【新文速递】2024年5月10日复合材料SCI期刊最新文章

今日更新：International Journal of Solids and Structures 1 篇，Journal of the Mechanics and Physics of Solids 2 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇International Journal of Solids and StructuresEffect of a subsurface void on the micromechanics of ductile metal indentation using remeshingDebasree Das, Narayan K. Sundaramdoi:10.1016/j.ijsolstr.2024.112842利用重网格法研究地下空洞对延性金属压痕微观力学的影响Near-surface voids and pores are generated in metal processing operations as diverse as additive manufacturing and powder processing, but their effect on indentation hardness has not been explored outside homogenized frameworks. Here we model the micromechanics of near-surface void deformation up to closure in a wedge-indentation field in ductile metal, and reveal the considerable softening effect of voids on the indentation hardness. Both symmetrically and eccentrically located voids, at various depths below the free surface, are studied. Notably, the extent of apparent reduction in the elastic modulus due to a void is much smaller than its effect on apparent hardness, e.g. 6.5% against 55% for the same void. Critical to the simulations is an adaptive remeshing finite element (FE) framework that allows accurate capture of processes like void closure and void-wall self-contact. The simulations reveal the subsurface plastic strain, strain-rate, and velocity fields with high fidelity, and their radical differences from the radial indentation field in a void-free specimen. These differences include the presence of localized pockets of high and low strain, and the initial accommodation of material displaced by the indenter by a corresponding reduction in void area. Unlike voids under uniform compression, the void-area evolution in indentation shows a characteristic sigmoidal pattern of reduction with indentation depth for all but the smallest voids. Interestingly, the indented surface profile can exhibit a one-sided pile-up feature which is diagnostic of the presence of an eccentrically located sub-surface void. Our remeshing scheme is versatile, as exemplified by its ability to model the extreme deformation associated with two nearly closed-spaced voids under an indenter. Our work shows that void-closure simulations in related applications like forming could benefit from the adoption of a remeshing framework.在增材制造和粉末加工等多种金属加工操作中都会产生近表面空洞和孔隙，但它们对压痕硬度的影响尚未在均质框架之外进行过探索。本文模拟了延性金属楔压痕场中近表面孔洞变形直至闭合的微观力学过程，揭示了孔洞对压痕硬度的显著软化作用。研究了自由表面以下不同深度的对称和偏心位置的空洞。值得注意的是，空穴对弹性模量的明显降低程度远远小于其对表观硬度的影响，例如，相同空穴对表观硬度的影响为6.5%对55%。模拟的关键是自适应网格有限元(FE)框架，该框架允许准确捕获空隙闭合和空隙壁自接触等过程。模拟结果显示了高逼真度的亚表面塑性应变场、应变速率场和速度场，以及它们与无空洞试样径向压痕场的根本差异。这些差异包括高应变和低应变的局部口袋的存在，以及通过相应的空隙面积减少，压头位移的材料的初始容纳。与均匀压缩条件下的孔洞不同，除最小孔洞外，压痕中孔洞面积随压痕深度的增加呈显著的s型变化。有趣的是，凹陷的表面轮廓可以表现出片面的堆积特征，这是对偏心位置的地下空洞存在的诊断。我们的网格重新划分方案是通用的，例如它能够模拟与压头下两个几乎封闭的空隙相关的极端变形。我们的工作表明，在成型等相关应用中的空隙闭合模拟可以从采用重网格框架中受益。Journal of the Mechanics and Physics of SolidsEffective thermodynamic potentials and internal variables: Linear viscoelastic compositesNoel Lahellec, Renaud Masson, Pierre Suquetdoi:10.1016/j.jmps.2024.105649有效热力学势和内部变量:线性粘弹性复合材料New theoretical relations in linear viscoelasticity are derived by combining two different points of view. On the one hand, the general thermodynamic framework makes it possible to define the energy stored and the energy dissipated in linearly viscoelastic composites. On the other hand, the correspondence principle permits to express the macroscopic strain-stress relation as ordinary differential equations for a set of effective internal variables. A finite and small number of internal variables is rigorously sufficient in several cases of interest, including in particular particulate composites. Interpreting the macroscopic response as a rheological generalized Maxwell model allows us to compute the macroscopic free and dissipated energy of the composite. This interpretation is proved to be exact in several cases of interest. Coupled with Hashin–Shtrikman estimates, these thermodynamic functions provide additional information on the statistics of the field within each individual phase of the composite.