Journal of The Mechanics and Physics of Solids最新文献_第6页

Eulerian rates of elastic incompatibilities applied to size-dependent hardening in finite torsion 弹性不相容的欧拉速率应用于有限扭转中的尺寸相关硬化

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-10-11 DOI: 10.1016/j.jmps.2024.105905

M.B. Rubin , Lorenzo Bardella

Measures of rates of elastic incompatibilities are developed within an Eulerian framework for finite-deformation response of anisotropic elastic–inelastic materials. Such framework relies on the evolution of microstructural vectors. It is emphasized that the rates of incompatibilities, here denoted as

R_{i j}

, depend on the constitutive equation for the rate of inelasticity. For small strains and rotations,

R_{i j}

are equal to the negative of the components of the rate of Nye-Kröner’s dislocation density tensor. In contrast to these small strain components, each

R_{i j}

is invariant under superposed rigid body motions such that it can be used independently in the constitutive equations to describe the material behavior. Specifically, in this work,

R_{i j}

provide a size-dependent enhancement to hardening that can increase or decrease during loading history, modeling the generation and annihilation of densities of geometrically necessary dislocations in metal plasticity. The application to the finite-deformation cyclic torsion of thin wires demonstrates the potential of this approach and the importance of the constitutive equation for the plastic spin rate both on the rotations of the microstructural vectors and on the predicted size-effect.

在各向异性弹性-非弹性材料有限变形响应的欧拉框架内开发了弹性不相容率的测量方法。这种框架依赖于微结构矢量的演变。需要强调的是，不相容率（此处表示为 Rij）取决于非弹性率的构成方程。对于小应变和旋转，Rij 等于 Nye-Kröner 位错密度张量速率分量的负值。与这些小应变分量不同的是，每个 Rij 在叠加刚体运动下都是不变的，因此可以在构成方程中独立使用，以描述材料行为。具体来说，在这项工作中，Rij 提供了与尺寸相关的硬化增强，在加载过程中可以增加或减少，从而模拟了金属塑性中几何必要位错密度的产生和湮灭。对细线有限变形循环扭转的应用证明了这种方法的潜力，以及塑性旋转率构成方程对微结构矢量旋转和预测尺寸效应的重要性。

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引用次数: 0

Progressive failure analysis of laminates with an open hole subjected to compressive loading (OHC) using the enhanced semi-discrete modeling framework 利用增强型半离散建模框架对承受压缩载荷（OHC）的开孔层压板进行渐进破坏分析

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-10-10 DOI: 10.1016/j.jmps.2024.105902

Vignesh Shankar Iyer, Minh Hoang Nguyen, Royan J. D’Mello, Anthony M. Waas

The Open-hole compressive (OHC) strength of a fiber reinforced laminate is one of the most critical allowables for design of aerostructures. In this paper, results for predicting the OHC strength using the semi-discrete damage modeling framework are presented. The predictions are seen to capture experimentally observed failure mechanisms and measured failure loads. The constitutive model includes local axial compressive failure (and subsequent load bearing at a reduced plateau stress) while maintaining numerical robustness. Standard stacking sequences (quasi-isotropic, “hard” and “soft”) have been analyzed and compared to publicly available databases. Additionally, the model is challenged to predict delamination-dominated failure due to ply-scaling. Overall, the model is able to capture relevant failure mechanisms, while the ultimate loads are predicted with good accuracy. Therefore, this framework can be used with confidence in predicting OHC strengths of laminates.

纤维增强层压板的开孔抗压强度（OHC）是航空结构设计中最关键的允许值之一。本文介绍了使用半离散损伤建模框架预测开孔抗压强度的结果。预测结果反映了实验观察到的破坏机制和测量到的破坏载荷。构成模型包括局部轴向压缩破坏（以及随后在降低的高原应力下的承载），同时保持了数值稳健性。对标准堆积序列（准各向异性、"硬 "和 "软"）进行了分析，并与公开数据库进行了比较。此外，该模型在预测由于层缩放造成的以分层为主的失效方面也面临挑战。总体而言，该模型能够捕捉到相关的失效机理，同时对极限载荷的预测也非常准确。因此，该框架可用于预测层压板的 OHC 强度。

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引用次数: 0

Crystallographically programmed kirigami metamaterials 晶体编程叽里呱啦超材料

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-10-10 DOI: 10.1016/j.jmps.2024.105903

