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【新文速递】2024年5月8日固体力学SCI期刊最新文章

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今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 2 篇,Thin-Walled Structures 4 篇

International Journal of Solids and Structures

Modelling the magnetic-mechanical coupled viscoelastic behaviour of transversely isotropic soft magnetorheological elastomers

Bochao Wang, Leif Kari, Huaxia Deng, Xinglong Gong

doi:10.1016/j.ijsolstr.2024.112863

横向各向同性软磁流变弹性体的磁-力耦合粘弹性行为建模

Soft magnetorheological elastomers (s-MRE) is a kind of smart material mainly fabricated by embedding soft magnetic particles into an elastomer matrix. It can be categorized as isotropic and transversely isotropic, depending on the arrangement of internal magnetic particles. In isotropic s-MRE, magnetic particles are randomly distributed, while transversely isotropic s-MRE forms chain structures for the magnetic particles. Compared with isotropic s-MRE, transversely isotropic s-MRE exhibits more significant magnetically-enhanced mechanical properties, making it highly applicable in the vibration control area. While past theoretical work has mainly focused on the magneto-mechanical coupling behaviour of isotropic s-MRE, less attention has been given to modelling the magneto-mechanical coupling behaviour of transversely isotropic s-MRE. Specifically, understanding the impact of different particle chain-magnetic field spatial locations on the magnetization and magnetic-enhanced viscoelastic behaviour of transversely isotropic s-MRE remains an open topic. To address this research gap, we characterize the quasi-static, viscoelastic and magnetization performance of transversely isotropic s-MRE under different particle chain-magnetic field spatial locations. Subsequently, we develop a novel constitutive model for transversely isotropic s-MRE, integrating magneto-hyperelasticity, magneto-viscoelasticity and magnetization. We then implement the magneto-mechanical coupled model for transversely isotropic s-MRE at a finite element level. Following model calibration and validation, we conduct a case study to demonstrate the model’s ability to predict the magneto-mechanical coupling performance of a transversely isotropic s-MRE-based laminated isolator. This model is a valuable tool for predicting the magneto-mechanical performance of transversely isotropic s-MRE-based smart devices, thereby facilitating the design and advancement of transversely isotropic s-MRE in vibration control.

软磁流变弹性体(s-MRE)是一种主要通过在弹性体基体中嵌入软磁微粒而制备的智能材料。根据内部磁粒子的排列,它可以分为各向同性和横向各向同性。在各向同性s-MRE中,磁性颗粒是随机分布的,而横向各向同性s-MRE中磁性颗粒形成链状结构。与各向同性s-MRE相比,横向各向同性s-MRE表现出更显著的磁增强力学性能,在振动控制领域具有很高的应用价值。过去的理论工作主要集中在各向同性s-MRE的磁-力耦合行为上,而对横向各向同性s-MRE的磁-力耦合行为的建模关注较少。具体来说,了解不同粒子链磁场空间位置对横向各向同性s-MRE磁化和磁增强粘弹性行为的影响仍然是一个开放的话题。为了解决这一研究空白,我们对不同粒子链磁场空间位置下横各向同性s-MRE的准静态、粘弹性和磁化性能进行了表征。随后,我们建立了一个新的横向各向同性s-MRE本构模型,将磁-超弹性、磁-粘弹性和磁化相结合。然后,我们在有限元水平上实现了横向各向同性s-MRE的磁-力耦合模型。在模型校准和验证之后,我们进行了一个案例研究,以证明该模型能够预测基于横向各向同性s- mre的层压隔离器的磁-力耦合性能。该模型为预测基于横各向同性s-MRE的智能设备的磁力学性能提供了有价值的工具,从而为横各向同性s-MRE在振动控制中的设计和推进提供了便利。


Journal of the Mechanics and Physics of Solids

Interlocked wood-like composites with tunable mechanical properties

Hui Liu, Xu Wang, Lei Wan, Juan Hao, Yujie Zhong, Zhengyi Mao, Heyi Wang, Zhaowenbo Cao, Shaogang Wang, Jian Lu

doi:10.1016/j.jmps.2024.105679

具有可调机械性能的互锁类木复合材料

Inspired by the fact that the architecture of natural biomaterials has a great influence on their mechanical properties, the present work designed a Al2O3–poly (methyl methacrylate) composite with an interlocked wood-like architecture, which can balance the contradictions between flexural strength–fracture toughness. The results shows that the mechanical performance of the composites can be tuned through the adjustment of the tilt angle of the Al2O3 spiral fibres. The composite with a tilt angle of 30° exhibited the highest flexural strength and fracture toughness, showing the ability to overcome the trade-off between flexural strength and fracture toughness. All composites exhibited weak compressive strength anisotropy owing to the interlocked helical architecture in which the continuous fiber spiraled in 3D space. Toughening mechanisms including crack deflection, crack bridging, crack bifurcation, microcracking were observed. Numerous microcracks were nucleated in the Al2O3 ceramic skeleton, and they propagated along the main crack under the bridging effect of poly (methyl methacrylate). All of the composites featured suture-like cracks perpendicular to the direction of the main cracks, which was a unique toughening mechanism found in this architecture. Large-size composites can be prepared through the adopted technique to meet the demands of engineering applications.

