【新文速递】2024年6月18日固体力学SCI期刊最新文章

今日更新：International Journal of Solids and Structures 2 篇，Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 1 篇International Journal of Solids and StructuresComputational homogenization of the elastic properties of polycrystalline fcc metals within Mindlin’s second strain-gradient theoryV. Bagherpour, M.R. Delfanidoi:10.1016/j.ijsolstr.2024.112942明德林第二应变梯度理论中多晶 fcc 金属弹性特性的计算均质化The lack of interest in Mindlin’s second strain-gradient theory, despite its success in characterizing various phenomena for which there is no explanation in the classical elasticity, is predominantly due to the numerous higher-order elastic constants involved therein. As an attempt to overcome this shortcoming, a computational homogenization method for determining such elastic constants of polycrystalline face-centered cubic (fcc) metals is proposed in the present study. In this homogenization method, using the Voigt-type averaging scheme, a polycrystalline material is modeled by an isotropic aggregate of randomly oriented single crystals without accounting for the grain size effect and the complexities due to grain boundaries and junctions Subsequently, analytical expressions for the strain energy due to certain modes of loading are determined, and molecular simulations of a few fcc metals under such modes of loading are performed. Then, by fitting the corresponding analytical expressions to the results obtained from these simulations, the effective elastic constants and consequently the effective characteristic lengths of the fcc metals in their polycrystalline form are determined. Moreover, the free-surface-induced reconstruction in a thin layer of a solid is addressed both analytically and by molecular simulations, as a result of which the effective moduli of cohesion of the fcc metals in their polycrystalline form are calculated. In addition, the complete set of conditions for the positive-definiteness of the strain–energy-density function of isotropic materials within the adopted theory is derived, and subsequently a discussion of whether or not the numerical values obtained for the effective elastic moduli of the polycrystalline fcc metals satisfy such conditions is provided.尽管明德林的第二应变梯度理论成功地描述了经典弹性理论无法解释的各种现象，但人们对它缺乏兴趣，这主要是由于其中涉及大量高阶弹性常数。为了克服这一缺陷，本研究提出了一种计算均质化方法，用于确定多晶面心立方（fcc）金属的此类弹性常数。在这种均质化方法中，使用 Voigt 型平均方案，将多晶材料建模为随机取向单晶的各向同性集 合体，而不考虑晶粒大小效应以及晶界和交界引起的复杂性。然后，通过将相应的分析表达式与这些模拟结果进行拟合，确定了多晶态 fcc 金属的有效弹性常数和有效特征长度。此外，还通过分析和分子模拟解决了固体薄层中的自由表面诱导重构问题，并由此计算出了多晶形式 fcc 金属的有效内聚模量。此外，还推导出在所采用的理论中各向同性材料应变能量密度函数正定义的整套条件，并随后讨论了所获得的多晶 fcc 金属有效弹性模量数值是否满足这些条件。A machine learning assisted multifidelity modelling methodology to predict 3D stresses in the vicinity of design features in composite structuresOmar A.I. Azeem, Silvestre T. Pinhodoi:10.1016/j.ijsolstr.2024.112946 机器学习辅助多保真度建模方法，用于预测复合材料结构设计特征附近的三维应力Multifidelity global–local finite element (FE) analyses are typically used to predict damage initiation hotspots around repetitive design features in large composite structures, such as composite airframes. We propose the use of machine learning (ML) methods to accelerate these analyses. We demonstrate this ML assisted framework for the stress analysis of a hole in plate feature in an aerospace C-spar structure. To enable this framework, we develop the following original features: a computationally efficient sampling scheme; a work-equivalent boundary condition homogenisation scheme; a volume averaged ply-by-ply stress approach; and a sequential long-short term memory neural network reformulated from a time basis to a stacking sequence basis with further bi-directionality customisation. Overall, we show that the developed method results in high-accuracy prediction of 3D stresses, with over two orders of magnitude reduction in modelling and simulation time compared to FE analyses.多保真度全局-局部有限元（FE）分析通常用于预测大型复合材料结构（如复合材料机身）中重复设计特征周围的损伤起始热点。我们建议使用机器学习（ML）方法来加速这些分析。我们演示了这一 ML 辅助框架，用于航空航天 C 型支柱结构中板孔特征的应力分析。为了实现这一框架，我们开发了以下原创功能：计算效率高的采样方案；功当量边界条件均质化方案；体积平均逐层应力方法；以及从时间基础到堆叠序列基础的顺序长短期记忆神经网络，并进一步进行了双向定制。