【新文速递】2024年2月11日固体力学SCI期刊最新文章

 

今日更新：International Journal of Solids and Structures 3 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 2 篇

International Journal of Solids and Structures

Semi-analytical solution to elastic–plastic contact-impact between a 316 stainless steel rod with truncated cone nose and rigid flat

Yifan Wang, Tao Wang, Xuan Ye

doi:10.1016/j.ijsolstr.2024.112702

带有截顶锥鼻的 316 不锈钢棒与刚性平面之间的弹塑性接触撞击的半解析解

When subjected to impacts, rods suffer local large deformation and global vibrational deformation along with abrupt kinematic and mechanical response changes. Studies on the responses during impact are beneficial to structural health monitoring. In this study, both kinds of deformation of rods with truncated-cone noses were investigated. A semi-analytical solution describing the vibrational responses of the rod was obtained based on the plastic contact model of the truncated-cone nose against a rigid flat and the one-dimension hypothesis of the rod. The theoretically predicted results agreed well with those calculated by finite element model (FEM), and the scaling law in rod response was theoretically derived and verified by FEM. Besides, the compression degree of the rod with three truncated-cone noses was considered, and the rod nose of lower contact stiffness presented better buffering effects. Finally, the applicability map of the semi-analytical solution was depicted according to the scope of the contact model.

在受到冲击时，杆件会发生局部大变形和整体振动变形，同时运动学和机械响应也会发生突变。对冲击过程中的响应进行研究有利于结构健康监测。在本研究中，对带有截顶锥形鼻的杆件的两种变形进行了研究。根据截顶锥鼻与刚性平面的塑性接触模型和杆的一维假设，得到了描述杆振动响应的半解析解。理论预测结果与有限元模型（FEM）计算结果吻合良好，理论上得出了杆件响应的缩放规律，并通过有限元模型得到了验证。此外，还考虑了具有三个截顶锥鼻的杆的压缩程度，发现接触刚度较低的杆鼻具有更好的缓冲效果。最后，根据接触模型的范围描绘了半解析解的适用图。

Revealing the unusual rate-dependent mechanical behaviors of nematic liquid crystal elastomers

Christopher Chung, Chaoqian Luo, Christopher M. Yakacki, Bo Song, Kevin Long, Kai Yu

doi:10.1016/j.ijsolstr.2024.112712

揭示向列液晶弹性体随速率变化的异常力学行为

Liquid crystal elastomers (LCEs) exhibit unique mechanical properties of soft elasticity and enhanced energy dissipation with rate dependency. They are potentially transformative materials for applications in mechanical impact mitigation and vibration isolation. However, previous studies have primarily focused on the mechanics of LCEs under equilibrium and quasistatic loading conditions. Critical knowledge gaps exist in understanding their rate-dependent behaviors, which are a complex mixture of traditional network viscoelasticity and the soft elastic behaviors with changes in the mesogen orientation and order parameter. Together, these inelastic mechanisms lead to unusual rate-dependent energy absorption responses of LCEs. In this work, we developed a viscoelastic constitutive theory for monodomain nematic LCEs to investigate how multiple underlying sources of inelasticity manifest in the rate-dependent and dissipative behaviors of monodomain LCEs. The theoretical modeling framework combines the neo-classical network theory with evolution rules for the mesogen orientation and order parameter with conventional viscoelasticity. The model is calibrated with uniaxial tension and compression data spanning six decades of strain rates. The established 3D constitutive model enables general loading predictions taking the initial mesogen orientation and order parameter as inputs. Additionally, parametric studies were performed to further understand the rate dependence of monodomain LCEs in relation to their energy absorption characteristics. Based on the parametric studies, particularly loading scenarios are identified as conditions where LCEs outperform conventional elastomers regarding energy absorption.

