今日更新:International Journal of Solids and Structures 2 篇,Journal of the Mechanics and Physics of Solids 2 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 3 篇
A parametrized continuum constitutive model for reinforced thermoplastic composites with mechanically interlocked interface
Anmol Kothari, Istemi B. Ozsoy, Gang Li
doi:10.1016/j.ijsolstr.2024.112994
具有机械互锁界面的增强热塑性复合材料的参数化连续本构模型
Reinforced thermoplastic composites (RTPC) exhibit weak interfacial strength due to the low surface energy of the polymer matrix. Recently, a concept of controlled mechanical interlocking was introduced that showed significant improvement in the interfacial shear strength with pure mechanical interlocking and no chemical bond/friction. In this paper, a parameterized continuum material model is developed through computational homogenization for an E-glass/polypropylene (PP) composite system with a mechanically interlocked interface. Such parametric models not only elucidate the effects of the microstructural parameters on the mechanical behavior of the material but also enables the optimization of the composite at the microstructure level.
增强热塑性复合材料(RTPC)由于聚合物基体表面能低而表现出较弱的界面强度。最近,一种受控机械联锁的概念被引入,在纯机械联锁而没有化学键/摩擦的情况下,界面抗剪强度得到了显著提高。本文通过计算均质化,建立了具有机械互锁界面的e -玻璃/聚丙烯(PP)复合材料体系的参数化连续材料模型。这些参数化模型不仅阐明了微观结构参数对材料力学行为的影响,而且能够在微观结构水平上对复合材料进行优化。
Constitutive description of distortional hardening in a TWIP steel: Addressing differential hardening under nonlinear strain paths
Kang Wu, Chengchao Fang, Yong Sun, Jun Yang
doi:10.1016/j.ijsolstr.2024.113000
TWIP钢变形硬化的本构描述:处理非线性应变路径下的差异硬化
The present study aims to describe the in-plane differential hardening behaviour of the twinning induced plasticity sheet metal TWIP980 under various stress states, including uniaxial tension, plane strain tension, and pure shear, particularly focusing on non-proportional loading conditions. The true stress–strain curves for each stress states were inversely obtained from their corresponding load–displacement curves and modeled using a differential hardening model that can accommodate all three stress states simultaneously on plastic work (density) contours. For non-proportional loading tests, oversize specimens were initially stretched under uniaxial tension up to a 10% pre-strain along the rolling, diagonal, and transverse directions, respectively. Subsequently, the three stress states were applied to subsize specimens cut from the deformed oversize specimens along the rolling direction. To describe the hardening behaviours during non-proportional loading, a homogeneous anisotropic hardening model was adopted and calibrated using two-step uniaxial tension tests. Subsequently, the differential hardening model was successfully incorporated into the homogeneous anisotropic hardening model to describe both the differential hardening and the strain path change-induced hardening behaviours under the two-step loadings, i.e., uniaxial tension to pure shear and uniaxial tension to plane strain tension. Both experimental and simulation results underscore the necessity to consider differential hardening under non-proportional loading conditions.
本研究旨在描述双晶诱导塑性板材TWIP980在不同应力状态下的面内差异硬化行为,包括单轴拉伸、平面应变拉伸和纯剪切,特别关注非比例加载条件。每个应力状态下的真实应力-应变曲线由其对应的载荷-位移曲线反向获得,并使用微分硬化模型建模,该模型可以同时在塑性工作(密度)轮廓上容纳所有三种应力状态。对于非比例加载试验,超大试件在单轴拉伸下分别沿滚动、对角线和横向拉伸至10%的预应变。随后,将这三种应力状态应用于从变形的超大尺寸试样上沿轧制方向切割的亚尺寸试样。为了描述非比例加载时的硬化行为,采用均匀各向异性硬化模型,并采用两步单轴拉伸试验进行校准。随后,将差异硬化模型成功地纳入均匀各向异性硬化模型,以描述单轴拉伸到纯剪切和单轴拉伸到平面应变拉伸两步加载下的差异硬化和应变路径变化引起的硬化行为。实验和模拟结果都强调了在非比例加载条件下考虑差异硬化的必要性。
The adjustable adhesion strength of multiferroic composite materials via electromagnetic loadings and shape effect of punch