受天然生物材料的结构对其力学性能影响很大的启发,本工作设计了一种具有连锁木状结构的al2o3 -聚甲基丙烯酸甲酯复合材料,可以平衡弯曲强度与断裂韧性之间的矛盾。结果表明,通过调整Al2O3螺旋纤维的倾斜角度可以调节复合材料的力学性能。倾角为30°的复合材料具有最高的抗弯强度和断裂韧性,显示出克服抗弯强度和断裂韧性之间权衡的能力。所有复合材料的抗压强度各向异性都较弱,这是由于连续纤维在三维空间中螺旋缠绕的连锁螺旋结构造成的。观察了裂纹挠曲、裂纹桥接、裂纹分岔和微裂纹等增韧机制。在Al2O3陶瓷骨架中形成大量微裂纹,并在聚甲基丙烯酸甲酯的桥接作用下沿主裂纹扩展。所有复合材料都具有垂直于主裂纹方向的缝合线状裂纹,这是该结构中发现的一种独特的增韧机制。采用该技术可制备大尺寸复合材料,满足工程应用的需要。


Cracking of Soft Collagenous Tissues under Suture Retention

Jingda Tang, Jiayi Lin, Tiejun Wang

doi:10.1016/j.jmps.2024.105682

缝线保留下软胶原组织开裂

Soft collagenous tissues consist of collagen fibers and soft matrix, such as skin, muscle, and heart valve, etc. Suture of the tissues is ubiquitous in surgery, which may cause fracture of tissues due to inevitably introduced defects. However, the cracking mechanism of soft collagenous tissues under suture retention remains elusive. Herein, we use bovine pericardium as a model tissue to study the suture related fracture considering various fiber orientations. Fracture tests reveal distinct toughness and fracture modes of the tissue depending on the fiber orientation, such as crack propagation and crack deflection. The maximum J-integral criterion has been established to predict the direction of crack propagation in the tissue. We further conduct suture retention test to evaluate the suture resistance of tissues, and find two different failure modes: fracture and cutting. Microscopic examination of the fracture surface demonstrates that the tissue can rupture with long fiber pullout, cut through matrix failure, or cut by a combination of fiber break and pullout. The cohesive element model is used to analyze the cutting mode. The predicted failure modes and force-displacement curves match well with experiments. This paper may provide guidance to surgical operations and benefit new artificial collagenous materials.

软胶原组织由胶原纤维和软基质组成,如皮肤、肌肉、心脏瓣膜等。手术中组织缝合无处不在,不可避免地会引入缺陷,导致组织断裂。然而,软胶原组织在缝线保留下的开裂机制尚不清楚。在此,我们以牛心包为模型组织,考虑不同的纤维取向来研究与缝合线相关的骨折。断裂试验揭示了不同纤维取向的组织的不同韧性和断裂模式,如裂纹扩展和裂纹挠曲。建立了最大j积分准则来预测裂纹在组织中的扩展方向。我们进一步进行缝合保留试验,评估组织的缝合阻力,发现两种不同的破坏模式:断裂和切割。断口表面的显微检查表明,组织可因长纤维拉出而破裂,可因基质破坏而切割,或因纤维断裂和拉出而切割。采用内聚元模型对切削模式进行分析。预测的破坏模式和力-位移曲线与试验结果吻合较好。本文可为外科手术提供指导,并有利于新型人工胶原材料的开发。


Thin-Walled Structures

Initial load factor adjustment through genetic algorithm for the generalized displacement control method: Implementation on non-rigid origami analysis

Ali Maghami, Seyed Mahmoud Hosseini

doi:10.1016/j.tws.2024.111972

基于遗传算法的初始载荷因子调整广义位移控制方法:在非刚性折纸分析中的实现

The nonlinear analysis of structural systems relies on effective nonlinear solution schemes, known as nonlinear solvers or path-following methods. This paper explores the challenge of determining the initial load factor in such analyses, with a particular focus on complex origami structures. This study presents a novel approach that leverages genetic algorithms (GA) to efficiently determine the initial load factor for the generalized displacement method. Building upon the concept of stiffness parameters, our method offers a systematic solution. In this work, GA serves as a tool to discover the appropriate initial load factor based on changes in the stiffness parameter, providing a more rational and user-friendly approach. To demonstrate the practical applicability of our approach, we apply it to a range of complex origami problems, including the folding of Miura-ori, folding of an egg-box origami, bending of an egg-box origami, and folding of an arc Miura-ori. These examples, along with a truss example, encompass highly nonlinear behaviors, including limit points, extreme stiffness fluctuations, snap-through, and snap-back. Our results showcase the effectiveness of our method in accurately tuning the initial load factor to capture and track intricate nonlinear behaviors. Furthermore, it offers the flexibility to fine-tune the distribution of points along the path and manage the resolution of the depicted equilibrium path. This versatility underscores its potential applications in fields such as deployable structures and complex large deformation structural analysis.