总之，我们表明所开发的方法可实现高精度的三维应力预测，与 FE 分析相比，建模和模拟时间减少了两个数量级以上。Journal of the Mechanics and Physics of SolidsWrinkle-free membranes through spatioselective exposureGuangliang Qi, Heng Gao, Jianyue Wang, Guozhong Zhao, Dzianis Marmysh, Zhan Kang, Kexi Zhu, Ming Lidoi:10.1016/j.jmps.2024.105752 通过空间选择性曝光实现无皱薄膜The extreme flexibility-induced wrinkling significantly hampers the promising engineering applications of membranes, while the existing wrinkling-suppression approaches have challenges for area loss, weight increase and interfacial delamination. Here we propose a facile wrinkle-free technique that enables stiffness modulation through spatioselective ultraviolet (UV) exposure, regulates stress distribution to eliminate compressive stresses and achieves robust wrinkle-free membranes. A small-deformation theoretical model with the Marguerre function is implemented to evaluate the wrinkling capability of a stiffness-modulated membrane, the non-gradient particle swarm optimization (PSO) algorithm is performed to obtain the optimal material distribution, and the related robust wrinkle-free performance is verified through both finite-deformation post-buckling analyses and physical experiments. In addition, an empirical wrinkle-free solution is also given without the requirement of excessive optimization. This wrinkle-free approach, with neither area loss, weight increase nor interfacial delamination, provides useful guidance for the research on wrinkle-free membranes.由极端柔性引起的皱纹严重阻碍了膜的工程应用前景，而现有的皱纹抑制方法又面临着面积损失、重量增加和界面分层的挑战。在这里，我们提出了一种简便的无皱技术，通过空间选择性紫外线（UV）照射实现刚度调节，调节应力分布以消除压应力，从而实现坚固的无皱膜。该研究利用马盖尔函数的小变形理论模型来评估刚度调制膜的起皱能力，并采用非梯度粒子群优化（PSO）算法来获得最佳材料分布，通过有限变形后屈曲分析和物理实验来验证相关的稳健无皱性能。此外，还给出了无需过度优化的经验无皱解决方案。这种无皱方法既不会造成面积损失、重量增加，也不会造成界面分层，为无皱膜的研究提供了有益的指导。Mechanics of MaterialsA mechanistic interpretation of Nelson curves for PVP failures under high temperature hydrogen attackDong Han, Yanfei Gao, Phillip E. Loya, Michael Swindeman, Jorge Penso, Zhili Fengdoi:10.1016/j.mechmat.2024.105079高温氢气侵蚀下 PVP 失效的纳尔逊曲线机理解析As an empirically established design criterion, Nelson curves that relate the service temperature and the allowable hydrogen partial pressure have been developed and utilized for more than sixty years in pressure vessels and piping (PVP) safety design. Despite a relatively clear thermodynamic understanding of the high-temperature-hydrogen-attack (HTHA) problem, the detailed fracture process on the microstructural length scales, however, remains elusive, and a quantitative assessment of the PVP lifetime under HTHA from the available creep fracture dataset is still not possible. This work develops a microstructure-informed and micromechanics-based model by incorporating a synergy between hydrogen transport and intergranular-cavity-based fracture process. Based on the available creep lifetime data of C-0.5Mo steels, we are able to calibrate material constitutive parameters, and then conduct nonlinear finite element simulations that reveal a real-time stress-induced hydrogen diffusional transport along grain boundaries, coupled with a microstructure-explicit failure process, from which Nelson curves can be computed. Such failure analyses allow us to delineate two distinct regimes on the Nelson curves, i.e., dislocation-creep-controlled or grain boundary diffusion-assisted cavity growth. More importantly, we found that a small change of the pipe thickness and applied stresses can significantly shift these lifetime curves. However, these two parameters are usually not provided in Nelson curves, thus limiting their usage in material selection and safety design. This discrepancy can clearly be mitigated by extensive parametric studies from our micromechanical modeling/simulation framework.纳尔逊曲线是根据经验确定的设计标准，它将使用温度和允许的氢分压联系起来，在压力容器和管道 (PVP) 安全设计中已经开发和使用了六十多年。尽管对高温氢气侵蚀（HTHA）问题有了相对清晰的热力学认识，但微观结构长度尺度上的详细断裂过程仍然难以捉摸，而且仍然无法根据现有的蠕变断裂数据集对高温氢气侵蚀下的 PVP 寿命进行定量评估。本研究结合氢传输和基于晶间空腔的断裂过程之间的协同作用，建立了一个基于微观结构和微观力学的模型。根据现有的 C-0.5Mo 钢蠕变寿命数据，我们能够校准材料构成参数，然后进行非线性有限元模拟，以揭示沿晶界的实时应力诱导氢扩散传输，并结合微观结构明确的失效过程，从而计算出纳尔逊曲线。