今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 2 篇,Thin-Walled Structures 1 篇
Correlation between surface-to-volume ratio of the particle shape and elastic properties of the particulate composites
Pascal Alexander Happ, Romana Piat
doi:10.1016/j.ijsolstr.2024.112658
颗粒形状的表面体积比与颗粒复合材料弹性特性之间的相关性
This work is motivated by real-world particle shapes, observed using a scanning electron microscopy. The focus of the presented studies was to understand the effects of the particle shapes on the effective elastic properties of the two-phase composites. For this, particles with polyhedral, undulated and other shapes were numerically modeled using analytical functions. Creation of some shapes, like polyhedral, are known from the literature but Laplace’s spherical harmonics, as well as the Goursat’s surface and some others, were used for the first time to create novel particle shapes. Elastic properties of the composites with different particle shapes were calculated using the finite element analysis. The obtained results show good agreement with mean-field homogenization methods such like Mori-Tanaka and Lielens as well as other numerical results available in the literature. Further, the dependence of the effective Young’s moduli of the composite on the shape and the corresponding surface-to-volume ratio of the particles was studied. It was observed that the effective Young’s moduli increase with the surface-to-volume ratio of the particles in the case where particles are stiffer in comparison to the matrix. It was also remarked that, in the case of particles of similar shapes, the particle surface-to-volume ratio and the effective Young’s moduli differ significantly with the surface curvature and the edge sharpness of the particles.
这项工作的动力来自于使用扫描电子显微镜观察到的真实颗粒形状。本研究的重点是了解颗粒形状对两相复合材料有效弹性特性的影响。为此,使用分析函数对多面体、波状和其他形状的颗粒进行了数值建模。一些形状(如多面体)的创建已从文献中获知,但拉普拉斯球面谐波以及 Goursat 曲面和其他一些形状是首次用于创建新颖的颗粒形状。使用有限元分析计算了不同颗粒形状的复合材料的弹性特性。所得结果与 Mori-Tanaka 和 Lielens 等平均场均质化方法以及文献中的其他数值结果显示出良好的一致性。此外,还研究了复合材料的有效杨氏模量与颗粒形状和相应的表面体积比的关系。研究发现,在颗粒与基体相比更硬的情况下,有效杨氏模量随颗粒的表面体积比增加而增加。研究还注意到,在颗粒形状相似的情况下,颗粒表面体积比和有效杨氏模量随颗粒表面曲率和边缘锐度的变化而显著不同。
Grain boundary network plasticity: Reduced-order modeling of deformation-driven shear-coupled microstructure evolution
Daniel Bugas, Brandon Runnels
doi:10.1016/j.jmps.2024.105541
晶界网络塑性:变形驱动剪切耦合微结构演化的降阶建模
Microstructural evolution in structural materials is known to occur in response to mechanical loading and can often accommodate substantial plastic deformation through the coupled motion of grain boundaries (GBs). This can produce desirable behavior, such as increased ductility, or undesirable behavior such as mechanically-induced coarsening. In this work a novel, multiscale model is developed for capturing the combined effect of plasticity mediated by multiple GBs simultaneously. This model is referred to as “grain boundary network plasticity.” The mathematical framework of graph theory is used to describe the microstructure connectedness, and the evolution of microstructure is represented as volume flow along the graph. By using the principle of minimum dissipation potential, which has previously been applied to grain boundary migration, a set of evolution equations are developed that transfer volume and eigendeformation along the graph edges in a physically consistent way. It is shown that higher-order geometric effects, such as the pinning effect of triple points, may be accounted for through the incorporation of a geometric hardening that causes geometry-induced GB stagnation. The result is a computationally efficient reduced order model that can be used to simulate the initial motion of grain boundaries in a polycrystal with parameters informed by atomistic simulations. The effectiveness of the model is demonstrated through comparison to multiple bicrystal atomistic simulations, as well as a select number of GB engineered and non-GB engineered data obtained from the literature. The effect of the network of shear-coupling grain boundaries is demonstrated through mechanical response tests and by examining the yield surfaces.