结合两种不同的观点，导出了线性粘弹性的新理论关系。一方面，一般的热力学框架使得可以定义线性粘弹性复合材料中储存的能量和耗散的能量。另一方面，对应原理允许将宏观应变-应力关系表示为一组有效内变量的常微分方程。有限和少量的内部变量在一些情况下是严格充分的，包括在特定的颗粒复合材料。将宏观响应解释为流变广义麦克斯韦模型使我们能够计算复合材料的宏观自由能和耗散能。这种解释在几个有趣的案例中被证明是准确的。结合Hashin-Shtrikman估计，这些热力学函数提供了复合材料每个单独相内的场统计信息的附加信息。Quantifying the mechanical degradation of solid oxide cells based on 3D reconstructions of the real microstructure using a unified multiphysics coupling numerical frameworkYunpeng Su, Keda Ren, Zehua Pan, Jingyi Wang, Zheng Zhong, Zhenjun Jiaodoi:10.1016/j.jmps.2024.105654 使用统一的多物理场耦合数值框架，基于真实微观结构的三维重建来量化固体氧化物电池的力学退化In this work, a multiphysics coupling numerical framework is developed to quantitatively investigate the initial performances of solid oxide cells (SOCs) based on the thermodynamically consistent integration of the finite element method (FEM) and the phase field method (PFM) to reveal the interaction between species-defect transport, electrochemical reaction kinetics, stress and mechanical damage in SOC electrodes. The modeling framework is validated by comparing the simulation results based on real 3D microstructure reconstructions of specific SOCs with the experimental measurements in electrolysis and fuel cell modes. The phenomena of internal microstructure fracture and delamination observed in the experiment thus can be numerically modeled to quantify the effects of thermal and chemical stresses on the mechanical degradation of heterogeneous electrodes. The framework is also applied in the cross-scale quantification of the possible mechanical damage in SOCs subjected to different mechanical boundary conditions. The framework proposed in this work is flexible, can be superimposed with other fields, and incorporates input from cross-scale simulations. It provides a great potential platform for the optimization of future energy devices considering actual operating conditions and fills the gap in theoretical multiphysics modeling in the field of SOCs.在这项工作中，基于有限元法(FEM)和相场法(PFM)的热力学一致积分，开发了一个多物理场耦合数值框架来定量研究固体氧化物电池(SOC)的初始性能，以揭示SOC电极中物质缺陷传输、电化学反应动力学、应力和机械损伤之间的相互作用。通过将特定soc的真实三维微观结构重建的仿真结果与电解和燃料电池模式下的实验测量结果进行比较，验证了建模框架的有效性。因此，实验中观察到的内部微观结构断裂和分层现象可以通过数值模拟来量化热应力和化学应力对非均质电极机械降解的影响。该框架还应用于不同力学边界条件下soc可能发生的力学损伤的跨尺度量化。本工作提出的框架具有灵活性，可以与其他领域叠加，并包含来自跨尺度模拟的输入。它为考虑实际运行条件的未来能源器件的优化提供了一个极具潜力的平台，填补了soc领域理论多物理场建模的空白。Mechanics of MaterialsIdentifying multiple synergistic factors on the susceptibility to stress relaxation cracking in variously heat-treated weldmentsYi Yang, Dong Han, Wei Zhang, Yanfei Gao, Jorge Penso, Zhili Fengdoi:10.1016/j.mechmat.2024.105013确定了影响不同热处理焊件应力松弛开裂易感性的多种协同因素The 347H austenitic stainless steel has been widely used for pressure vessels and pipeline (PVP) applications due to its excellent creep and corrosion resistance, which fit ideally to the harsh conditions in petrochemical industries, fossil fuel or nuclear power plants, and modern energy storages. However, a failure mode has been commonly observed with cracks emerging at the heat affected zone (HAZ) of weldments during post-weld heat treatment (PWHT) or under intermediate to high temperature service conditions. This phenomenon is termed as Stress Relaxation Cracking (SRC) since the purpose of PWHT is to relieve the welding-induced residual stress fields, or as Stress Age Cracking (SAC) if failure happens during service. A leading literature explanation of this failure suggests that the residual stress relaxation and the precipitation dissolution and/or re-precipitation occur in the same temperature range, which can lead to locally high strains and thus to crack at the grain boundaries. Since in situ spatial measurements of residual stress fields, microstructural evolution, and failure processes are nearly infeasible, this work recourses to a micromechanical finite element framework that models the high temperature failure as the nucleation and growth of grain boundary