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 3 篇
Wrinkling–dewrinkling transitions in stretched soft spherical shells
Yu-Kun Hao, Bo Li, Xi-Qiao Feng, Huajian Gao
doi:10.1016/j.ijsolstr.2024.112773
拉伸软球壳中的起皱-脱皱转变
Soft shells undergoing intricate buckling and morphological evolutions can serve as a model system for understanding the morphogenesis of organs, tissues, cells, and nuclei. In this paper, we combine experiments, simulations, and theoretical analysis to investigate the wrinkling and subsequent morphological transitions in a soft spherical shell subjected to an outward concentrated force. During loading, the spherical shell first buckles into many shallow radial wrinkles, which soon merge into a single crater-like deep wrinkle, and then the number of wrinkles increases with loading. Surprisingly, after a critical point, all wrinkles disappear and the shell regains an axisymmetric, smooth shape, referred to as dewrinkling. We show how this anomalous wrinkling–dewrinkling transition stems from the interplay between surface curvature and large deformations. Material-independent scaling laws are established from an energy analysis to predict the surface wrinkling pattern, which depends on the loading force. This work provides physical insights into how local forces can regulate the shape evolutions of soft shells, which can take place in, for example, the morphogenesis of developing organisms.
经历复杂屈曲和形态演变的软壳可以作为理解器官、组织、细胞和细胞核形态发生的模型系统。在本文中,我们结合实验、模拟和理论分析,研究了软球壳在向外集中力作用下的起皱和随后的形态转变。在加载过程中,球壳首先屈曲成许多浅径向皱纹,这些皱纹很快合并成一个火山口状的深皱纹,然后皱纹的数量随着加载而增加。令人惊讶的是,在一个临界点之后,所有皱纹都消失了,壳体恢复了轴对称的光滑形状,这就是所谓的 "脱皱"。我们展示了这种反常的起皱-脱皱过渡如何源于表面曲率和大变形之间的相互作用。我们通过能量分析建立了与材料无关的缩放定律,以预测取决于加载力的表面起皱模式。这项工作提供了关于局部力如何调节软壳形状演变的物理见解,这种演变可能发生在例如发育中生物的形态发生过程中。
Co-rotational 3D beam element using quaternion algebra to account for large rotations: Formulation theory and static applications
Stéphane Grange, David Bertrand
doi:10.1016/j.ijsolstr.2024.112746
使用四元代数计算大旋转的共旋转三维梁元素:公式理论与静态应用
This paper presents a co-rotational beam element based on quaternion algebra as a means of parameterizing large rotations. This co-rotational framework is based on a decomposition of beam kinematics into a rigid element frame, which follows the element and its pure deformation. Once the decomposition between rigid body motion and deformation is obtained, the principle of virtual work allows calculating the element response projected onto large displacements and rotations. This 3D co-rotational element lies within the framework of incremental formulations. The special feature of this formulation pertains to the decomposition of kinematics to extract the rigid body motion and pure deformations through use of quaternion algebra by solving an internal nonlinear kinematic equation. Thus, from the 2 quaternions defining global rotations and the 2 displacement vectors at the ends of the beam, this method is able to extract: 1 quaternion and 1 displacement vector parameterizing the rigid body motion, plus 2 other quaternions defining the internal rotations and beam elongation. The proposed formulation based on quaternion algebra therefore constitutes an alternative to the literature’s treatment of large-rotation kinematics using a quaternion algebra. The operators are also linearized in order to obtain the algorithmic stiffness operator. Eleven distinct static numerical applications are presented, along with comparisons from the literature in the aim of demonstrating the efficiency of this proposed element.