众所周知,结构材料的微观结构演变是对机械负载的响应,通常可通过晶界(GB)的耦合运动产生大量塑性变形。这可能产生理想的行为,如增加延展性,也可能产生不理想的行为,如机械引起的粗化。本研究开发了一种新型多尺度模型,可同时捕捉多个 GB 介导的塑性综合效应。该模型被称为 "晶界网络塑性"。该模型采用图论的数学框架来描述微观结构的连通性,并将微观结构的演变表示为沿图的体积流。利用之前应用于晶界迁移的最小耗散势原理,建立了一组演化方程,以物理一致的方式沿图边传递体积和特征变形。研究表明,高阶几何效应(如三重点的针销效应)可以通过加入几何硬化来解释,几何硬化会导致几何诱导的 GB 停滞。结果是一个计算效率高的降阶模型,可用于模拟多晶体中晶界的初始运动,其参数由原子模拟提供。通过与多个双晶原子模拟以及从文献中获取的部分 GB 工程和非 GB 工程数据进行比较,证明了该模型的有效性。通过机械响应测试和屈服面检查,证明了剪切耦合晶界网络的效果。
Constitutive models for confined elastomeric layers: Effects of nonlinearity and compressibility
Sida Hao, Rui Huang, Gregory J. Rodin
doi:10.1016/j.mechmat.2024.104912
约束弹性层的构造模型:非线性和可压缩性的影响
Elastomers tend to undergo large deformations accompanied by small volumetric changes. For elastomeric layers sandwiched between rigid plates, large deformations can be significantly limited by the constraints imposed by the plates. Further, those constraints can be enhanced by material’s inability to undergo large volumetric changes. From this perspective, it is appropriate to examine the validity of constitutive models, in which an elastomer is treated as incompressible, for analysis of the confined layers. Here, this issue is addressed by considering the mechanical response of sandwiched elastomeric layers using three constitutive models. The first one, referred to as compressible neo-Hookean, is regarded as exact. The other two models are regarded as approximations. Of those two, the first one neglects nonlinearity and the second one neglects compressibility. Accordingly, the modeling errors associated with the former are treated as measures of importance of nonlinearity, and the modeling errors associated with the latter are treated as measures of importance of compressibility. The modeling errors are evaluated using the force–displacement curve and the mean stress at the layer center as the quantities of interest. Numerical results are presented for rubber and polydimethylsiloxane (PDMS), characterized by Poisson’s ratios ν=0.4999 and ν=0.49, respectively. It is shown that, even when the forces applied to the plates are large, considering nonlinearity is important for thick but not for thin layers. In contrast, considering compressibility is important for thin layers. The need for considering compressibility is further assessed by introducing a competition parameter, which reinforces the notion that compressibility is important for modeling PDMS layers and thin rubber layers.
弹性体往往会发生较大的变形,同时伴随着较小的体积变化。对于夹在刚性板之间的弹性层来说,大变形可能会受到刚性板的严重限制。此外,由于材料无法发生大的体积变化,这些限制也会增强。从这一角度出发,研究将弹性体视为不可压缩的构成模型对分析约束层的有效性是合适的。在此,通过使用三种构成模型来考虑夹层弹性体层的机械响应,从而解决这一问题。第一个模型被称为可压缩新胡肯模型,是精确模型。其他两个模型被视为近似模型。在这两个模型中,第一个忽略了非线性,第二个忽略了可压缩性。因此,与前者相关的建模误差被视为非线性重要性的度量,与后者相关的建模误差被视为压缩性重要性的度量。使用力-位移曲线和层中心的平均应力作为相关量来评估建模误差。研究给出了橡胶和聚二甲基硅氧烷(PDMS)的数值结果,这两种材料的泊松比分别为 ν=0.4999 和 ν=0.49。结果表明,即使施加在板上的力很大,考虑非线性对厚层也很重要,但对薄层却不重要。相反,考虑可压缩性对薄层很重要。通过引入竞争参数,进一步评估了考虑可压缩性的必要性,从而加强了可压缩性对于 PDMS 层和薄橡胶层建模非常重要的观点。
A continuum damage coupled unified viscoplastic model for simulating the mechanical behaviour of a ductile cast iron under isothermal low-cycle fatigue, fatigue-creep and creep loading
Michal Bartošák, Jakub Horváth
doi:10.1016/j.ijplas.2023.103868
用于模拟球墨铸铁在等温低循环疲劳、疲劳-蠕变和蠕变载荷下机械性能的连续损伤耦合统一粘塑模型
A novel continuum damage coupled unified viscoplastic model is used for simulating the stress–strain responses of SiMo 4.06 cast iron under Low-Cycle Fatigue (LCF), fatigue-creep and creep loading for temperatures up to 650 °C. The advanced constitutive model that is developed within the framework of the Chaboche model allows the simulation of various effects including strain rate sensitivity, cyclic hardening and softening, static recovery and strain range dependency. The hyperbolic sine flow rule and the static recovery of kinematic hardening rule are proposed in order to effectively simulate both stress relaxation and creep strains. The isotropic damage variable is introduced into the constitutive equations to represent the effects of material degradation. Three main damage mechanisms are considered: fatigue, creep and ductile damage. In addition, the model is further modified to take into account the progressive microdefects closure effect. Finally, the prediction capability of the proposed model is illustrated for the experimental data obtained from the various uniaxial material tests. A good correlation was achieved between the simulated and the experimental results.