结构系统的非线性分析依赖于有效的非线性解方案,即非线性求解器或路径跟踪方法。本文探讨了在这种分析中确定初始载荷因子的挑战,特别关注复杂的折纸结构。本文提出了一种利用遗传算法有效确定广义位移法初始载荷因子的新方法。基于刚度参数的概念,我们的方法提供了一个系统的解决方案。在这项工作中,遗传算法作为一种工具,根据刚度参数的变化发现适当的初始载荷因子,提供了一种更合理和用户友好的方法。为了证明我们的方法的实际适用性,我们将其应用于一系列复杂的折纸问题,包括Miura-ori的折叠,蛋盒折纸的折叠,蛋盒折纸的弯曲,以及弧Miura-ori的折叠。这些示例以及桁架示例包含高度非线性行为,包括极限点、极端刚度波动、跳穿和跳回。我们的结果显示了我们的方法在精确调整初始负载因子以捕获和跟踪复杂的非线性行为方面的有效性。此外,它还提供了沿路径微调点分布的灵活性,并管理所描述的平衡路径的分辨率。这种多功能性强调了其在可展开结构和复杂大变形结构分析等领域的潜在应用。


Geometry-force interactive design and optimization method of cable dome structures

Suduo Xue, Xuanzhi Li, Xiongyan Li

doi:10.1016/j.tws.2024.111977

索穹顶结构几何-力交互设计及优化方法

Cable dome is a typical flexible structural system. Its initial geometry determines the prestress distribution and affects the structural performance. Using geometric parameters to establish the mechanical equation of initial state can effectively realize the geometric-force interactive design and optimization of cable dome structure. Consequently, a standardized equation is established in this paper to uniformly express the geometric-force relationship, utilizing a feasible prestress distribution function expressed by geometric parameters. Subsequently, an interactive design method for initial geometry and prestress is presented. The proposed method is theoretically expounded in terms of geometric design, prestress design and shape optimization. Two typical cable dome cases, Geiger and Levy, are successfully applied to accomplish the geometric-force design and optimization of the initial state. The results show that the efficient design of initial state can be completed by establishing the interaction between geometry and force without repeated algebraic calculation. The optimized initial geometry can significantly improve the Structural stiffness.

索穹顶是一种典型的柔性结构体系。其初始几何形状决定了预应力分布,影响结构性能。利用几何参数建立初始状态力学方程,可以有效地实现索穹顶结构的几何-力交互设计与优化。因此,本文利用可行的几何参数表示的预应力分布函数,建立了统一表示几何-力关系的标准化方程。在此基础上,提出了初始几何与预应力的交互设计方法。从几何设计、预应力设计和形状优化三个方面对该方法进行了理论阐述。采用Geiger和Levy两种典型的索穹顶案例,成功地完成了初始状态的几何力设计和优化。结果表明,通过建立几何与力之间的相互作用,无需重复代数计算,即可完成初始状态的有效设计。优化后的初始几何形状能显著提高结构刚度。


A generalizable framework of solution-guided machine learning with application to nanoindentation of free-standing thin films

Ruijin Wang, Tianquan Ying, Yang Chen, Fangyan Zhu, Jiantao Leng, Tienchong Chang, Tongyi Zhang, Huajian Gao

doi:10.1016/j.tws.2024.111984

求解导向机器学习的通用框架及其在独立薄膜纳米压痕中的应用

Despite the significant success of machine learning (ML) in various fields, there remains a critical need to enhance its ability to extrapolate from insufficient data. Here, we propose a generalizable framework called solution-guided machine learning (SGML), which integrates existing solutions as additional features to supplement limited training data. Our application of SGML to nanoindentation of free-standing thin films demonstrates robust performance, including good training convergence, accuracy, and extrapolation. Notably, the SGML models trained on limited data are able to be applied across a wider range of scenarios, e.g., the model trained on relatively moderate indenter sizes applies to relatively small as well as large indenter sizes, and the model trained for graphene successfully extends its applicability to other 2D nanomaterials (e.g., MoS2) and even to microscale thin films (e.g., silicone), highlighting extraordinary extrapolation performance. We discuss also the cooperative relationship between solutions and data, further confirming that the enhanced performance of SGML is attributed to the complementary information supplemented by solutions to data. This work presents a robust method to train more powerful ML models by combining known knowledge with limited data, offering great potential for addressing complex problems that often suffer from data insufficiency.

尽管机器学习(ML)在各个领域取得了重大成功,但仍然迫切需要增强其从不足数据中推断的能力。在这里,我们提出了一个可推广的框架,称为解决方案引导机器学习(SGML),它将现有的解决方案集成为附加特征,以补充有限的训练数据。我们将SGML应用于独立薄膜的纳米压痕,展示了强大的性能,包括良好的训练收敛性、准确性和外推性。值得注意的是,在有限数据上训练的SGML模型能够应用于更广泛的场景,例如,在相对适中的压头尺寸上训练的模型适用于相对较小和较大的压头尺寸,并且为石墨烯训练的模型成功地将其适用性扩展到其他2D纳米材料(例如MoS2)甚至微尺度薄膜(例如硅胶),突出了非凡的外推性能。我们还讨论了解决方案和数据之间的合作关系,进一步证实了SGML性能的增强归功于解决方案对数据的补充信息。这项工作提出了一种鲁棒的方法,通过将已知知识与有限的数据相结合来训练更强大的ML模型,为解决经常遭受数据不足的复杂问题提供了巨大的潜力。