本文提出了一种基于四元数代数的共旋转梁元素,作为大旋转参数化的一种手段。这种共旋转框架基于将梁运动学分解为刚体元素框架,该框架遵循元素及其纯变形。一旦获得了刚体运动和变形之间的分解,就可以利用虚功原理计算投射到大位移和大旋转上的元素响应。这种三维同向旋转元素属于增量公式的范畴。这种计算方法的特点在于通过求解内部非线性运动方程,使用四元代数对运动学进行分解,从而提取刚体运动和纯变形。因此,从定义全局旋转的 2 个四元数和横梁两端的 2 个位移矢量中,该方法能够提取:1 个四元数和 1 个位移矢量参数化刚体运动,以及定义内部旋转和横梁伸长的另外 2 个四元数。因此,基于四元数代数的拟议公式是文献中使用四元数代数处理大旋转运动学的一种替代方法。为了获得算法刚度算子,还对算子进行了线性化处理。本文介绍了 11 个不同的静态数值应用,并与文献进行了比较,旨在证明这种拟议元素的效率。
Computational multiscale modelling of material interfaces in electrical conductors
Tobias Kaiser, Niklas von der Höh, Andreas Menzel
doi:10.1016/j.jmps.2024.105601
电导体材料界面的多尺度计算建模
Material interfaces occur at various length scales and may exhibit significantly different properties than the surrounding bulk. Motivated by their importance for electrical engineering applications such as wire bonds and electrically conductive adhesives, the focus of the present work is on material interfaces in electrical conductors. In order to approximate the physical interphase (of finite thickness) as a (zero-thickness) cohesive zone-type interface in macroscale simulations, scale-bridging relations are established that relate the apparent electro-mechanical interface properties to the underlying microstructure. A finite element-based implementation is discussed with particular focus lying on the efficient calculation of the flux-type macroscale quantities and the associated generalised algorithmic consistent tangent stiffness tensors. Analytical solutions are derived for validation purposes and representative boundary value problems are studied.
材料界面出现在不同的长度尺度上,可能会表现出与周围体质明显不同的特性。由于材料界面在电线粘接和导电胶等电气工程应用中的重要性,本研究的重点是电导体中的材料界面。为了在宏观模拟中将物理相间(有限厚度)近似为(零厚度)内聚区型界面,建立了尺度桥接关系,将表面电气机械界面特性与底层微观结构联系起来。讨论了基于有限元的实现方法,重点是如何高效计算通量型宏观量和相关的通用算法一致切线刚度张量。为验证目的还推导了分析解,并研究了具有代表性的边界值问题。
Anisotropic evolution of viscous strain in soft biological materials
Jacopo Ciambella, Giulio Lucci, Paola Nardinocchi
doi:10.1016/j.mechmat.2024.104976
软生物材料中粘性应变的各向异性演变
We propose a model for anisotropic viscoelastic biological materials that can handle large deformations, based on the kinematic assumption that the reinforcing fibre structure undergoes affine deformation with the underlying matrix. A generalized orientation tensor approach is used to account for the dispersion of the fibres. Moreover, we consider a strain energy function that features both an elastic and an overstress component, corresponding to distinct natural states. As a consequence of this choice, the remodelled state is not necessarily stress-free, and the material does not completely relax the stress. Notably, we consider that viscous remodelling also alters the fibre distribution, leading to a dependence of the overstress energy on the remodelled orientation tensor. An anisotropic evolution equation for the viscous strain is then derived, which has five distinct characteristic times if a single fibre family is considered and requires no additional assumptions on the viscous spin. To implement the model, we prove that the evolution of the viscous strain can be recast in a variational form by an Onsager variational principle. Finally, we discuss the algorithm used for the simulations and show numerical examples that serve as benchmark test cases for viscoelastic materials.
