今日更新：Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇，Computer Methods in Applied Mechanics and Engineering 1 篇，Thin-Walled Structures 2 篇Journal of the Mechanics and Physics of SolidsA finite crack growth energy release rate for elastic-plastic fractureXu Wu, Ren Yanshen, Xiao Si, Liu Bindoi:10.1016/j.jmps.2023.105447弹性塑性断裂的有限裂纹生长能量释放率The concept of energy release rate proposed by Griffith originally used for elastic brittle material was extended for ductile material by Irwin and Orowan using the sum of the surface energy and the work of plastic dissipation as fracture resistance. This fracture resistance, however, depends on the load type and specimen geometry, which hinders its wide application. In contrast, in this paper, a finite crack growth energy release rate is proposed by assuming a finite crack growth, which is conveniently applicable to finite element analysis. The effect of the plastic dissipation on the crack growth is considered in the driving force. Elastic-plastic finite element analysis is used to apply the present energy release rate. Compared to the experiment results, it is shown that for a fixed finite crack growth, a constant critical energy release rate can well predict the stable crack growths and residual strengths of sheets with single and various collinear cracks subjected to different types of loads. The present finite crack growth energy release rate is conceptually simple, has a solid physical foundation, and would be appealing for ductile crack growth analysis.格里菲斯提出的能量释放率概念最初用于弹性脆性材料，后来由 Irwin 和 Orowan 扩展到韧性材料，使用表面能和塑性耗散功的总和作为断裂阻力。然而，这种断裂阻力取决于载荷类型和试样几何形状，这阻碍了它的广泛应用。相比之下，本文通过假设有限裂纹生长，提出了有限裂纹生长能量释放率，方便地应用于有限元分析。在驱动力中考虑了塑性耗散对裂纹生长的影响。采用弹塑性有限元分析来应用当前的能量释放率。实验结果表明，与实验结果相比，对于固定的有限裂纹生长，恒定的临界能量释放率可以很好地预测板材在不同类型载荷作用下的稳定裂纹生长和残余强度。本有限裂纹生长能量释放率概念简单，具有坚实的物理基础，可用于韧性裂纹生长分析。Mechanics of MaterialsEffects of the graphene/metal interface on elastic properties of Cu and W matrices: Molecular dynamics simulationWang Xin, Xu Ruoyu, Zhou Mingyu, Matharage Shanika Yasantha, Zhou Yuzhen, Wang Zhongdongdoi:10.1016/j.mechmat.2023.104815石墨烯/金属界面对铜和瓦基体弹性特性的影响：分子动力学模拟The present study aimed to investigate the effects of graphene/metal interface on the elastic properties of Cu and W matrices over a wide range of temperatures through molecular dynamics (MD) simulations. Results showed that the addition of graphene to Cu and W matrices can improve their Young's moduli, with higher enhancements observed at higher graphene fractions. The load transfer mechanism was employed to analyse the reinforcing effect of graphene in metal matrices, and the load transfer rates were subsequently calculated. The strengthening effect of graphene in Cu matrix was observed to increase significantly with rising temperatures, whereas that of G-W models decreased due to the decreasing load-carrying capacity of graphene at very high temperatures. Furthermore, the Poisson's ratio of Cu-based materials decreased with increasing strain, while that of W-based materials remained nearly constant. This behaviour can be attributed to the prominent surface effect of lateral stress and the crystal structure transformation observed in Cu-based materials. Notably, a negative Poisson's ratio was observed in G-Cu nanoplate when the vertical stress became compressive. Overall, this study provides insights into the elastic deformation behaviour of graphene/metal composites, which could help develop new graphene-reinforced Cu or W composites.本研究旨在通过分子动力学（MD）模拟，研究石墨烯/金属界面在宽温度范围内对铜和钨基体弹性特性的影响。结果表明，在 Cu 和 W 基体中添加石墨烯可提高它们的杨氏模量，石墨烯含量越高，提高幅度越大。利用载荷传递机制分析了石墨烯在金属基体中的增强效应，随后计算了载荷传递率。据观察，石墨烯在铜基体中的增强效应随着温度的升高而显著增强，而 G-W 模型的增强效应则由于石墨烯在极高温下的承载能力下降而减弱。此外，随着应变的增加，铜基材料的泊松比降低，而 W 基材料的泊松比几乎保持不变。这种行为可归因于横向应力的突出表面效应以及在铜基材料中观察到的晶体结构转变。值得注意的是，当垂直应力变为压缩应力时，在 G-Cu 纳米板中观察到负泊松比。总之，本研究为石墨烯/金属复合材料的弹性变形行为提供了深入见解，有助于开发新型石墨烯增强铜或瓦复合材料。