Energy absorption in expanding metallic wire mesh tubes

Wangfan Zhou, Dora Karagiozova, Xudong Ren, Guoxing Lu

doi:10.1016/j.tws.2024.111981

膨胀金属丝网管的能量吸收

The deformation process and energy absorption of metal wire mesh tubes under quasi-static expanding by a hemispherical-cylindrical indenter were investigated by experimental tests, finite element (FE) simulations and analytical modelling. Stainless steel and aluminum alloy tubes were tested on an MTS universal testing machine at a speed of 10 mm/min. The effects of mesh cell size and friction coefficient on the quasi-static force and specific energy absorption (SEA) were examined by FE analysis and analytical modelling. The analysis reveals that a combination of the mesh cell size and cross section dimension of the wire governs the energy absorption of tubes of equal overall dimension (diameter and length) and masses. In general, a decrease of the size of cells with constant height-to-width ratios leads to an increase of the specific energy absorption mainly due to the increased number of cells within the deformed region. An increase of the specific energy absorption is also achieved when the cell size is reduced by only decreasing the cell height. The maximum indenter force predicted by the proposed analytical model of the expanded tube deformation agrees well with the experimental results and FE simulations.

采用实验试验、有限元模拟和分析模型,研究了金属丝网管在半圆圆柱压头准静态膨胀作用下的变形过程和吸能特性。不锈钢管和铝合金管在MTS万能试验机上以10 mm/min的速度进行测试。通过有限元分析和解析建模,考察了网格尺寸和摩擦系数对准静力和比能吸收(SEA)的影响。分析表明,网孔尺寸和丝的横截面尺寸的组合决定了管的总尺寸(直径和长度)和质量相等的吸能。一般来说,在等高宽比下,减小细胞的尺寸会导致比能量吸收的增加,这主要是由于变形区域内细胞数量的增加。当仅通过降低电池高度来减小电池尺寸时,也实现了比能量吸收的增加。所建立的膨胀管变形分析模型所预测的最大压头力与实验结果和有限元模拟结果吻合较好。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemInspireMAGNET振动断裂复合材料非线性形状优化通用裂纹理论材料控制试验
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【新文速递】2024年5月10日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 5 篇,Journal of the Mechanics and Physics of Solids 1 篇,Thin-Walled Structures 4 篇International Journal of Solids and StructuresA novel strength-energy criterion for bimaterial interface crack propagationPing Li, Qian Shao, Liang Li, Jie Yang, Qun Huang, Ahmed Makradi, Heng Hudoi:10.1016/j.ijsolstr.2024.112864双材料界面裂纹扩展的一种新的强度-能量准则This paper aims to propose a novel fracture criterion to predict complex propagation behaviors of a bimaterial interface crack, either delaminating along the interface or kinking out of the interface into one of the adjoining materials. A strength-based criterion is used to predict the crack deflection, and an energy-based criterion is adopted to assess delamination along the interface. To determine the competition between these two cracking modes, a competing strategy is developed by comparing the strength-based and energy-based criteria. This coupled strength-energy fracture criterion eliminates the disadvantages arising from a criterion based solely on strength or energy, and is convenient to be calculated and embedded into numerical models. As practice, we embed the criterion into a homemade extended finite element model to simulate bimaterial interface crack propagation. Several numerical examples are performed to verify the effectiveness and accuracy of the developed model. Finally, this model is applied to simulate an interface crack propagation in a sandwich structure that has a specially designed peel-stopper. Parametric studies reveal that the material and interface toughness as well as geometrical dimensions of the structure have significant effects on the propagation mode of the interface crack. The results provide practical suggestions on the optimal design of peel-stopper in sandwich structures.本文旨在提出一种新的断裂准则来预测双材料界面裂纹的复杂扩展行为,即沿界面剥离或从界面中扭出到相邻材料之一。采用基于强度的准则来预测裂纹挠度,采用基于能量的准则来评估沿界面的分层。为了确定这两种开裂模式之间的竞争,通过比较基于强度和基于能量的准则,制定了一种竞争策略。这种强度-能量耦合断裂准则消除了单纯基于强度或能量准则的缺点,便于计算和嵌入数值模型。作为实践,我们将该准则嵌入到自制的扩展有限元模型中来模拟双材料界面裂纹扩展。算例验证了所建模型的有效性和准确性。最后,将该模型应用于具有特殊设计的剥离塞的夹层结构中界面裂纹扩展的模拟。参数化研究表明,材料、界面韧性以及结构的几何尺寸对界面裂纹的扩展模式有显著影响。研究结果为夹层结构中止水带的优化设计提供了实用建议。