我们提出了一种可处理大变形的各向异性粘弹性生物材料模型,该模型基于增强纤维结构与底层基质发生仿射变形的运动学假设。我们采用广义取向张量法来考虑纤维的分散性。此外,我们考虑的应变能函数具有弹性和过应力两个分量,与不同的自然状态相对应。由于这一选择,重塑状态不一定是无应力的,材料也不会完全放松应力。值得注意的是,我们认为粘性重塑也会改变纤维分布,从而导致过应力能量取决于重塑的取向张量。然后推导出粘性应变的各向异性演化方程,如果考虑单一纤维系列,该方程有五个不同的特征时间,并且不需要对粘性自旋进行额外假设。为了实现该模型,我们证明了粘性应变的演化可以通过昂萨格变分原理以变分形式进行重构。最后,我们讨论了用于模拟的算法,并展示了作为粘弹性材料基准测试案例的数值示例。
Temperature dependent deformation behavior and texture evolution in AA6082 aluminum alloy: An integrated experimental and crystal plasticity simulation approach
Oleksandr Lypchanskyi, Chen-Chun Chiu, Faisal Qayyum, Grzegorz Korpała, Sergey Guk, Ching-Kong Chao, Ulrich Prahl
doi:10.1016/j.ijplas.2024.103942
AA6082 铝合金随温度变化的变形行为和纹理演变:综合实验与晶体塑性模拟方法
This research provides a comprehensive analysis of the texture and temperature dependent deformation behavior of the aluminum alloy AA6082. The study is performed using a combination of experimental deformation tests and computational simulations based on a crystal plasticity (CP) framework. The primary objective is to identify the critical influence of temperature on local stress states and dislocation density within the material during tensile tests. From an experimental perspective, the study employs ex-situ deformation tests and subsequent electro backscatter diffraction (EBSD) data in combination with energy dispersive x-ray spectrometer (EDS) analysis at 200°C and 400°C. The experimental EBSD data are adopted, preprocessed and converted into a geometry file for the numerical simulations. On the computational front, a dislocation density-based material model is adopted for CP simulations. The physical and fitting parameters of the model are calculated, adopted from the literature, or calibrated by comparing the global simulation results with experimental stress-strain observations under uniaxial tensile load at room temperature, 200°C and 400°C. Empirical functions for solid solution strengthening, dislocation density, fitting parameters controlling mean free path and dislocation annihilation have been derived that can be used to quickly interpolate them for any intermediate temperature. These functions combined with other model parameters one can now be used for temperature-dependent CP modeling of AA6082. The isothermal grain-scale simulation and ex-situ experimental results confirmed a noteworthy texture transformation at higher temperatures, characterized by a reduction in the primary Cube orientation and its transition into a Copper orientation due to the stretching process. The correlation between the experimental results and the simulations on macro and micro scales is reasonable, indicating the accuracy and effectiveness of the CP approach in predicting the temperature dependent deformation behavior and texture evolution in aluminum alloys.
本研究对铝合金 AA6082 的质地和随温度变化的变形行为进行了全面分析。研究采用了实验变形测试和基于晶体塑性(CP)框架的计算模拟相结合的方法。主要目的是确定在拉伸试验过程中,温度对材料内部局部应力状态和位错密度的关键影响。从实验角度来看,该研究采用了 200°C 和 400°C 下的原位变形测试和随后的电子反向散射衍射(EBSD)数据,并结合能量色散 X 射线光谱仪(EDS)分析。EBSD 实验数据经过预处理并转换成几何文件,用于数值模拟。在计算方面,CP 模拟采用了基于位错密度的材料模型。模型的物理参数和拟合参数是通过计算、从文献中采用或将全局模拟结果与室温、200°C 和 400°C 单轴拉伸载荷下的实验应力应变观测结果进行比较而校准的。固溶强化、位错密度、控制平均自由路径和位错湮灭的拟合参数的经验函数已经得出,可用于在任何中间温度下快速插值。这些函数与其他模型参数相结合,现在可用于对 AA6082 进行随温度变化的 CP 建模。等温晶粒尺度模拟和现场实验结果证实,在较高温度下会出现值得注意的纹理转变,其特点是主立方取向减少,并在拉伸过程中转变为铜取向。实验结果与宏观和微观尺度上的模拟结果之间存在合理的相关性,表明 CP 方法在预测铝合金随温度变化的变形行为和纹理演变方面的准确性和有效性。
The large strain snap-through effect in free torsion of highly elastic soft thin-walled tubes with exact closed-form solutions
Hao-Nan He, Si-Yu Wang, Hui-Feng Xi, Heng Xiao, Lin Zhan, Jia-Shun Zhou
doi:10.1016/j.tws.2024.111803
高弹性软薄壁管自由扭转中的大应变快穿效应与精确闭式解