International Journal of PlasticityThree-dimensional configuration of crystal plasticity in stainless steel assessed by high resolution digital image correlation and confocal microscopyYin Wujun, Briffod Fabien, Hu Haoyu, Shiraiwa Takayuki, Enoki Manabudoi:10.1016/j.ijplas.2023.103762通过高分辨率数字图像相关性和共聚焦显微镜评估不锈钢晶体塑性的三维构造In polycrystalline austenitic stainless steels, a comprehensive three-dimensional configuration of crystal plasticity in relation to microstructure is required to elucidate the deformation behaviors during mechanical loading. In the present work, a combination of backscattered electron image (BSE) based high-resolution digital image correlation (HR-DIC) and laser scanning confocal microscopy (LSCM) was employed to simultaneously investigate in-plane and out-of-plane deformations at the sub-grain scale in 316 stainless steel. The high spatial resolution and precise alignment provided by the three-dimensional deformation assessment enable the identification of specific slip and twinning systems. This is achieved through the minimization of the residual L2 norm between the in-plane components of experimental and theoretical strain tensors. Dominant slip and few mechanical twinning activities are initiated at the early-stage of yielding, and their frequency and intensity increase with the applied load. The hierarchical networks formed by nanotwins, along with the presence of grain and annealing twin boundaries, serve as obstacles for slip glide, leading to substantial twin-slip interaction and grain boundary strengthening. As a consequence of wide mechanical twins formed by parallel nanotwins coalescence and strain localization at the twin boundary, slip transmission occurs, resulting in an effective accommodation of external stress. Furthermore, the consistent observation of out-of-plane roughness, in alignment with twinning Burgers vector predictions, offers valuable insights into the significant deformation gradient occurring in the vicinity of boundaries. This deformation gradient is influenced by the neighboring mechanical twinning activities, indicating strong obstacle to twin transmission and high back-stresses resulting from the highly misoriented grain boundary.在多晶奥氏体不锈钢中，需要对晶体塑性与微观结构的关系进行全面的三维配置，以阐明机械加载过程中的变形行为。本研究采用基于背散射电子图像（BSE）的高分辨率数字图像相关（HR-DIC）和激光扫描共聚焦显微镜（LSCM）相结合的方法，同时研究 316 不锈钢亚晶粒尺度的面内和面外变形。三维形变评估所提供的高空间分辨率和精确对准可识别特定的滑移和孪生系统。这是通过最小化实验应变张量和理论应变张量平面内分量之间的残余 L2 准则来实现的。主要的滑移和少量的机械孪生活动在屈服的早期阶段就已开始，其频率和强度随着施加载荷的增加而增加。纳米孪晶形成的分层网络以及晶界和退火孪晶边界的存在成为滑移滑行的障碍，导致大量的孪晶滑移相互作用和晶界强化。由于平行纳米晶丝凝聚形成的宽机械孪晶以及孪晶边界的应变局部化，滑移传递发生了，从而有效地容纳了外部应力。此外，平面外粗糙度的一致观察结果与孪晶布尔格斯矢量的预测结果一致，为了解边界附近发生的显著变形梯度提供了宝贵的见解。这种变形梯度受到邻近机械孪晶活动的影响，表明孪晶传递存在强大障碍，高度错向晶界产生了高背应力。Computer Methods in Applied Mechanics and EngineeringExtension of methods based on the stabilized finite element formulation for the solution of the Navier–Stokes equations and application to aerodynamic designChalot F., Johan Z., Mallet M., Billard F., Martin L., Barré S.doi:10.1016/j.cma.2023.116425基于稳定有限元公式的纳维-斯托克斯方程求解方法的扩展及在空气动力学设计中的应用Accurate and fast simulation-based processes are key to the design of future aircraft. Computational Fluid Dynamic technology at Dassault Aviation relies on numerical formulations developed by T.J.R. Hughes. Continued efforts over the past years have led to impressive capability and new tools that are applied to the design of both long-range business jets and military aircraft. Recent advances are related to multidisciplinary design technology and to complex flow physics associated to turbulence and transition phenomena. This paper will present a number of examples to illustrate these new capabilities. Methods developed for the flutter analysis of configurations with complex flow features will be discussed. Aerodynamic simulations required for structural fatigue analysis will also be presented. Finally, complex thermodynamics capabilities will be illustrated.精确、快速的模拟程序是未来飞机设计的关键。达索航空公司的计算流体力学技术依赖于 T.J.R. Hughes 开发的数值公式。经过多年的不懈努力，计算流体力学技术已经具备了令人印象深刻的能力，并开发出新的工具，应用于远程公务喷气机和军用飞机的设计。最近的进步与多学科设计技术以及与湍流和过渡现象相关的复杂流动物理有关。本文将举例说明这些新功能。将讨论为分析具有复杂流动特征的配置而开发的方法。还将介绍结构疲劳分析所需的空气动力学模拟。最后，还将说明复杂热力学功能。