A multiscale bifurcation analysis using micromechanical-based constitutive tensor for granular materialMojtaba Farahnak, Richard Wan, Mehdi Pouragha, François Nicotdoi:10.1016/j.ijsolstr.2024.112866基于微力学本构张量的颗粒材料多尺度分岔分析The current study presents a multiscale approach that investigates material instability and localization phenomena in plastic granular materials and the discrete-continuum duality. A bifurcation and stability analysis in continuum mechanics usually requires the material’s tangent (stiffness) operator, the computation of which in a micromechanical approach such as Discrete Element Modeling (DEM) requires specific treatment. To bridge the discrete and continuum worlds, a new computational approach incorporating strain probing is proposed to reconstruct the elastoplastic constitutive tensor and its spectral characteristics from DEM simulations. The probing technique permits the computation of the tangent operator that inherits microstructural information from the discrete world to analyze bifurcation in elastoplasticity at the macro level. An incrementally linear constitutive tensor is computed, distinct for each of the ensemble of probing directions belonging to a particular tensorial zone or sector of incremental stress or strain space, thus making it directionally non-linear. Following such an approach, material instability can be evaluated from the spectral characteristics of the tangent constitutive tensor deduced from DEM probing calculations belonging to an identified tensorial zone. A meso-scale analysis is finally offered to detect shear band localization through the well-known Rice’s criterion as a continuum-based concept extended to a micromechanical discrete modeling framework. These new numerical results show that the multiscale proposed approach, which allows access to microstructural information, is consistent with a continuum one such as when predicting the localization angle during shear banding in a granular specimen in DEM.本研究提出了一种多尺度方法来研究塑性颗粒材料中的材料不稳定性和局部化现象以及离散-连续二象性。连续介质力学中的分岔和稳定性分析通常需要材料的切线(刚度)算符,而在离散元建模(DEM)等微力学方法中,其计算需要特殊处理。为了跨越离散和连续世界,提出了一种结合应变探测的新计算方法,从DEM模拟中重建弹塑性本构张量及其谱特征。探测技术允许计算从离散世界中继承微观结构信息的切线算子,从而在宏观层面上分析弹塑性的分岔。计算增量线性本构张量,对于属于特定张量区域或增量应力或应变空间扇区的探测方向的每个集 合都是不同的,从而使其方向非线性。按照这种方法,材料的不稳定性可以从属于确定张量区域的DEM探测计算推导出的切本构张量的频谱特征来评估。最后提供了一个中尺度分析,通过著名的Rice准则作为一个基于连续体的概念扩展到微力学离散建模框架,来检测剪切带的局部化。这些新的数值结果表明,所提出的多尺度方法可以获得微观结构信息,与连续体方法一致,例如在DEM中预测颗粒试样剪切带过程中的局部化角。Homogenization of non-Darcy flow in porous media containing spheroidal impervious inclusionsV. Monchietdoi:10.1016/j.ijsolstr.2024.112867含球形不透水夹杂物的多孔介质中非达西流的均匀化The aim of the present study is to determine the nonlinear filtration law of a porous medium containing spheroidal impervious inclusions through a homogenization framework. At the local scale, it is assumed that the fluid flow through the porous solid surrounding the inclusions obeys the Forchheimer equation. The macroscopic law is derived in the field of nonlinear variational approach applied to some representative cell, namely a porous spheroid containing a single centered spheroidal inclusion confocal to the outer. Both a static and kinematical approach are developed to bound the overall filtration properties of the heterogeneous solid. Appropriate trial fields are considered to determine closed-form estimates and are obtained from the solution of a linear problem replacing the Forchheimer law in the porous solid at the microscopic scale by the Darcy law. The analytic estimates are calculated through some approximations and lead to accurate solutions of the nonlinear problems. Finally, the analytic models are compared with FFT solutions in the case of a regular array of spheroidal impervious inclusions.本研究的目的是通过均匀化框架确定含有球形不透水夹杂物的多孔介质的非线性过滤规律。在局部尺度上,假定流体在包裹体周围多孔固体中的流动符合Forchheimer方程。将非线性变分方法应用于具有代表性的胞体,即含有单中心球体共聚焦的多孔球体,得到了宏观规律。采用静态和运动学两种方法来确定非均质固体的整体过滤特性。考虑适当的试验场来确定封闭形式的估计,并从用达西定律代替多孔固体微观尺度上的Forchheimer定律的线性问题的解中得到。通过一些近似计算得到解析估计,从而得到非线性问题的精确解。最后,将解析模型与规则的球形不透水夹杂物阵列的FFT解进行了比较。Indentation of a thin incompressible layer with finite frictionJ.R. Barber, S. Stupkiewiczdoi:10.1016/j.ijsolstr.2024.112868有限摩擦下薄的不可压缩层的压痕If a thin layer of an incompressible elastic material is pressed between two plane surfaces, the effective stiffness is very sensitive to the presence of frictional slip. This effect is investigated using a low-order polynomial representation of the through-thickness displacement profile. Results show good agreement with finite element studies and also show that the stiffness is significantly affected by that part of the layer [if any] outside the loaded region. The same result is then used in convolution to approximate the load–displacement response for a convex indenter.如果在两个平面之间压上一层薄的不可压缩弹性材料,则有效刚度对摩擦滑移的存在非常敏感。利用低阶多项式表示的全厚度位移剖面来研究这种效应。结果与有限元研究结果很好地吻合,并且还表明刚度受到加载区域外的那部分层[如果有的话]的显著影响。然后将相同的结果用于卷积来近似凸压头的载荷-位移响应。