液晶弹性体（LCE）具有独特的软弹性机械特性和随速率变化而增强的能量耗散特性。液晶弹性体是一种潜在的变革性材料，可用于减轻机械冲击和隔离振动。然而，以往的研究主要集中于 LCE 在平衡和准静态加载条件下的力学特性。这些行为是传统网络粘弹性与介质取向和有序参数变化时的软弹性行为的复杂混合物。这些非弹性机制共同导致了 LCE 不同寻常的随速率变化的能量吸收响应。在这项研究中，我们开发了单体向列 LCE 的粘弹性构成理论，以研究多种潜在的非弹性来源如何在单体 LCE 的速率依赖性和耗散行为中表现出来。理论建模框架结合了新古典网络理论、介质取向和阶次参数的演化规则以及传统的粘弹性。该模型通过跨越六十年应变率的单轴拉伸和压缩数据进行校准。已建立的三维构成模型可以将初始中间原取向和阶次参数作为输入，进行一般加载预测。此外，还进行了参数研究，以进一步了解单域 LCE 与其能量吸收特性相关的速率依赖性。根据参数研究，确定了 LCE 在能量吸收方面优于传统弹性体的特定加载情况。

Self-consistent approximations for the frictionless paraboloidal and conical depth-sensing indentation: The generalized bottom effect

Ivan Argatov, Xiaoqing Jin

doi:10.1016/j.ijsolstr.2024.112713

无摩擦抛物面和锥形深度感应压痕的自洽近似：广义底部效应

The axisymmetric frictionless indentation problem for a linearly-elastic layered medium is considered in the special cases of paraboloidal and conical indenters. A particular focus is placed on incorporating the general substrate effect into the force–displacement relation that is used in the inverse analysis of the depth-sensing indentation curves. A unified analytical modeling approach is developed by further exploring the concept of the indentation scaling factor. The asymptotically exact self-consistent approximations are derived for the dependences of the contact force and the indenter displacement on the contact radius, and their accuracy are tested against the numerically based analytical approximations available in the literature along with the asymptotic approximations. The substrate effect in the Johnson–Kendall–Roberts (JKR)-type adhesion for a paraboloidal or conical indenter is studied in detail.

在抛物面压头和锥形压头的特殊情况下，考虑了线弹性层状介质的轴对称无摩擦压痕问题。重点是将一般基底效应纳入力-位移关系中，该关系用于深度感应压痕曲线的反分析。通过进一步探索压痕缩放因子的概念，开发了一种统一的分析建模方法。针对接触力和压头位移对接触半径的依赖关系，推导出了渐近精确的自洽近似值，并与文献中基于数值的分析近似值和渐近近似值进行了精度测试。详细研究了抛物面或锥形压头在约翰逊-肯德尔-罗伯茨（JKR）型粘附中的基底效应。

Journal of the Mechanics and Physics of Solids

An elastic-damaging cohesive law for cell-substrate adhesion with positive and negative durotaxis

Elena Benvenuti, Gino Antonio Reho

doi:10.1016/j.jmps.2024.105569

细胞-基质粘附的弹性破坏内聚定律与正负杜罗塔西效应

Durotaxis of cells anchored to the extracellular matrix through focal adhesions has been systematically studied through both analytical and computational approaches. However, recent experiments have revealed the attitude of certain cells to unexpectedly migrate towards comparatively softer substrates, thus suggesting the possibility for negative durotaxis to manifest. Cell migration is possible because focal adhesions grow and disrupt, thus operating like adhesive structures undergoing a chemo-physical degradation process. In the present contribution, this degradation process is described through an elastic-damaging cohesive law deduced from a convex-concave pseudo-elastic potential, which confers a variational structure to the mechanical model of the adhesion structure and makes the derivation of analytical solutions possible. Furthermore, the obtained traction-separation cohesive law is amenable to a straightforward implementation into finite element codes. Finite elasticity of the cell body is considered while durotaxis is triggered by applying a contractile pre-stretch to the cell. It is shown that displacement- or force-driven degradation processes may lead to different kinds of durotaxis. The consistency and effectiveness of the proposed approach are showcased in one- and three-dimensional examples of cell-substrate systems.