Thin-Walled StructuresThermo-mechanical analysis of functionally graded nickel/titanium alloys under different process parameters of directed energy depositionLi Zhi-Jian, Xiao Peng, Dai Hong-Liang, Luo Wei-Feng, Du Chong, Tong Zhi-Fengdoi:10.1016/j.tws.2023.111235不同定向能沉积工艺参数下功能分级镍/钛合金的热机械分析The build-up of residual stress and porosity plays an important role in the mechanical properties of as-built parts during directed energy deposition (DED). However, the thermo-mechanical behavior of functionally graded nickel/titanium alloys (FGNTAs) in the DED process remains unclear. In this study, a computationally efficient thermo-mechanical coupled model of DED-printed FGNTAs with different porosities is developed. The temperature-dependent effective material properties of FGNTAs are first determined based on the rule of mixture. Subsequently, the temperature, residual stress, and deformation fields within as-built FGNTAs are predicted using the differential quadrature method. The predicted results show excellent agreement with the predictions and experimental data in the literature. Furthermore, the effect of key parameters on the thermo-mechanical responses of DED-printed FGNTAs is investigated, including energy density, porosity distributions, part dimensions, temperature settings, and structural modes. The results show that the residual stress and vertical deflection increase with the higher energy input, length-to-width ratio, and evener porosity distributions, while decreasing with larger porosity, preheating as well environment temperatures, external loads, and power index. These results can provide a useful guideline for the design and manufacturing of high-quality FGNTAs during DED.在定向能量沉积（DED）过程中，残余应力和孔隙率的积累对竣工部件的机械性能起着重要作用。然而，功能分级镍/钛合金 (FGNTA) 在定向能沉积过程中的热机械行为仍不清楚。在本研究中，我们建立了一个具有不同孔隙率的 DED 印刷 FGNTA 的高效热机械耦合计算模型。首先根据混合法则确定了 FGNTA 随温度变化的有效材料特性。随后，使用微分正交法预测了竣工 FGNTA 内的温度场、残余应力场和变形场。预测结果与文献中的预测和实验数据非常吻合。此外，还研究了关键参数对 DED 印刷 FGNTA 热机械响应的影响，包括能量密度、孔隙率分布、零件尺寸、温度设置和结构模式。结果表明，残余应力和垂直挠度随着能量输入、长宽比和孔隙率分布的增大而增大，而随着孔隙率增大、预热以及环境温度、外部负载和功率指数的增大而减小。这些结果可为在 DED 过程中设计和制造高质量的 FGNTA 提供有用的指导。Shear capacity of PVC-CFRP confined concrete column-RC beam interior joint strengthened with core steel tubeYu Feng, Fang Yuan, Feng Chaochao, Tan Siyong, Wang Yandoi:10.1016/j.tws.2023.111213用核心钢管加固的 PVC-CFRP 混凝土柱-RC 梁内部连接处的抗剪能力This paper presents an experimental investigation on polyvinyl chloride (PVC)-carbon fiber reinforced polymer (CFRP) confined concrete (PCCC) column-RC beam interior joint strengthened with core steel tube (CST). Thirteen interior joints are designed and tested under low cyclic loading considering the impacts of six variables, such as diameter-thickness ratio of CST, stirrup ratio of joint, axial compression ratio, CFRP strips spacing, reinforcement ratio of beam and reinforcement ratio of column. Distinct shear deformation in joint region finally dominates the failure of specimens. The load-displacement hysteretic curves are relatively full and eventually show inverse S shape, indicating the specimens have considerable seismic behavior and energy dissipation capacity. The yield and peak shear capacities increase as diameter-thickness ratio, stirrup ratio of joint, reinforcement ratio of column or reinforcement ratio of beam increases. Comparatively, the axial compression ratio and CFRP strips spacing exert less influence on shear capacity. Considering the impact of diameter-thickness ratio, stirrup ratio of joint and reinforcement ratio of column, a formula for estimating shear capacity of PCCC column-RC beam interior joints strengthened with CST is proposed and its accuracy is verified by test data.本文介绍了用核心钢管（CST）加固的聚氯乙烯（PVC）-碳纤维增强聚合物（CFRP）约束混凝土（PCCC）柱-RC 梁内部连接的实验研究。考虑到 CST 直径-厚度比、接头箍筋比、轴向压缩比、CFRP 带间距、梁配筋率和柱配筋率等六个变量的影响，在低循环荷载下设计并测试了 13 个内部接头。连接区域明显的剪切变形最终主导了试样的破坏。荷载-位移滞回曲线相对饱满，最终呈反 S 型，表明试件具有相当的抗震性能和耗能能力。随着直径-厚度比、连接箍筋比、柱配筋比或梁配筋比的增大，屈服承载力和峰值剪切承载力也随之增大。相比之下，轴向压缩比和 CFRP 带间距对剪切能力的影响较小。考虑到直径-厚度比、接头箍筋比和柱配筋比的影响，提出了用 CST 加固的 PCCC 柱-RC 梁内部接头的抗剪承载力估算公式，并通过试验数据验证了其准确性。来源：复合材料力学仿真Composites FEM