通过这种失效分析，我们可以在纳尔逊曲线上划分出两种截然不同的状态，即位错-蠕变控制或晶界扩散辅助空穴生长。更重要的是，我们发现管材厚度和外加应力的微小变化都会显著改变这些寿命曲线。然而，纳尔逊曲线通常不提供这两个参数，因此限制了它们在材料选择和安全设计中的应用。通过我们的微机械建模/模拟框架进行广泛的参数研究，这种差异显然可以得到缓解。International Journal of PlasticityTime-resolved evolution of the deformation mechanisms in a TRIP/TWIP Fe50Mn30Co10Cr10 high entropy during tensile loading probed with synchrotron X-ray diffractionJ.G. Lopes, J. Shen, E. Maawad, P. Agrawal, N. Schell, R.S. Mishra, J.P. Oliveiradoi:10.1016/j.ijplas.2024.104048 利用同步辐射 X 射线衍射探测 TRIP/TWIP Fe50Mn30Co10Cr10 高熵在拉伸加载过程中变形机制的时间分辨演变The present research focuses on analyzing the deformation mechanisms associated with tensile loading of the Fe50Mn30Co10Cr10 high entropy alloy (HEA) using synchrotron x-ray diffraction (SXRD). This novel material is comprised by two major phases: γ-FCC and ε-HCP, where transformation induced plasticity (TRIP) effectively transforms the first into the latter, upon the application of an external stress. However, the presence of thermally stable ε-HCP prior to loading will also influence the deformation mechanism of the material during mechanical solicitation. As such, here we investigate the activation of different strain accommodation mechanisms and the consequent microstructural evolution. Four stages were identified in the mechanical response of this novel HEA, where the TRIP and the twinning induced plasticity (TWIP) deformation modes are the main events granting this HEA its outstanding properties. Such sequence of events allows to evidence the effectiveness of the collaboration between the transformative capability of the γ-FCC phase and the work hardening potential of the ε-HCP phase. This analysis is performed via quantitative and qualitative analysis of the SXRD data, allowing also to investigate the response behavior of specific crystallographic planes to the increasing stress throughout the experiment.本研究的重点是利用同步辐射 X 射线衍射 (SXRD) 分析与 Fe50Mn30Co10Cr10 高熵合金 (HEA) 拉伸负载相关的变形机制。这种新型材料由两个主要相组成：γ-FCC 和 ε-HCP，在施加外部应力时，转化诱导塑性（TRIP）可有效地将前者转化为后者。然而，加载前存在热稳定的 ε-HCP 也会影响材料在机械激励过程中的变形机制。因此，我们在此研究了不同应变容纳机制的激活以及随之而来的微结构演变。在这种新型 HEA 的机械响应中发现了四个阶段，其中 TRIP 和孪生诱导塑性（TWIP）变形模式是赋予这种 HEA 杰出性能的主要事件。这一系列事件证明了γ-FCC 相的转化能力与ε-HCP 相的加工硬化潜力之间的协同效应。这种分析是通过对 SXRD 数据进行定量和定性分析来完成的，同时还可以研究特定晶面在整个实验过程中对应力增加的响应行为。Thin-Walled StructuresAn advanced design diagram of stiffened plate subjected to combined in-plane and lateral loads considering initial deflection effectsZhuo Wang, Xiangshao Kong, Weiguo Wu, Do Kyun Kimdoi:10.1016/j.tws.2024.112144 考虑初始挠度效应的平面和侧向联合载荷加劲板高级设计图This study presents an advanced methodology for stiffened plates subjected to combined in-plane longitudinal compression and lateral loads. The proposed methodology is based on comprehensive numerical parametric analyses, and it utilises newly developed design curves for the lateral pressure limit and tailored empirical formulae for stiffened plates to increase the precision of ship structural designs. Plate–stiffener combination (PSC) members are used for the limit state analysis, which introduces various positions and initial deflection shapes specific to the PSC models. Local buckling-shaped deflections of the stiffener web are also incorporated into the analysis, which closely mirrors the real-world welding conditions of stiffened plates and provides deeper insight into their load-bearing capacities. These findings highlight the importance of accurately selecting the positions and initial deflections of stiffeners in PSC-based analyses to ensure that structural predictions are safe and reliable. The proposed method is grounded in conservative PSC models and represents a significant advancement in ship structural design in terms of safety and practicality.本研究针对承受平面纵向压缩和横向荷载的加劲板提出了一种先进的方法。所提出的方法基于全面的数值参数分析，并利用新开发的横向压力极限设计曲线和为加劲板量身定制的经验公式来提高船舶结构设计的精度。极限状态分析使用了板-加劲板组合（PSC）构件，引入了 PSC 模型特有的各种位置和初始挠度形状。加劲板腹板的局部屈曲形挠度也被纳入分析中，这密切反映了加劲板的实际焊接条件，并提供了对其承载能力的更深入了解。这些发现强调了在基于 PSC 的分析中准确选择加劲板位置和初始挠度的重要性，以确保结构预测安全可靠。所提出的方法以保守的 PSC 模型为基础，在安全性和实用性方面代表了船舶结构设计的重大进步。来源：复合材料力学仿真Composites FEM