人们通过分析和计算方法系统地研究了通过焦点粘附固定在细胞外基质上的细胞的杜罗塔斯现象。然而，最近的实验发现，某些细胞会出人意料地向相对较软的基质迁移，从而暗示了负向游走的可能性。细胞迁移之所以可能，是因为局灶粘连会生长和破坏，从而像正在经历化学物理降解过程的粘连结构一样发挥作用。在本文中，这种降解过程是通过凸凹伪弹性势推导出的弹性破坏内聚定律来描述的，它为粘附结构的力学模型赋予了变分结构，并使分析解的推导成为可能。此外，所获得的牵引分离内聚法则可直接应用于有限元代码。在考虑细胞体的有限弹性的同时，通过对细胞施加收缩预拉伸来触发杜罗他西斯。结果表明，位移或力驱动的降解过程可能会导致不同类型的室管膜破裂。在细胞-基质系统的一维和三维实例中，展示了所提方法的一致性和有效性。

Mechanics of Materials

Numerical and experimental evaluations on the defect sensitivity of the performance of BCC truss-lattice structures

Zhenyang Huang, Xiaofei Cao, Hu Niu, Binlin Ma, Xiao Du, Zhiwei Zhou, Haoming Yang, MingKun Du

doi:10.1016/j.mechmat.2024.104937

BCC 桁架-晶格结构性能缺陷敏感性的数值和实验评估

Additive manufacturing (AM) routes have brought abundant geometric defects into as-fabricated lattice materials. Researchers take it for granted that any defects in lattice struts would decrease the mechanical properties of lattice structures, which has also been a rule followed by all engineering designers. In this paper, novel design strategies of actively utilizing defects to improve the mechanical properties of BCC lattice structures are proposed. Firstly, effects of non-periodic microstructure, waving struts and missing struts on the mechanical properties (i.e. compressive modulus and initial yield strength) of BCC lattice structures are investigated through finite element analysis. Simulation results indicate that mechanical properties of the BCC lattice structures exhibited certain sensitivity to the defects. Then, strategies to enhance the performance of BCC lattice patterns by utilizing the imperfections actively are also proposed. Finally, some typical lattice specimens are fabricated and experimental tests are also conducted to validate the accuracy of design strategies. We believe that the proposed new strategy could markedly expand the design space for the development of future materials by actively utilizing the geometric defects.

增材制造（AM）工艺给制造出来的晶格材料带来了大量几何缺陷。研究人员理所当然地认为，晶格支柱中的任何缺陷都会降低晶格结构的机械性能，这也是所有工程设计师遵循的规则。本文提出了积极利用缺陷改善 BCC 晶格结构力学性能的新型设计策略。首先，通过有限元分析研究了非周期性微结构、波浪支杆和缺失支杆对 BCC 网格结构的力学性能（即压缩模量和初始屈服强度）的影响。模拟结果表明，BCC 晶格结构的力学性能对缺陷具有一定的敏感性。然后，还提出了积极利用缺陷来提高 BCC 晶格图案性能的策略。最后，我们制作了一些典型的晶格试样，并进行了实验测试，以验证设计策略的准确性。我们相信，通过积极利用几何缺陷，所提出的新策略可以显著拓展未来材料开发的设计空间。

International Journal of Plasticity

Relating stress/strain heterogeneity to lath martensite strength by experiments and dislocation density-based crystal plasticity