Ruoqi He , Yao Chen , Jingbing Liang , Yue Sun , Jian Feng , Pooya Sareh

In recent years, lattice kirigami metamaterials have attracted considerable attention due to their unconventional and often intriguing mechanical properties. However, the absence of a comprehensive analytical framework has hindered advancements in both research and practical applications. Here, we introduce an integrated framework that enables the customization, form-finding, analysis, and manufacturing of polygonal lattice kirigami metamaterials (PLKMs). By employing a strain-energy-based method, we derive the effective mechanical properties of these systems and demonstrate that structural design is an effective strategy for tailoring these properties. Additionally, we introduce a group-theory-based method for generating crystallographic kirigami metamaterials through selective symmetry breaking, complemented by lattice theory to capture and program their structural characteristics. An automated workflow is also developed for modeling, analysis, and manufacturing of these metamaterials, followed by an image-processing-based design algorithm for composite PLKMs. To illustrate the capabilities of the proposed integrated framework, we explore its potential in driving innovative applications for PLKMs. It is anticipated that this work will provide valuable insights into potential innovations in kirigami metamaterial research and engineering.

近年来，晶格叽里咕噜超材料因其非传统且往往引人入胜的机械特性而备受关注。然而，由于缺乏全面的分析框架，阻碍了研究和实际应用的进展。在这里，我们介绍了一个综合框架，它可以实现多边形晶格叽里咕噜超材料（PLKMs）的定制、形状搜索、分析和制造。通过采用基于应变能的方法，我们得出了这些系统的有效力学性能，并证明结构设计是定制这些性能的有效策略。此外，我们还介绍了一种基于群论的方法，通过选择性对称破缺生成晶体学叽里呱啦超材料，并辅以晶格理论捕捉和编程其结构特征。此外，还为这些超材料的建模、分析和制造开发了一个自动化工作流程，随后又为复合 PLKM 开发了一种基于图像处理的设计算法。为了说明所提议的集成框架的能力，我们探讨了它在推动 PLKM 创新应用方面的潜力。预计这项工作将为叽里咕噜超材料研究和工程领域的潜在创新提供有价值的见解。

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引用次数: 0

Filled elastomers sliding over smooth obstacles: Experiments and modeling in large deformations 填充弹性体在光滑障碍物上滑动：大变形实验与建模

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-10-10 DOI: 10.1016/j.jmps.2024.105899

M. de Lorenzo , P. Le Tallec , O. Lopez-Pamies , P. Bussetta

The objective of this paper is to shed light on the mechanical response of filled elastomers in sliding contact. Compared to situations encountered by tires in breaking conditions, the study only considers smooth obstacles in order to analyze the contribution of finite deformations and of the complex viscosity of filled elastomers without facing all the complexity of surface roughness. For this purpose, a new experiment is introduced that allows to measure the friction on the surface of a filled elastomer that is subjected to large local deformation through a cyclic contact loading applied by sliding indenters. The setup uses smooth spherical indenters sliding on the material of interest within a temperature controlled water tank. The relevance of adhesion forces is reduced by using Teflon as a dry lubricant and Sinnozon as a surfactant. To analyze the experimental results, full-field simulations of the experiments are carried out within the setting of finite viscoelastodynamics by making use of two types of viscoelastic constitutive models for the filled elastomer: (

i

) a classical viscoelastic model combining a Mooney–Rivlin equilibrium elasticity and Maxwell branches with constant viscosities and (

i i

) an internal-variable-based viscoelastic model that was introduced in Kumar and Lopez-Pamies (2016) for unfilled elastomers and that is extended herein to account for the more complex viscous response of filled elastomers.

本文旨在阐明填充弹性体在滑动接触中的机械响应。与轮胎在破损条件下遇到的情况相比，本研究只考虑了光滑的障碍物，以便分析填充弹性体的有限变形和复杂粘度的贡献，而无需面对表面粗糙度的所有复杂性。为此，我们引入了一种新的实验，通过滑动压头施加循环接触载荷，测量局部变形较大的填充弹性体表面的摩擦力。该装置使用光滑的球形压头在温控水箱中的相关材料上滑动。使用聚四氟乙烯作为干润滑剂和 Sinnozon 作为表面活性剂可降低粘附力的相关性。为了分析实验结果，利用填充弹性体的两种粘弹性构成模型，在有限粘弹性动力学环境下对实验进行了全场模拟：(i) 经典粘弹性模型，结合了穆尼-里夫林平衡弹性和具有恒定粘度的麦克斯韦分支；(ii) 基于内部变量的粘弹性模型，该模型是 Kumar 和 Lopez-Pamies（2016 年）针对未填充弹性体推出的，在此进行了扩展，以考虑填充弹性体更为复杂的粘滞响应。