It is found for the first time that, as the applied torque attains a critical value, a freely twisted highly elastic tube may jump from one to another state over large strain range. Unlike usual approximate buckling analyses of thin shell structures with Hooke’s law for small strain, such large strain snap-through effect needs to be studied with a large strain model that can accurately simulate nonlinear elastic behaviors of soft materials. As such, nonlinear coupling issues have to be treated both in large strain kinematics and in hyper-elastic constitutive formulation. It appears that exact results would be rare even for buckling analyses with small strain but large deflections. Here, the above coupling issues are treated with a novel and decoupled approach. To this end, explicit and decoupled forms of the dual potentials for hyper-elastic stress–strain and strain-stress relationships are constructed with well-designed invariants of the Hencky strain and the deviatoric Cauchy stress and, hence, multiple data sets from benchmark tests are accurately matched with these forms in a decoupled sense. It is then shown that the nonlinear coupling equations for large torsion of elastic thin tubes can be worked out to produce exact closed-form solutions for the average radius ratio, the axial length ratio and the thickness ratio as well as the applied torque. With these solutions, the large strain snap-through effect is disclosed with an explicit criterion. Furthermore, numerical examples are provided with comparison to test data and, in particular, the large torsion response features with the snap-through effect are discussed with reference to possible correlations to certain symptoms in vascular abnormalities of blood vessels, etc.
研究首次发现,当施加的扭矩达到临界值时,自由扭转的高弹性管可能会在大应变范围内从一种状态跳转到另一种状态。与通常使用胡克定律对薄壳结构进行小应变近似屈曲分析不同,这种大应变跃穿效应需要使用能精确模拟软材料非线性弹性行为的大应变模型进行研究。因此,非线性耦合问题必须在大应变运动学和超弹性构成公式中加以处理。即使是应变小但挠度大的屈曲分析,似乎也很少能得到精确的结果。在此,我们采用一种新颖的解耦方法来处理上述耦合问题。为此,利用精心设计的亨茨基应变和偏离考奇应力的不变量,构建了超弹性应力-应变和应变-应力关系的显式解耦双势垒形式,从而在解耦意义上将基准测试的多个数据集与这些形式精确匹配。研究表明,通过计算弹性薄管大扭转的非线性耦合方程,可以得出平均半径比、轴向长度比和厚度比以及外加扭矩的精确闭式解。有了这些解法,大应变快穿效应就有了明确的标准。此外,还提供了与测试数据相比较的数值示例,特别是讨论了大扭转响应特征与快穿效应可能与血管异常的某些症状等的相关性。
Synergistically improving interface behavior by designing physical twisting structure and “rigid-flexible” interface layer on ultra-high molecular weight polyethylene (UHMWPE) fiber surface
Ziyu Zhao, Zhijia Dong, Chaoyu Chen, Jiajia Peng, Pibo Ma
doi:10.1016/j.tws.2024.111805
通过在超高分子量聚乙烯(UHMWPE)纤维表面设计物理扭曲结构和 "刚柔并济 "的界面层,协同改善界面行为
The application limitations of Ultra-high molecular weight polyethylene (UHMWPE) fiber reinforced composites in different fields can be attributed to their surface chemical inertness and weak interfacial adhesion. Herein, we developed a novel method for preparation of a stable biomimetic layer surface treatment, via the combination use of physical twisting structure and “rigid-flexible” interface layer. Unlike the conventional methods under special conditions, in this method, the UHMWPE fibers were converted into twisting structure, and the efficient nanoparticle deposition facilitated on the fiber surface in the presence of reductive dopamine coating. Moreover, the multi-structured synergy promotes the roughness of the T-UHMWPE fiber, which improves the interface bonding strength of the fibers-reinforced composites. The effectiveness of the modified treatment was evaluated by Fourier transform infrared spectroscopy (FT-IR), microscopic confocal laser Raman spectrometer (Raman), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), contact angle and surface free energy. The surface morphology and interfacial properties of the treatment was evaluated using field emission scanning electron microscopes (FE-SEM) and energy dispersive spectrometry (EDS). The experimental results demonstrated that the interfacial shear strength (IFSS) of the modified T-UHMWPE was improved by 218%, compared with those of the unmodified UHWMPE fibers. This innovative approach, combining physical twisting structure and “rigid-flexible” interface layer, would provide a valuable potential for the preparation of advanced UHMWPE reenforced composites with high interfacial bond strength.