Effective characterization for the dynamic indentation and plastic parameters acquisition of metalsGesheng Xiao, Bowen Si, Erqiang Liu, Li Qiao, Yuhong Ma, Xuefeng Shudoi:10.1016/j.ijsolstr.2024.112872金属动态压痕的有效表征和塑性参数的获取As a fundamental test technique for the mechanical properties of materials, indentation shows broad application prospects. Compared to the well-studied quasi-static indentation, relatively few and incomplete studies on the dynamic indentation test and characterization have been performed. In this work, a dynamic indentation test technique based on the split Hopkinson pressure bar system is developed, and the corresponding “three-wave method” is proposed to effectively acquire the time-resolved dynamic indentation load and depth. Systematic indentation tests under different loading rates and indenter cone angles are conducted on typical metal materials such as Cu, α-Fe, and α-Ti. Based on the dynamic indentation contact stiffness analysis and indentation theory the indentation hardness under different loading conditions are determined. A procedure for plastic parameter inversion of metal materials, including strain hardening and strain rate strengthening terms based on dynamic indentation, is provided. The effectiveness is verified by the traditional compression test results, providing a new method for characterizing the dynamic mechanical properties of metal materials.压痕作为材料力学性能的一项基本测试技术,具有广阔的应用前景。相对于研究较多的准静态压痕,对动态压痕测试和表征的研究相对较少和不完整。本文提出了一种基于分离式霍普金森压杆系统的动态压痕试验技术,并提出了相应的“三波法”,以有效获取时间解析的动态压痕载荷和深度。对Cu、α-Fe、α-Ti等典型金属材料在不同加载速率和压头锥角下进行了系统的压痕试验。基于动态压痕接触刚度分析和压痕理论,确定了不同载荷条件下的压痕硬度。提出了一种基于动态压痕的金属材料塑性参数反演方法,包括应变硬化项和应变速率强化项。通过传统的压缩试验结果验证了该方法的有效性,为表征金属材料的动态力学性能提供了一种新的方法。Journal of the Mechanics and Physics of SolidsElastic solids under frictionless rigid contact and configurational forceFrancesco Dal Corso, Marco Amato, Davide Bigonidoi:10.1016/j.jmps.2024.105673 无摩擦刚性接触和构形力作用下的弹性固体A homogeneous elastic solid, bounded by a flat surface in its unstressed configuration, undergoes a finite strain when in frictionless contact against a rigid and rectilinear constraint, ending with a rounded or sharp corner, in a two-dimensional formulation. With a strong analogy to fracture mechanics, it is shown that (i.) a path-independent J –integral can be defined for frictionless contact problems, (ii.) which is equal to the energy release rate G associated with an infinitesimal growth in the size of the frictionless constraint, and thus gives the value of the configurational force component along the sliding direction. Furthermore, it is found that (iii.) such a configurational sliding force is the Newtonian force component exerted by the elastic solid on the constraint at the frictionless contact. Assuming the kinematics of an Euler–Bernoulli rod for an elastic body of rectangular shape, the results (i.)–(iii.) lead to a new interpretation from a nonlinear solid mechanics perspective of the configurational forces recently disclosed for one-dimensional structures of variable length. Finally, approximate but closed-form solutions (validated with finite element simulations) are exploited to provide further insight into the effect of configurational forces. In particular, two applications are presented which show that a transverse compression can lead to Eulerian buckling or to longitudinal dynamic motion, both realizing novel examples of soft actuation mechanisms. As an application to biology, our results may provide a mechanical explanation for the observed phenomenon of negative durotaxis, where cells migrate from stiffer to softer environments.一种均匀的弹性固体,以其无应力形态的平面为界,在与刚性和直线约束的无摩擦接触中经历有限应变,以二维形式以圆角或尖角结束。通过与断裂力学的强烈类比,表明:(i)对于无摩擦接触问题可以定义一个路径无关的J积分,(ii)它等于与无摩擦约束尺寸的无限小增长相关的能量释放率G,从而给出沿滑动方向的构型力分量的值。进一步发现(iii)这种构形滑动力是弹性固体在无摩擦接触处施加在约束上的牛顿力分量。假设矩形弹性体的欧拉-伯努利杆的运动学,结果(i.) - (iii.)从非线性固体力学的角度对最近揭示的一维变长结构的构形力进行了新的解释。最后,利用近似但封闭形式的解(通过有限元模拟验证)来进一步深入了解构型力的影响。特别地,给出了两个应用,表明横向压缩可以导致欧拉屈曲或纵向动力运动,两者都实现了软驱动机构的新例子。作为生物学上的应用,我们的研究结果可能为观察到的细胞从较硬的环境迁移到较软的环境的负硬性现象提供了一个力学解释。