Tim Fischer, Tao Zhou, Carl F.O. Dahlberg, Peter Hedström

doi:10.1016/j.ijplas.2024.103917

通过实验和基于位错密度的晶体塑性将应力/应变异质性与板条马氏体强度联系起来

To enhance the fundamental understanding for micromechanical lath martensite deformation, the microstructure as well as macro- and microscopic tensile properties of as-quenched 15–5 PH stainless steel are systematically analysed depending on the austenitisation temperature. Based on electron backscatter diffraction (EBSD) and backscattered electron (BSE) analysis, it is noted that the martensite morphology alters from a less defined to a more clearly defined parallel arrangement of the block and lath structure with increasing temperature. For an in-depth quantification of the hierarchical boundary strengthening contributions in relation to local stress/strain heterogeneity, separate high-fidelity virtual microstructures are realised for the different scales (prior austenite grains, packets and blocks). This is consistent with the materials transformation process. The virtual microstructures are simulated employing the crystal plasticity finite element method (CPFEM) adapted for handling high dislocation density and encompassing all relevant strengthening mechanisms by boundaries, dislocations and solute atoms. While accurately capturing the measured size-dependent stress–strain behaviour, the simulations reveal in line with the experiments (Hall–Petch) that blocks are the most effective dislocation motion barrier, causing increased strain hardening and stress/strain heterogeneity. Furthermore, since strain localisation is predicted strongest in the distinct block structure, the experimentally observed early plastic material yielding is thought to be favoured here.

为了加深对微观机械板条马氏体变形的基本认识，我们系统分析了奥氏体化温度对淬火后 15-5 PH 不锈钢的微观结构以及宏观和微观拉伸性能的影响。根据电子反向散射衍射（EBSD）和反向散射电子（BSE）分析，可以发现随着温度的升高，马氏体形态从不规则的块状结构转变为更清晰的平行排列的板条状结构。为了深入量化与局部应力/应变异质性相关的分层边界强化贡献，针对不同尺度（先奥氏体晶粒、包和块）实现了独立的高保真虚拟微观结构。这与材料的转变过程是一致的。虚拟微结构采用晶体塑性有限元法（CPFEM）进行模拟，该方法适用于处理高位错密度，并包含边界、位错和溶质原子的所有相关强化机制。模拟准确捕捉了测量到的与尺寸相关的应力-应变行为，同时与实验（霍尔-佩奇）一致，揭示了块体是最有效的位错运动屏障，导致应变硬化和应力/应变异质性增加。此外，由于在独特的块状结构中应变局部性最强，实验观察到的早期塑性材料屈服被认为在这里更有利。

Thin-Walled Structures

Extending Generalized Beam Theory to Allow Cross-Section Discontinuities: Application to Stiffened Thin-Walled Members

Liping Duan, Ji Miao, Jincheng Zhao

doi:10.1016/j.tws.2024.111682

扩展广义梁理论，允许横截面不连续：应用于加固薄壁构件

Thin-walled members with transversal/diagonal stiffeners (e.g., plate girders), from the point of view of the generalized beam theory (GBT), can be treated as beams with discontinuous cross-sections. Generally, it is hard to deal with these members with the classic GBT-based beam finite elements for the presence of stiffeners spoils the continuities of the mode amplitude functions, i.e., one of the essential assumptions in the GBT kinematics. This paper presents an extended GBT (XGBT)-based beam finite element through a combination of the classic GBT with the extended finite element method (XFEM). Specifically, the classic GBT kinematics are used to construct the standard approximation of the cross-section mid-line displacement fields of a beam finite element, and extra enrichment functions which describe the field discontinuities across the beam-stiffener joint edges are added to the standard approximation by using the partition of unity method (PUM). Furthermore, the stiffeners are modelled by shell finite elements, and they are integrated into the extended GBT-based beam model via a three-field mortar method, where the discrete Lagrange multiplier space on each beam-stiffener interface is spanned by the constant functions supported on coarsely partitioned segments over the interface. The implementation of the proposed XGBT formulation is performed via FORTRAN programming and several illustrative examples concerning the linear buckling and statically elastoplastic analyses of stiffened thin-walled beams are employed to accomplish the validation, where the XGBT results are verified by shell finite element results. Results show that the proposed XGBT approach exhibits much lower computational costs for producing equivalently accurate solutions and is much more structurally meaningful than the shell model.