Qing-Hui Luo, Yue-Ting Zhou, Yuxiao Yang, Shenghu Ding, Lihua Wang
doi:10.1016/j.jmps.2024.105794
利用电磁载荷和冲头形状效应调节多铁复合材料的粘接强度
Tunable and reversible dry adhesion possess great potential in a wide range of applications including transfer printing, climbing robots, wearable devices/electronics, and gripping in pick-and-place operations. Multiferroic composite materials offer new routines and approaches to achieve tunable adhesion due to their multi-field coupling effects. In this paper, the classical Johnson-Kendall-Roberts (JKR) adhesion model is extended to investigate the adhesive contact problem of a multiferroic composite half-space indented by an axisymmetric power-law shaped punch, whose shape index is denoted by n. The JKR-n adhesion models under the action of the power-law shaped punches with four different electromagnetic properties are set up by means of the total energy method. The explicit analytical expressions relating the indentation load and indentation depth to the contact radius are obtained, which can include the existing results in open literature as special cases. The generalized Tabor parameter and the interfacial adhesion strength applicable to multiferroic composite materials are defined. The effects of the shape index and the electromagnetic loadings on adhesion behaviors are revealed. It is found that both of them have prominent influences on the relationships among the indentation load, indentation depth and contact radius, the contact radius and indentation depth at self-equilibrium state, and the critical contact radius and indentation depth at pull-off moment. The pull-off force under the action of the conducting spherical punch subjected to non-zero electromagnetic loadings is dependent on material properties, which is different from the classical JKR result. More importantly, our analysis indicates that the pull-off force and the interfacial adhesion strength can be adjusted via altering the electromagnetic loadings and the shape index of the punch, which provides new approaches to achieve tunable adhesion.
可调和可逆的干粘附在广泛的应用中具有巨大的潜力,包括转移印刷,攀爬机器人,可穿戴设备/电子产品,以及在拾取和放置操作中的抓取。多铁复合材料由于其多场耦合效应,为实现可调粘附提供了新的思路和方法。本文将经典的Johnson-Kendall-Roberts (JKR)粘接模型推广到研究形状指数为n的轴对称幂律型冲头压痕下多铁复合材料半空间的粘接接触问题。利用总能量法建立了四种不同电磁性能幂律型冲头作用下的JKR-n粘接模型。得到了压痕载荷和压痕深度与接触半径的显式解析表达式,作为特例可以包括公开文献中已有的结果。定义了适用于多铁复合材料的广义Tabor参数和界面粘接强度。揭示了形状指数和电磁载荷对粘接性能的影响。发现两者对压痕载荷、压痕深度与接触半径、自平衡状态下的接触半径与压痕深度、拉脱时刻临界接触半径与压痕深度之间的关系有显著影响。在非零电磁载荷作用下,导电球冲头的拉脱力取决于材料的性质,这与经典的JKR结果不同。更重要的是,我们的分析表明,拉拔力和界面粘附强度可以通过改变电磁载荷和冲头的形状指标来调节,这为实现可调粘附提供了新的途径。
Pressurized membranes between walls: Thermodynamic process changes force and stiffness
Paul Lacorre, Louison Fiore, Jean-Marc Linares, Loïc Tadrist
doi:10.1016/j.jmps.2024.105798
壁间加压膜:热力学过程改变了力和刚度
Pressurized solids are ubiquitous in nature. Mechanical properties of biological tissues arise from cell turgor pressure and membrane elasticity. Flat contact between cells generate nonlinear forces. In this work, cells are idealized as pressurized elastic membranes in frictionless contact with one another. Contact forces are experimentally measured on rubber-like membranes and computed using finite element analysis (FEA). FEA matches experimental force-indentation relationships from small to large indentations. With the chosen dimensionless numbers, data gather on a master curve. The isobaric force exhibits a 4/3 power law over 1.5 decades of indentation. Forces for other thermodynamic processes (adiabatic, isothermal/osmotic and isochoric) are interpolated from isobaric data. Regarding stiffness, the isochoric process is superlinear contrary to the sublinear isobaric stiffness. Simple force-indentation relationships are given for each process.