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引用次数: 0

Residual stress development in lattice mismatched epitaxial thin films via atomic and molecular layer depositions 通过原子层和分子层沉积实现晶格错配外延薄膜的残余应力发展

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-10-10 DOI: 10.1016/j.jmps.2024.105897

Musanna Galib , Okan K. Orhan , Jian Liu , Mauricio Ponga

Atomic and molecular layer deposition (ALD/MLD) coatings are promising solutions for preventing dendrite formation in aqueous and non-aqueous Li/Na/Zn metal batteries. Notably, alumina and alucone coatings have emerged as highly effective against dendrite formation in Zn anodes. Despite their demonstrated efficacy, a comprehensive understanding of their chemo-mechanical impact on anodes remains elusive. In this study, we take a bottom-up framework to these coatings on Zn foils, employing an approach that integrates ab initio simulations with continuum theories to elucidate lattice misfit and chemical bonding. We use this insight to develop a macroscopic model to predict the epitaxial residual stresses generated during thin-film deposition. Our findings reveal a robust chemical bonding between the hydroxylated Zn surface and the thin film. This, in turn, generates large misfit strains that result in significant interfacial stresses during deposition. These results are then compared to experiments by measuring the curvature of the coated thin films, finding good agreement between experiments and theory. This novel understanding sheds light on the fundamental mechanisms underpinning the development of chemo-mechanical stresses in thin films, which impact dendrite suppression in anodes, offering valuable insights for the design of new coatings.

原子层沉积和分子层沉积（ALD/MLD）涂层是防止水性和非水性锂/镍/锌金属电池形成枝晶的有效解决方案。值得注意的是，氧化铝和铝酮涂层对防止锌阳极中枝晶的形成非常有效。尽管它们的功效已得到证实，但对它们对阳极的化学机械影响的全面了解仍是空白。在本研究中，我们采用一种自下而上的框架来研究锌箔上的这些涂层，并采用一种将 ab initio 模拟与连续理论相结合的方法来阐明晶格错配和化学键。我们利用这一洞察力建立了一个宏观模型来预测薄膜沉积过程中产生的外延残余应力。我们的研究结果表明，羟基化 Zn 表面与薄膜之间存在强大的化学键。这反过来又会产生较大的错配应变，从而在沉积过程中产生显著的界面应力。然后，通过测量镀膜薄膜的曲率，将这些结果与实验进行比较，发现实验与理论之间存在良好的一致性。这种新颖的理解揭示了薄膜中化学机械应力发展的基本机制，这种应力会影响阳极中枝晶的抑制，从而为新型涂层的设计提供了宝贵的见解。

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引用次数: 0

Relation of synthesis and fatigue property in elastic soft materials 弹性软材料的合成与疲劳特性的关系

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-10-09 DOI: 10.1016/j.jmps.2024.105894

Yecheng Wang , Danqi Sun

Fatigue has long been studied for many materials, but many aspects are not well understood. Our recent study of the distinct roles of crosslinks and entanglements in the synthesis-property relation of a polymer network under monotonic load leads to a fundamental question: how do crosslinks and entanglements affect the synthesis-property relation of a polymer network under cyclic load? Here we study the relation of synthesis and fatigue property of elastic soft materials without precut cracks. We prepare polyacrylamide hydrogels by free radical polymerization as a model system, and swell the hydrogels in water to equilibrium or to a certain amount of polymer content. The synthesis parameters include the crosslinker-to-monomer molar ratio and the water-to-monomer molar ratio in the precursor, as well as the polymer content in the hydrogel. Three series of hydrogels are prepared. For each hydrogel, the stress-stretch curve under cyclic stretch of various amplitudes and the number of cycles to rupture are measured, giving four properties: fatigue life, endurance stretch, endurance stress, and endurance work. When the crosslinker-to-monomer molar ratio in the precursor is high, the degree of network imperfection on average is low. When the water-to-monomer molar ratio in the precursor is low, the number of entanglements per polymer segment on average is large. We show that crosslinks decrease the susceptibility to fatigue and entanglements increase the endurance stress. By contrast, both crosslinks and entanglements negligibly affect the endurance stretch and the endurance work.

