Characterization of micro- to macroscopic response of polymers containing voids under macroscopically uniform deformation
Characterization of micro- to macroscopic response of polymers containing voids under macroscopically uniform deformation
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DOI：
10.1016/s0020-7683(02)00163-4
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发表时间：
2002-06
影响因子：
3.6
通讯作者：
Y. Tomita;W. Lu
中科院分区：
文献类型：
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作者：
Y. Tomita;W. Lu
为了表征含空隙（空穴橡胶颗粒）的聚合物的力学特性，提出了一种均匀化方法，该方法可以处理大变形问题，包括不稳定性的发生和传播，并且可以再现具有周期性分布空隙的聚合物在宏观非均匀载荷条件下的微观到宏观变形行为。一个参数的研究已经澄清了聚合物的特性功能，包含周期性分布的非均匀的圆柱形空隙的不同体积分数进行宏观均匀的应力在不同的方向。观察到不同类型的剪切带，这取决于相对于晶胞的拉伸方向。连接在变形早期出现的空洞的剪切带是宏观屈服的原因。增加空隙的体积分数导致宏观屈服应力的降低和宏观应力-应变关系的方向依赖性。孔隙的中等不均匀性导致了复杂的不同类型的剪切带;然而，由于小孔隙的存在引起的高应力集中，促进了剪切带的发生和扩展，并且宏观应力-应变关系变得基本上各向同性。然而，单胞的体积应变变化的体积分数和不均匀性的空洞和拉伸方向。
For the characterization of mechanical characteristics of polymers containing voids (cavitated rubbery particles), a homogenization method has been developed, which can handle large deformation problems including the onset and propagation of instability and can reproduce the micro- to macroscopic deformation behavior of polymers with periodically distributed voids under macroscopically inhomogeneous loading conditions. A parametric study has clarified the characteristic features of polymers containing periodically distributed heterogeneous cylindrical voids of different volume fractions subjected to macroscopically homogeneous stress in different directions. Different types of shear bands are observed, depending on the tensile direction with respect to the unit cell. The shear band connecting the voids that appear in the early stages of deformation is responsible for the macroscopic yielding. Increasing the volume fraction of the voids results in a decrease in the macroscopic yield stress and in the directional dependence of the macroscopic stress–strain relationship. The moderate heterogeneity of voids causes complicated and different types of shear bands; however, due to the high stress concentration caused by the presence of small voids, the onset and propagation of the shear bands are promoted, and the macroscopic stress–strain relationships become essentially isotropic. Nevertheless, the volumetric strain of unit cell changes with volume fraction and heterogeneity of the voids and tension directions.