加压固体在自然界中无处不在。生物组织的力学特性是由细胞的膨胀压力和膜的弹性决定的。单元间的平面接触产生非线性力。在这项工作中,细胞被理想化为彼此无摩擦接触的加压弹性膜。实验测量了类橡胶膜上的接触力,并用有限元法计算了接触力。有限元分析从小到大的压痕匹配实验力-压痕关系。有了选定的无量纲数,数据就会在一条主曲线上收集。等压力在15年的压痕中呈现4/3幂律。其他热力学过程(绝热、等温/渗透和等时)的力由等压数据插值。在刚度方面,等压过程与次线性等压刚度相反是超线性的。给出了每个过程的简单力-压痕关系。
Carbon nanotubes as a basis of metamaterials and nanostructures: Crafting via design optimization
Marko Čanađija, Stefan Ivić
doi:10.1016/j.mechmat.2024.105105
碳纳米管作为超材料和纳米结构的基础:通过设计优化制作
Nanotruss structures made of carbon nanotubes are investigated in two conceptual applications: either as building blocks of metamaterials or for nanostructural applications. The nanotrusses are optimized for different purposes, including various loadings, boundary conditions, parameterizations, objectives and constraints used to formulate optimization problems. The procedure relies on a recently developed framework consisting of molecular dynamics simulations, neural networks and finite elements. This framework is now used in the design optimization of nanostructures and the performances of different popular heuristic optimization methods are compared. Five applications of nanotrusses made of carbon nanotubes are analyzed in detail to investigate the mechanical behavior of such structures and the efficiency of the optimizations. Besides an introductory example, the design of an energy trapping carbon nanotube nanotruss, an auxetic nanotruss, a cantilever nanotruss and the maximization of the compressive strength of a metamaterial are presented. It is shown that the exceptional mechanical properties of carbon nanotubes can indeed be exploited for the development of structures and materials with extraordinary mechanical properties. Although hampered by material and geometrical nonlinearity of the problem, most of the tested optimization methods have proven to be a good choice for the design of such materials and structures.
由碳纳米管制成的纳米桁架结构在两个概念上的应用:作为超材料的构建块或用于纳米结构应用。纳米桁架针对不同的目的进行了优化,包括各种负载、边界条件、参数化、目标和约束,用于制定优化问题。该程序依赖于最近开发的由分子动力学模拟、神经网络和有限元组成的框架。该框架目前已用于纳米结构的设计优化,并比较了不同流行的启发式优化方法的性能。详细分析了碳纳米管纳米桁架的五种应用,研究了这种结构的力学性能和优化的效率。此外,还介绍了能量捕获型碳纳米管纳米桁架、辅助型纳米桁架、悬臂型纳米桁架以及超材料抗压强度最大化的设计方法。研究结果表明,碳纳米管优异的力学性能确实可以用于开发具有优异力学性能的结构和材料。虽然受到材料和几何非线性问题的限制,但大多数经过试验的优化方法已被证明是这类材料和结构设计的良好选择。
Behaviour, finite element modelling and design of flanged cruciform section steel columns
Ruikai Dai, Behnam Behzadi-Sofiani, Spiridione Buhagiar, M. Ahmer Wadee, Leroy Gardner
doi:10.1016/j.tws.2024.112268
法兰十字截面钢柱的性能、有限元建模与设计
A study into the mechanical behaviour and design of flanged cruciform section steel members subjected to axial compression is presented herein. The mechanical behaviour of flanged cruciform section columns is first described, with particular emphasis on the newly developed approach for determining the elastic local buckling load for full flanged cruciform cross-sections. Existing experimental data on flanged cruciform section steel columns collected from the literature are then employed to validate numerical models developed within the finite element package ABAQUS. A comprehensive parametric study is subsequently conducted that encompasses a broad spectrum of cross-sectional geometries and global slenderness values. The mechanical behaviour and ultimate resistance of flanged cruciform section columns are shown to be dependent on not only the global slenderness, but also on the ratio of the elastic torsional to flexural buckling loads. The existing experimental data alongside the numerical parametric study results are employed to evaluate the resistance predictions provided in the current Eurocode 3 design codes, revealing a high level of conservatism. Finally, a new design approach for flanged cruciform section columns, suitable for incorporation into future revisions of Eurocode 3, is proposed which provides significantly improved accuracy and consistency in resistance predictions compared with the current provisions. A reliability analysis of the proposed design approach is conducted in accordance with the EN 1990 procedure, resulting in a recommended partial safety factor γ M1 = 1 . 0 .
本文研究了十字形法兰型钢构件在轴压作用下的受力性能及设计。首先描述了法兰十字形截面柱的力学行为,特别强调了确定全法兰十字形截面弹性局部屈曲载荷的新方法。从文献中收集的法兰十字形截面钢柱的现有实验数据,然后用于验证在有限元软件包ABAQUS中开发的数值模型。随后进行了全面的参数化研究,包括广泛的横截面几何形状和整体长细比值。结果表明,法兰十字形截面柱的力学性能和极限抗力不仅与整体长细比有关,而且与弹性扭转载荷与弯曲屈曲载荷的比值有关。利用现有的实验数据和数值参数研究结果对现行欧洲规范3设计规范中提供的阻力预测进行了评估,显示出高度的保守性。最后,提出了一种新的法兰十字形截面柱的设计方法,适合纳入欧洲规范3的未来修订,与现行规定相比,该方法在阻力预测方面提供了显着提高的准确性和一致性。根据en1990程序对建议的设计方法进行可靠性分析,得出建议的部分安全系数γ M1 = 1。0。
Flexible Roll Forming of surface developable profiles from Dual Phase steel.