长期以来，人们一直在研究许多材料的疲劳问题，但对许多方面还不甚了解。我们最近对交联和缠结在单调载荷下聚合物网络的合成-性能关系中的不同作用进行了研究，从而提出了一个基本问题：交联和缠结如何影响循环载荷下聚合物网络的合成-性能关系？在此，我们研究了无预切裂纹的弹性软材料的合成与疲劳特性之间的关系。我们以自由基聚合法制备聚丙烯酰胺水凝胶为模型体系，将水凝胶在水中溶胀至平衡或一定量的聚合物含量。合成参数包括前体中交联剂与单体的摩尔比、水与单体的摩尔比以及水凝胶中的聚合物含量。共制备了三个系列的水凝胶。对于每种水凝胶，都测量了在不同幅度的循环拉伸下的应力-拉伸曲线以及破裂的循环次数，从而得出四种特性：疲劳寿命、耐久拉伸、耐久应力和耐久功。当前驱体中交联剂与单体的摩尔比高时，网络不完善程度平均较低。前体中水与单体的摩尔比低时，平均每个聚合物段的缠结数量大。我们的研究表明，交联会降低疲劳敏感性，而缠结则会增加耐久应力。相比之下，交联和缠结对耐久拉伸和耐久功的影响微乎其微。

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引用次数: 0

A mechanics-based data-free Problem Independent Machine Learning (PIML) model for large-scale structural analysis and design optimization 基于力学的无数据问题独立机器学习（PIML）模型，用于大规模结构分析和设计优化

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-10-09 DOI: 10.1016/j.jmps.2024.105893

Mengcheng Huang , Chang Liu , Yilin Guo , Linfeng Zhang , Zongliang Du , Xu Guo

Machine learning (ML) enhanced fast structural analysis and design recently attracted considerable attention. In most related works, however, the generalization ability of the ML model and the massive cost of dataset generation are the two most criticized aspects. This work combines the advantages of the universality of the substructure method and the superior predictive ability of the operator learning architecture. Specifically, using a novel mechanics-based loss function, lightweight neural network mapping from the material distribution inside a substructure and the corresponding continuous multiscale shape function is well-trained without preparing a dataset. In this manner, a problem machine learning model (PIML) that is generally applicable for efficient linear elastic analysis and design optimization of large-scale structures with arbitrary size and various boundary conditions is proposed. Several examples validate the effectiveness of the present work on efficiency improvement and different kinds of optimization problems. This PIML model-based design and optimization framework can be extended to large-scale multiphysics problems.

机器学习（ML）增强型快速结构分析与设计最近引起了广泛关注。然而，在大多数相关工作中，ML 模型的泛化能力和数据集生成的巨大成本是最受诟病的两个方面。这项工作结合了子结构方法的通用性和算子学习架构的卓越预测能力这两个优势。具体来说，利用一种新颖的基于力学的损失函数，可以在不准备数据集的情况下，很好地训练轻量级神经网络映射，即下部结构内部的材料分布和相应的连续多尺度形状函数。通过这种方式，我们提出了一种问题机器学习模型（PIML），它普遍适用于任意尺寸和各种边界条件的大型结构的高效线性弹性分析和设计优化。多个实例验证了本研究在提高效率和解决各类优化问题方面的有效性。这种基于 PIML 模型的设计和优化框架可扩展到大型多物理场问题。

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引用次数: 0

Effective thermodynamic potentials and internal variables: Particulate thermoviscoelastic composites 有效热力学势和内部变量：微粒热塑复合材料

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-10-08 DOI: 10.1016/j.jmps.2024.105891

Noël Lahellec , Renaud Masson , Pierre Suquet

The problem addressed in this study is the full coupling between three different contributions to the strain in thermoviscoelastic composites, elasticity, viscosity and temperature changes. It shows that even in simple situations, the coupling with temperature may lead to counter-intuitive effects which are not accounted for through the sole overall stress–strain relations. The correspondence principle permits to express the macroscopic strain–stress relation and the macroscopic entropy as a set of ordinary differential equations for two types of effective internal variables, mechanical variables on the one hand and thermal variables on the other hand. Interpreting the macroscopic response as a rheological generalized Maxwell model allows us to compute the macroscopic free energy and the dissipated energy of the composite in terms of these internal variables. Coupled with Hashin–Shtrikman estimates, these thermodynamic functions provide additional information on the statistics of the stress field when the composite is subjected to a mixed loading combining mechanical and thermal effects.