从广义梁理论（GBT）的角度来看，带有横向/对角加劲件的薄壁构件（如板梁）可视为横截面不连续的梁。一般来说，基于 GBT 的经典梁有限元很难处理这些构件，因为加劲梁的存在破坏了模态振幅函数的连续性，而模态振幅函数是 GBT 运动学的基本假设之一。本文通过将经典 GBT 与扩展有限元法（XFEM）相结合，提出了一种基于扩展 GBT（XGBT）的梁有限元。具体来说，经典 GBT 运动学用于构建梁有限元横截面中线位移场的标准近似值，并通过使用统一分割法（PUM）在标准近似值中添加了额外的富集函数，用于描述横梁-加劲件连接边缘的场不连续性。此外，加劲件采用壳有限元建模，并通过三场砂浆法将其集成到基于扩展 GBT 的梁模型中，其中每个梁-加劲件界面上的离散拉格朗日乘数空间由界面上粗分段上支持的常量函数所跨越。通过 FORTRAN 编程实现了所提出的 XGBT 公式，并采用了几个关于加劲薄壁梁线性屈曲和静态弹塑性分析的示例来完成验证，其中 XGBT 结果通过壳体有限元结果进行了验证。结果表明，与壳模型相比，所提出的 XGBT 方法在生成等效精确解时的计算成本要低得多，而且在结构上更有意义。

Numerical simulation of hybrid CFRP/Al hole-clinched joints at different tensile shear loading rates

Weimin Zhuang, Hailun Zhang, Shen Chen

doi:10.1016/j.tws.2024.111698

不同拉伸剪切加载速率下混合 CFRP/Al 孔夹接头的数值模拟

In this study, the tensile-shear damage mechanisms and mechanical responses of carbon fiber reinforced plastic (CFRP)/Al clinched joints were investigated at different loading rates. A continuous damage model was developed that incorporated strain rate effects and nonlinear in-plane shear behaviors. The nonlinear in-plane shear behaviors included two stages: the plastic deformation stage and the strengthening by fiber rotation stage. The finite element algorithm was implemented by applying the VUMAT user subroutine in Abaqus to analyze the responses of the CFRP/Al clinched joints with three layups (orthogonal, diagonal, and hybrid). The experimental and simulation results were highly consistent in terms of the joint failure modes, damage evolution predictions and load–displacement responses. The strain rate effects on CFRP damage were determined. Under high-strain-rate conditions, the average reductions in deformation required for the various damage modes were 51.5%, 13.2% and 13.1% for the orthogonal, diagonal and hybrid layup joints, respectively. Furthermore, the corresponding average area reductions in the damage modes were 16.0%, 41.7% and 70.6%, respectively. Then, the strain rate effects on joint mechanical performance were evaluated. The mechanical properties of the orthogonal layup joints did not exhibit strain rate sensitivity, whereas the energy absorption levels decreased by 21.1% and 36.6% for the diagonal and hybrid layup joints, respectively. For the diagonal layup joints, the maximum load increased by 22.4% under dynamic loading.

本研究探讨了碳纤维增强塑料（CFRP）/铝夹紧接头在不同加载速率下的拉伸剪切损伤机理和机械响应。研究建立了一个包含应变率效应和非线性面内剪切行为的连续损伤模型。非线性面内剪切行为包括两个阶段：塑性变形阶段和纤维旋转强化阶段。有限元算法是通过在 Abaqus 中应用 VUMAT 用户子程序来实现的，以分析 CFRP/Al 三种铺层（正交、对角和混合）咬合接头的响应。实验和模拟结果在接头失效模式、损伤演变预测和载荷-位移响应方面高度一致。研究还确定了应变速率对 CFRP 损伤的影响。在高应变率条件下，正交、对角和混合铺层接头的各种损坏模式所需的变形平均减小率分别为 51.5%、13.2% 和 13.1%。此外，在各种损坏模式下，相应的平均面积减少率分别为 16.0%、41.7% 和 70.6%。然后，评估了应变率对接头机械性能的影响。正交层叠接头的机械性能没有表现出应变速率敏感性，而对角层叠接头和混合层叠接头的能量吸收水平分别降低了 21.1% 和 36.6%。对于对角铺层接头，在动态载荷下的最大载荷增加了 22.4%。