采用新颖的连续损伤耦合统一粘塑模型模拟 SiMo 4.06 铸铁在低循环疲劳 (LCF)、疲劳-蠕变和蠕变载荷下的应力-应变响应,温度最高可达 650 °C。在 Chaboche 模型框架内开发的高级构成模型可模拟各种效应,包括应变速率敏感性、循环硬化和软化、静态恢复和应变范围依赖性。为了有效模拟应力松弛和蠕变应变,提出了双曲正弦流动规则和运动硬化静态恢复规则。在构成方程中引入了各向同性损伤变量,以表示材料退化的影响。模型考虑了三种主要损伤机制:疲劳损伤、蠕变损伤和韧性损伤。此外,还进一步修改了模型,以考虑渐进式微缺陷闭合效应。最后,针对从各种单轴材料试验中获得的实验数据,说明了所提模型的预测能力。模拟结果和实验结果之间实现了良好的相关性。
A computational mechanical constitutive modeling method based on thermally-activated microstructural evolution and strengthening mechanisms
Mingyu Lei, Guangpeng Sun, Guochun Yang, Bin Wen
doi:10.1016/j.ijplas.2024.103881
基于热激活微结构演化和强化机制的计算力学结构建模方法
A mechanical constitutive relationship is the basis for the design and application of structural materials, and the establishment of a mechanical constitutive relationship generally relies on experimental data. Herein a computational mechanical constitutive modeling method is proposed, in which all required parameters possess unambiguous physical interpretations and/or can be obtained from accurate numerical simulations. With the inclusion of interaction between dislocations and crystal defects, the dislocation density and grain size evolution with strain for polycrystalline metallic materials are mathematically modeled, and the corresponding contribution to strength is analysed, further a computational mechanical constitutive relationship can be obtained. Its effectiveness is verified by comparing it with experimental stress-strain relationships for Cu, Al-Mg, and Cu-W alloys. This method might be a powerful tool for the design of structural materials with desirable mechanical properties.
力学构成关系是结构材料设计和应用的基础,而力学构成关系的建立一般依赖于实验数据。本文提出了一种计算力学构成模型方法,其中所有必要参数都具有明确的物理解释和/或可从精确的数值模拟中获得。通过将位错与晶体缺陷之间的相互作用考虑在内,对多晶金属材料的位错密度和晶粒大小随应变的演变进行了数学建模,并分析了其对强度的相应贡献,从而进一步获得了计算力学组成关系。通过与铜、铝-镁和铜-钨合金的实验应力-应变关系进行比较,验证了该方法的有效性。这种方法可能是设计具有理想机械性能的结构材料的有力工具。
Deformation behaviors of defective aluminum honeycomb sandwich panels subjected to in-panel compressive loading: an experimental study with mirror-assisted multi-view DIC
Kaiyu Zhu, Bing Pan
doi:10.1016/j.tws.2024.111592
缺陷铝蜂窝夹芯板在板内压缩载荷作用下的变形行为:利用镜像辅助多视角 DIC 进行的实验研究
Honeycomb sandwich panels have been extensively utilized in the aerospace and automotive industries for their prominent advantages of energy absorption, high strength and tailorable anisotropic mechanical properties. Nevertheless, the common presence of local core-to-skin disbonding poses an urgent need to understand the mechanical behaviors of defective honeycomb sandwich panels. The present work investigates the deformation behaviors and evolutions of aluminum honeycomb sandwich panels with varying sizes of circular artificial core-to-skin disbonding defects using mirror-assisted multi-view digital image correlation (MV-DIC). Based on the 3D profiles and dual-surface deformation fields obtained with mirror-assisted MV-DIC, it is revealed that disbonding defects induced local surface undulations with severe local strain concentrations and determined the mode of gradual bending and buckling. Defects with a diameter below 20 mm induced minor local surface undulations and slight decreases in buckling load. When the diameters of defects reach 30 mm, extensive surface convex deformation occurs and the buckling load decreases by 23%. The results validate mirror-assisted MV-DIC as a cost-effective and practical technique for characterizing dual-surface 3D deformation of sheet composite materials and structures.
蜂窝夹芯板具有能量吸收、高强度和可定制的各向异性机械性能等突出优势,已被广泛应用于航空航天和汽车行业。然而,由于普遍存在局部芯-皮脱粘现象,因此迫切需要了解有缺陷的蜂窝夹芯板的机械性能。本研究利用镜像辅助多视角数字图像相关(MV-DIC)技术,研究了存在不同大小的圆形人工芯-皮脱粘缺陷的铝蜂窝夹芯板的变形行为和演变过程。根据镜像辅助 MV-DIC 所获得的三维剖面和双表面变形场,可以发现脱粘缺陷会引起局部表面起伏,造成严重的局部应变集中,并决定了逐渐弯曲和屈曲的模式。直径小于 20 毫米的缺陷引起的局部表面起伏较小,屈曲载荷也略有下降。当缺陷直径达到 30 毫米时,会出现大面积的表面凹凸变形,屈曲载荷降低了 23%。这些结果验证了镜像辅助 MV-DIC 是表征片状复合材料和结构双表面三维变形的一种经济实用的技术。