本研究解决的问题是热粘弹性复合材料应变的三种不同贡献（弹性、粘度和温度变化）之间的全面耦合。研究表明，即使在简单的情况下，与温度的耦合也可能导致反直觉效应，而这种效应并不能通过单一的整体应力应变关系加以解释。对应原理允许将宏观应变-应力关系和宏观熵表示为两类有效内部变量的常微分方程组，一类是机械变量，另一类是热变量。将宏观响应解释为流变学广义麦克斯韦模型，我们就能根据这些内部变量计算出复合材料的宏观自由能和耗散能。这些热力学函数与 Hashin-Shtrikman 估计值相结合，为复合材料在承受机械和热效应混合加载时的应力场统计提供了更多信息。

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引用次数: 0

Crack tip stress intensification in strain-induced crystallized elastomer 应变诱导结晶弹性体的裂纹尖端应力强化

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-10-05 DOI: 10.1016/j.jmps.2024.105895

Thanh-Tam Mai , Katsuhiko Tsunoda , Kenji Urayama

Natural rubber (NR) exhibits strain-induced crystallization (SIC), enhancing tearing strength and crack resistance. However, the reinforcement mechanism along with nonuniform strain around a crack tip remains unclear. We reveal the nonuniform stress field around a crack tip using the DIC-based deformation field data and a hyperelasticity approach. A hyperelastic strain energy density function (W) is derived to be able to replicate stress-strain data across various deformations, encompassing equal and unequal biaxial, uniaxial, and pure shear stretching. These data cover the full range and magnitude of deformations around the crack tip. SIC significantly impacts the singular behaviors of strain and stress near the crack tip, causing a pronounced stress increase and strain decrease within the SIC zone that extends up to approximately 100 μm away from the crack tip. This results in a distinct crossover in singularity power-law index between the SIC zone and the fully amorphous zone. With increasing crack opening, the stress upturn intensifies, and the crossover shifts away from the crack tip due to SIC zone enlargement and local crystallinity increase. These findings deepen our understanding of the physics of SIC near crack tips and its reinforcement mechanism in strain-induced crystallizable soft solid materials.

天然橡胶（NR）具有应变诱导结晶（SIC）特性，可提高撕裂强度和抗裂性。然而，裂纹尖端周围的非均匀应变的强化机制仍不清楚。我们利用基于 DIC 的变形场数据和超弹性方法揭示了裂纹尖端周围的非均匀应力场。超弹性应变能量密度函数（W）可用于复制各种变形的应力应变数据，包括等量和不等量双轴、单轴和纯剪切拉伸。这些数据涵盖了裂纹尖端周围的全部变形范围和幅度。SIC 极大地影响了裂纹尖端附近应变和应力的奇异行为，导致 SIC 区域内应力明显增加，应变明显减小，该区域延伸至裂纹尖端约 100 μm 处。这导致在 SIC 区和全非晶区之间出现明显的奇异幂律指数交叉。随着裂纹开口的增大，应力上行加剧，由于 SIC 区扩大和局部结晶度增加，交叉点远离裂纹尖端。这些发现加深了我们对裂纹尖端附近 SIC 的物理特性及其在应变诱导可结晶软固体材料中的强化机制的理解。

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引用次数: 0

Investigating fracture mechanisms in glassy polymers using coupled particle-continuum simulations 利用粒子-连续介质耦合模拟研究玻璃态聚合物的断裂机制

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-10-05 DOI: 10.1016/j.jmps.2024.105884

Wuyang Zhao , Yash Jain , Florian Müller-Plathe , Paul Steinmann , Sebastian Pfaller

We study the fracture behavior of glassy polymers using a multiscale simulation method that integrates a molecular dynamics (MD) system within a continuum domain. By employing a nonlinear viscoelastic constitutive model in the continuum domain, the MD system undergoes non-uniform deformation with flexible boundaries through interaction with the surrounding continuum. Systems with pre-defined double cracks are subjected to tensile stretch under various geometric constraints and bond breakage criteria. The simulation results show that geometric constraints primarily affect deformation behavior at small strains, but their influence diminishes at larger strains. In the stage of fracture, increased deformation correlates with a narrowing distribution of microscopic structures at molecular scales, such as bond length. This distribution converges across different systems just before fracture, irrespective of ultimate stress, fracture strain, bond breakage criteria, and geometric constraints. This convergence suggests that the distribution of microscopic structures is a fundamental property linked to the fracture behavior of glassy polymers.

我们采用多尺度模拟方法研究了玻璃态聚合物的断裂行为，该方法将分子动力学（MD）系统集成在连续域中。通过在连续域中采用非线性粘弹性构成模型，MD 系统在与周围连续体的相互作用下发生具有柔性边界的非均匀变形。带有预定义双裂缝的系统在各种几何约束和粘接断裂标准下受到拉伸。模拟结果表明，几何约束主要影响小应变时的变形行为，但其影响在较大应变时会减弱。在断裂阶段，变形的增加与微观结构在分子尺度（如键长）上的分布变窄有关。无论极限应力、断裂应变、键断裂标准和几何约束如何，这种分布在不同体系中都会在断裂前趋于一致。这种趋同性表明，微观结构的分布是与玻璃态聚合物断裂行为相关的基本特性。

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引用次数: 0