cavities, whereas various parameters such as thermomechanical loading history and its evolution, the competition of grain-interior dislocation creep and grain-boundary diffusion in failure lifetime, and microstructural heterogeneities (such as the precipitate free zone near grain boundaries) can be quantitatively incorporated. It can be concluded from these microstructure-explicit simulations that an accurate knowledge of residual stress evolution and a carefully calibrated set of material constitutive parameters are the essential prerequisites for lifetime predictions. The understanding of individual governing factors also leads to a mechanistic interpretation of the observed SRC susceptibility C-curves. These results suggest that the criticality of residual stress evolution, but not the precipitation-induced local strains, be the leading factor for SRC.347H奥氏体不锈钢因其优异的抗蠕变和耐腐蚀性而广泛用于压力容器和管道(PVP)应用，非常适合石化工业，化石燃料或核电站以及现代能源储存的恶劣条件。然而，在焊后热处理(PWHT)或中高温使用条件下，焊接件的热影响区(HAZ)出现裂纹是一种常见的失效模式。这种现象被称为应力松弛开裂(SRC)，因为PWHT的目的是消除焊接引起的残余应力场，或者在使用过程中发生失效时称为应力时效开裂(SAC)。对这种破坏的主要文献解释认为，残余应力松弛和析出溶解和/或再析出发生在同一温度范围内，这可能导致局部高应变，从而在晶界处开裂。由于对残余应力场、微观组织演变和破坏过程的原位空间测量几乎是不可实现的，因此本研究采用微力学有限元框架，将高温破坏模拟为晶界空腔的形核和生长，而各种参数，如热力学加载历史及其演变、晶粒内部位错蠕变和晶界扩散在破坏寿命中的竞争，显微组织的非均质性(如晶界附近的无析出带)可以定量地纳入。从这些微观结构模拟可以得出结论，残余应力演化的准确知识和精心校准的材料本构参数集是寿命预测的必要先决条件。对个体控制因素的理解也导致了对观察到的SRC敏感性c曲线的机制解释。这些结果表明，残余应力演化的临界性，而不是降水引起的局部应变，是导致SRC的主要因素。International Journal of PlasticityTuning chemical short-range order for simultaneous strength and toughness enhancement in NiCoCr medium-entropy alloysSiyao Shuang, Yanan Hu, Xiaotao Li, Fuping Yuan, Guozheng Kang, Huajian Gao, Xu Zhangdoi:10.1016/j.ijplas.2024.103980调节NiCoCr中熵合金强度和韧性同时增强的化学短程顺序The pursuit of enhancing strength and toughness remains a critical endeavor in the field of structural materials. This study explores two distinct strategies to overcome the traditional strength-toughness trade-off. Specifically, we manipulate the chemical composition and short-range order (SRO) of the NiCoCr medium-entropy alloy, which has shown remarkable fracture toughness in recent experiments. Utilizing molecular dynamics simulations, we uncover nano-scale deformation mechanisms during crack propagation. Our findings highlight that optimizing the SRO degree leads to improvements in both atomic scale strength and toughness defined as the area underneath stress-strain curves from MD simulations. In contrast, a trade-off between strength and toughness persists when only manipulating the Ni content in the NiCoCr alloy. Based on the simulation results, we establish a strong correlation between toughness, strength, surface energies, and unstable stacking fault energies. These factors are influenced by the chemical composition and SROs in NiCoCr, with SROs acting as strong obstacles to dislocations, thereby contributing to additional strength. The exceptional toughness of NiCoCr with SRO arises from a synergy of intrinsic and extrinsic mechanisms, including dislocation glide, nanobridging during nanovoid coalescence and zigzag crack path. It is found that, in the presence of SRO, intrinsic toughening mechanisms usually associated with crack tip blunting and dissipation can also facilitate the onset of extrinsic toughening mechanisms of nanobridging and zig-zag crack path associated with nanovoid formation and coalescence. This study emphasizes the importance of tailoring SRO in designing materials with enhanced strength and toughness.提高材料的强度和韧性仍然是结构材料领域的一个重要课题。本研究探讨了两种不同的策略来克服传统的强度-韧性权衡。具体来说，我们在最近的实验中对NiCoCr中熵合金的化学成分和短程有序度(SRO)进行了控制，该合金在最近的实验中表现出了显著的断裂韧性。利用分子动力学模拟，我们揭示了裂纹扩展过程中的纳米级变形机制。我们的研究结果强调，优化SRO程度导致原子尺度强度和韧性的提高，原子尺度强度和韧性定义为MD模拟的应力-应变曲线下的区域。相反，当仅控制NiCoCr合金中的Ni含量时，强度和韧性之间的权衡仍然存在。基于模拟结果，我们建立了韧性、强度、表面能和不稳定层错能之间的强相关性。这些因素受到NiCoCr中的化学成分和sro的影响，sro作为位错的强大障碍，从而有助于增加强度。具有SRO的NiCoCr具有优异的韧性，这是由位错滑动、纳米空洞合并过程中的纳米桥接和锯齿裂纹路径等内在和外在机制共同作用的结果。研究发现，在SRO存在的情况下，通常与裂纹尖端钝化和耗散有关的内在增韧机制也可以促进与纳米孔洞形成和聚并有关的纳米桥接和锯齿形裂纹路径的外在增韧机制的发生。本研究强调了裁剪SRO在设计增强强度和韧性的材料中的重要性。来源：复合材料力学仿真Composites FEM