超高分子量聚乙烯(UHMWPE)纤维增强复合材料在不同领域的应用局限性可归因于其表面化学惰性和弱界面粘附性。在此,我们开发了一种新方法,通过结合使用物理扭曲结构和 "刚柔相济 "的界面层,制备稳定的仿生物层表面处理。与特殊条件下的传统方法不同,在该方法中,超高分子量聚乙烯纤维被转化为扭曲结构,在还原性多巴胺涂层的作用下,促进了纳米粒子在纤维表面的高效沉积。此外,多结构协同作用促进了 T-UHMWPE 纤维的粗糙度,从而提高了纤维增强复合材料的界面结合强度。傅立叶变换红外光谱(FT-IR)、显微共焦激光拉曼光谱仪(Raman)、X 射线光电子能谱(XPS)、热重分析(TGA)、接触角和表面自由能对改性处理的效果进行了评估。使用场发射扫描电子显微镜(FE-SEM)和能量色散光谱仪(EDS)对处理的表面形貌和界面特性进行了评估。实验结果表明,与未经改性的超高分子量聚乙烯纤维相比,改性超高分子量聚乙烯纤维的界面剪切强度(IFSS)提高了 218%。这种结合了物理扭曲结构和 "刚柔相济 "界面层的创新方法将为制备具有高界面结合强度的先进超高分子量聚乙烯增强复合材料提供宝贵的潜力。
Multi-Body Dynamical Modeling and Prediction of Flexible Origami/Kirigami Structures by Affine Transformation
Fan Jiang, Xiuting Sun, Jian Xu
doi:10.1016/j.tws.2024.111802
通过仿射变换对柔性折纸/剪纸结构进行多体动力学建模和预测
A generalized multi-body dynamical modeling method of Origami/Kirigami structures considering the elastic-flexible coupling of surfaces and nonlinear creases is proposed. For different structures with complex spatial configuration and constraints, an Affine Transformation (AT) technique based on Absolute Nodal Coordinate Formulation (ANCF) is proposed to make the modeling more convenient and efficient. The surfaces are discretized by triangle reduced elements, and the constitutive relations of creases are described by nonlinear state-dependent torque constraints. The proof of the topological invariance of configurations is also given. The simulation of the folding capacity and dynamic behaviors on two Origami structures, Origami solar array mechanism, and enclosed Yoshimura Origami, are given, which verifies the effectiveness of the modeling method. Additionally, the quantitative dynamic behaviors contributes to the design principle of a Kirigami structure for multi-stability. Comparisons between theoretical results from modeling and experiments demonstrate the effectiveness of the modeling method and crease design. The AT-ANCF lays a theoretical foundation for dynamic prediction and design for large deformation Origami/ Kirigami structures, which has significant potential applications in dynamic properties design in the fields of aerospace, robotic etc.
考虑到曲面的弹性柔性耦合和非线性折痕,提出了折纸/剪纸结构的广义多体动力学建模方法。针对具有复杂空间构造和约束条件的不同结构,提出了一种基于绝对节点坐标形式(ANCF)的仿射变换(AT)技术,使建模更加方便和高效。表面由三角形简化元素离散化,折痕的构成关系由非线性状态相关扭矩约束描述。同时还给出了构型拓扑不变性的证明。给出了两种折纸结构--折纸太阳能阵列机构和封闭式吉村折纸--的折叠能力和动态行为仿真,验证了建模方法的有效性。此外,定量的动态行为还为多稳态叽里纸结构的设计原理做出了贡献。建模的理论结果与实验结果之间的比较证明了建模方法和折痕设计的有效性。AT-ANCF 为大变形折纸/剪纸结构的动态预测和设计奠定了理论基础,在航空航天、机器人等领域的动态特性设计中具有重要的潜在应用价值。