Thin-Walled StructuresNonlinear statics of magneto-electro-elastic nanoplates considering flexomagnetoelectric effect based on nonlocal strain gradient theoryLiang Liang Xu, Yu Fang Zheng, Chang Ping Chendoi:10.1016/j.tws.2024.111974基于非局部应变梯度理论的考虑柔磁电效应的磁电弹性纳米片的非线性静力学The nonlinear static behavior of hygrothermal magnetoelectroelastic(MEE) nanoplates considering the flexomagnetoelectric (FME) effect is researched by engaging the first-order shear deformation theory (FSDT). The constitutive equations of MEE nanoplates take into account the FME effect and hygrothermal effect. Leveraging the FSDT, von Karman's nonlinear equation and Hamilton's principle, the nonlinear control equation for hygrothermal MEE nanoplates can be derived by using the variational approach. The nonlocal strain gradient theory (NSGT) has application in the size effect of MEE nanoplates. The nonlocal nonlinear term in the control equation is handled by employing the Airy stress function, and then the non-linear mechanical model is solved by the Galerkin method. Thus, the nonlinear load-deflection curves (NLDC) of the MEE nanoplate are obtained via the introduction of material parameters, enabling an examination of the impact of various factors such as the FME effect, two small size parameters of NSGT and other parameters on the nonlinear bending behavior of MEE nanoplates. In conclusion, this study offers a theoretical foundation for taking into account the FME effect in the development of nanodevices, thereby contributing to advancements in this field.利用一阶剪切变形理论(FSDT)研究了考虑柔磁电效应的湿热电磁弹性(MEE)纳米片的非线性静态行为。MEE纳米板的本构方程考虑了FME效应和湿热效应。利用FSDT、von Karman非线性方程和Hamilton原理,采用变分方法推导了热湿MEE纳米板的非线性控制方程。非局部应变梯度理论(NSGT)应用于MEE纳米板的尺寸效应。采用Airy应力函数处理控制方程中的非局部非线性项,然后采用伽辽金法求解非线性力学模型。因此,通过引入材料参数获得了MEE纳米板的非线性载荷-挠曲曲线(NLDC),从而可以研究FME效应、两个小尺寸NSGT参数和其他参数等各种因素对MEE纳米板非线性弯曲行为的影响。总之,本研究为在纳米器件的开发中考虑FME效应提供了理论基础,从而促进了该领域的发展。Mechanical and piezoresistive performance of additively manufactured carbon fiber/PA12 hybrid honeycombsJ Jefferson Andrew, Mohammed Ayaz Uddin, S Kumar, Andreas Schifferdoi:10.1016/j.tws.2024.111950 增材制造碳纤维/PA12混合蜂窝的机械性能和压阻性能This study investigates a novel self-sensing honeycomb composite structure composed of two distinct cellular layers with differing unit cell architectures, specifically hexagonal and re-entrant designs. Short carbon fiber (CF)/polyamide 12 (PA12) composite filaments with 0, 5 or 15 wt.% CF content were utilized to additively manufacture the honeycomb structures via Fused Filament Fabrication (FFF), and their mechanical and piezoresistive self-sensing characteristics were experimentally investigated under quasi-static in-plane and out-of-plane compression at both room temperature and elevated temperatures. The results reveal that the hybrid hexagonal/re-entrant (HR) honeycombs mechanically outperform their non-hybrid double-layer and single-layer counterparts under in-plane loading, reporting an increase in collapse strength and energy absorption by factors of 1.64 and 2.25, respectively. These improvements are attributed to the mechanical interactions occurring at the interface between the auxetic and non-auxetic layers within the hybrid structure, effectively enhancing its structural attributes. Furthermore, the double-layer honeycombs display excellent strain-sensing capabilities within the elastic regime, with gauge factors reaching values as high as 146. Mechanical tests conducted at elevated temperatures reveal that the CF/PA12 honeycombs retain a significant portion of their elastic modulus, strength and energy absorption even at 125°C, while maintaining high gauge factors of up to 72.4. These honeycombs also exhibit pronounced thermoresistive behavior, evidenced by a decrease in electrical resistance of up to 41.3% with increasing temperatures from 25 to 125°C. Considering their exceptional combination of thermo-mechanical, thermoresistive and piezoresistive characteristics, these hybrid double-layered CF/PA12 honeycombs hold promise for potential applications in multifunctional lightweight structures, offering integrated temperature and strain-sensing capabilities.本研究研究了一种新型的自传感蜂窝复合结构,该结构由两个不同的细胞层组成,具有不同的单位细胞结构,特别是六角形和重入式设计。利用CF含量分别为0、5、15 wt.%的短碳纤维(CF)/聚酰胺12 (PA12)复合长丝,采用熔融长丝法(FFF)增材制造蜂窝结构,并对其在室温和高温准静态面内和面外压缩下的力学和压阻自传感特性进行了实验研究。结果表明,在面内载荷作用下,混合六方/重入(HR)蜂窝的力学性能优于非混合双层和单层蜂窝,其崩塌强度和能量吸收分别提高了1.64和2.25倍。这些改进是由于杂化结构中失活层和非失活层之间发生的力学相互作用,有效地增强了其结构属性。此外,双层蜂窝在弹性范围内表现出优异的应变传感能力,其测量因子高达146。在高温下进行的机械测试表明,即使在125°C下,CF/PA12蜂窝也能保持其弹性模量、强度和能量吸收的很大一部分,同时保持高达72.4的高测量系数。这些蜂窝还表现出明显的耐热性,当温度从25°C增加到125°C时,电阻下降高达41.3%。考虑到其独特的热机械、热阻和压阻特性的组合,这些混合双层CF/PA12蜂窝在多功能轻质结构中具有潜在的应用前景,提供集成的温度和应变传感功能。