Achuth Sreenivas, Buddhika Abeyrathna, Bernard Rolfe, Matthias Weiss
doi:10.1016/j.tws.2024.112271
双相钢表面可展型材的柔性辊压成形。
Flexible Roll Forming (FRF) can roll-form variable cross-sectional profiles for Electric Vehicle (EV) production however, a major limitation exists due to flange wrinkling while forming high-strength steels. Flange wrinkling can be eliminated by reducing the required level of membrane deformation in the longitudinal direction. Although reducing the severity of the profile's transitions minimises the strains, the overall complexity of the parts is also lowered. Origami-based developable profiles can be created from curved creased folding without membrane stretching or compression. In FRF, such types of profiles can be formed by combining a variation in width and depth over the length of the part. This study presents, for the first time, the analyses of forming a developable shape in a FRF operation. Firstly, analytical equations are applied to calculate the strains and forming stability of each pass which is followed by experimental FRF trials on two high-strength Dual Phase steels. Finally, Finite Element Analysis is used to investigate the forming behaviour of the two types of developable profiles. The experimental results show that the forming of one type of developable profile improves the shape, while the numerical analyses showed that an additional top-hat forming is required for the second profile type.
柔性辊压成形(FRF)可以轧制出电动汽车(EV)生产的可变截面型材,但在成形高强度钢时存在法兰起皱的主要限制。可以通过降低纵向所需的膜变形水平来消除法兰起皱。虽然降低了型材过渡的严重程度,最大限度地减少了应变,但零件的整体复杂性也降低了。折纸为基础的可展轮廓可以创建从弯曲折痕折叠膜拉伸或压缩。在频响中,这种类型的轮廓可以通过结合零件长度上的宽度和深度变化来形成。本研究首次提出了在频响操作中形成可展开形状的分析。首先用解析方程计算了各道次的应变和成形稳定性,然后对两种高强度双相钢进行了频响试验。最后,采用有限元分析方法研究了两种可展开型材的成形行为。实验结果表明,一种可展开轮廓的成形可以改善形状,而数值分析表明,第二种轮廓需要额外的顶帽成形。
Metamaterial design enabling simultaneous manipulation of Rayleigh and Love waves
Jia Lou, Hui Fan, Jie Yang, Menghui Xu, Jianke Du
doi:10.1016/j.tws.2024.112273
可以同时操纵瑞利波和洛夫波的超材料设计
Studies on elastic metamaterials have expanded from manipulating bulk waves to surface waves, aiming to control the propagation of in-plane Rayleigh waves or anti-plane Love waves. Considering the coexistence of Rayleigh and Love waves in various scenarios, the objective of this study is to develop a metamaterial capable of simultaneously manipulating both types of waves. The proposed metamaterial consists of horizontal resonators with an oblique mounting angle relative to the wave propagation direction, as well as vertical resonators. Initially, analytical solutions for the dispersion of surface waves are derived, followed by Finite Element (FE) simulations to validate the analytically predicted dispersion and illustrate the corresponding wave modes, as well as the in-plane and out-of-plane displacement fields at specified frequencies. The present study reveals that the mounting angle of the horizontal resonators plays a crucial role in surface wave manipulation. By adjusting the mounting angle, three distinct objectives can be achieved: i) the attenuation of Rayleigh waves alone; ii) the independent attenuation of Rayleigh and Love waves, targeting different frequency ranges; and iii) the simultaneous attenuation of both Rayleigh and Love waves.
弹性超材料的研究已经从控制体波扩展到控制面波,目的是控制面内瑞利波或反面洛夫波的传播。考虑到瑞利波和洛夫波在各种情况下的共存,本研究的目标是开发一种能够同时操纵两种波的超材料。所提出的超材料包括相对于波传播方向具有倾斜安装角的水平谐振器以及垂直谐振器。首先推导了表面波色散的解析解,然后进行了有限元模拟,验证了解析预测的色散,并说明了相应的波模,以及在指定频率下的面内和面外位移场。研究表明,水平谐振器的安装角度对表面波控制起着至关重要的作用。通过调整安装角度,可以实现三个不同的目标:1)瑞利波的单独衰减;ii)针对不同频率范围的瑞利波和洛夫波的独立衰减;瑞利波和洛夫波同时衰减。