguang Huang, Hehe Liu, Chang Huang, Jiren Cui, Zhenxiong Xiao, Xiuxing Zhudoi:10.1016/j.tws.2024.112597X80环对接焊接管道蠕变松弛消除残余应力：模拟与实验The residual stress in girth-butt weld presents safety risks for large-diameter oil-gas pipelines, necessitating an in-depth investigation into the welding residual stress and the development of effective methods to mitigate these stresses, thereby enhancing structural integrity. In this work, a finite element girth-butt welding model was developed to predict the residual stress of X80 pipelines. The residual stress relief resulting from local post-weld heat treatment (PWHT) was simulated based on the Norton creep model applicable to X80 steel. The simulation results, encompassing the residual stress both before and after PWHT, were validated through blind-hole drilling measurements. The results demonstrate that the welding residual stresses across all orientations were significantly reduced following PWHT, with a maximum stress reduction of approximately 360 MPa. The primary mechanical mechanism for residual stress relief was identified as high-temperature creep, and it was concluded that the PWHT alleviated welding residual stress effectively when the heating temperature exceeded the creep activation temperature. The consistency between the finite element analysis results and the experimentally measured residual stresses affirms the validity and feasibility of the finite-element-based approach for predicting welding residual stresses.大直径油气管道环对接焊缝残余应力存在安全隐患，需要对焊接残余应力进行深入研究，并开发有效的方法来降低这些应力，从而提高结构的完整性。为预测X80管道的残余应力，建立了环对接焊接有限元模型。采用适用于X80钢的Norton蠕变模型，对局部焊后热处理残余应力进行了数值模拟。模拟结果包含了PWHT前后的残余应力，并通过盲孔钻井测量进行了验证。结果表明，PWHT后各方向的焊接残余应力均显著降低，最大应力降低约360 MPa。高温蠕变是残余应力消除的主要机制，当加热温度超过蠕变激活温度时，PWHT能有效缓解焊接残余应力。有限元分析结果与实验测量的残余应力吻合，证实了基于有限元的焊接残余应力预测方法的有效性和可行性。来源：复合材料力学仿真Composites FEM