On thermal and strain-rate dependences of polymethacrylimide (PMI) foam materialsXintao Huo, Zhongcheng Jiang, Xianguang Gu, Quantian Luo, Qing Li, Guangyong Sundoi:10.1016/j.tws.2024.111986 聚甲基丙烯酰亚胺(PMI)泡沫材料的热及应变速率依赖性研究Polymethacrylimide (PMI) foams exhibit great potentials in engineering applications thanks to its outstanding lightweight and superior mechanical properties. However, the temperature and loading rate can greatly affect its mechanical behaviors, which are the key factors in analysis and design of the PMI foam structures for practical applications. Unfortunately, there is lack of fundamental data and constitutive models available concerning the elastic-plastic properties of the PMI foam in various stress states at different ambient temperatures and different strain rates. Therefore, this study aims to fill this knowledge gap by generating basic experimental data and providing a generic modeling solution for PMI foam materials and structures. To better reflect the actual service conditions in practice, different stress states are considered under different temperatures and strain rates. The cyclic loads are applied to characterize the actual mechanical responses of the PMI foam where the initial and subsequent yield surfaces were calibrated and analyzed. Following the experimental results, the elasticity, plasticity, viscosity and damage of the PMI foam are investigated thoroughly, especially for the initial and subsequent yielding behaviors. Further, the thermal and strain rate dependent constitutive models are established and calibrated based on the in-house experimental data for finite element (FE) modeling. A novel damage model is proposed to replicate the phenomenon of the stiffness degradation in compression. It is found that accurate predictions on the mechanical responses of PMI foam can be achieved under different temperatures and strain rates. This study is anticipated to provide fundamental experimental data and effective constitutive models of PMI foam for real engineering applications, such as lightweight design of sandwich structures under some harsh conditions.聚甲基丙烯酰亚胺(PMI)泡沫由于其优异的轻量化和优异的机械性能,在工程应用中表现出巨大的潜力。而温度和加载速率对其力学性能影响较大,是实际应用中分析和设计PMI泡沫结构的关键因素。遗憾的是,关于PMI泡沫在不同环境温度和应变速率下的各种应力状态下的弹塑性性能,目前缺乏基础数据和本构模型。因此,本研究旨在通过生成基础实验数据,为PMI泡沫材料和结构提供通用的建模解决方案,填补这一知识空白。为了更好地反映实际使用情况,在不同温度和应变速率下考虑了不同的应力状态。应用循环载荷来表征PMI泡沫的实际力学响应,其中初始和随后的屈服面进行了校准和分析。根据实验结果,深入研究了PMI泡沫材料的弹性、塑性、粘度和损伤特性,特别是初始屈服行为和后续屈服行为。在此基础上,建立了基于热应变率和应变率的本构模型,并基于内部实验数据进行了有限元建模。提出了一种新的损伤模型来模拟压缩时的刚度退化现象。研究发现,在不同温度和应变速率下,PMI泡沫材料的力学响应可以得到准确的预测。本研究有望为实际工程应用提供基础实验数据和有效的PMI泡沫本构模型,如夹层结构在某些恶劣条件下的轻量化设计。Bi-material multistable auxetic honeycombs with reusable and enhanced energy-absorbing phases under in-plane crushingXinwei Wu, Sen Zhang, Liangzhu Ding, Wuqiang Wu, Yongbin Ma, Zichen Dengdoi:10.1016/j.tws.2024.111988面内破碎下可重复利用增强吸能相的双材料多稳定辅助蜂窝The ideal energy absorption structures, in addition to possessing reusability and high energy absorption efficiency, should also possess multiple desired properties to fulfill various functional applications. In this study, a bi-material multistable auxetic honeycomb (BMAH) is fabricated by using bi-material 3D printing technology. Under in-plane crushing, multiple stress plateaus can be achieved and the Poisson's ratio can be stably tuned, allowing for a transition from near-zero to negative and then to positive. The above characteristics are attributed to the specimen's multi-path deformation. The first stress plateau is only associated with recoverable elastic deformation. The second and third stress plateaus, which are 8 times and 17 times higher respectively than the first, are associated with plastic deformation, significantly enhancing energy absorption efficiency. The deformation mechanism is theoretically analyzed, and the effects of geometric parameters on the performance of BMAH are investigated. In addition, the effect of crushing velocity on the crushing behavior of the BMAH is also discussed. As the crushing velocity increases, the total number of stress plateaus transitions from three initially to two and then to one. The developed BMAH exhibits significant potential applications in multi-stage energy absorbers and smart sensors.理想的吸能结构除了具有可重复使用性和高能量吸收效率外,还应具有多种所需的性能,以满足各种功能应用。本研究采用双材料3D打印技术制备了双材料多稳定型消声蜂窝(BMAH)。在平面内破碎时,可以实现多个应力平台,泊松比可以稳定调整,允许从接近零到负,然后再到正的过渡。上述特征与试件的多径变形有关。第一个应力平台只与可恢复的弹性变形有关。第二和第三应力平台与塑性变形相关,显著提高了吸能效率,分别是第一应力平台的8倍和17倍。从理论上分析了BMAH的变形机理,并研究了几何参数对其性能的影响。此外,还讨论了破碎速度对BMAH破碎性能的影响。随着破碎速度的增加,应力高原的总数由最初的3个变为2个,再变为1个。所开发的BMAH在多级能量吸收器和智能传感器方面具有重要的应用潜力。来源:复合材料力学仿真Composites FEM

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