恒定高应变率拉伸条件下泡沫金属力学性能

为了探究泡沫金属恒定应变率动态拉伸力学行为，基于3D Voronoi模型，采用双向拉伸加载方式和1.55倍等效胞孔直径高度的试件，实现了5000 s⁻¹恒定高应变率动态拉伸条件下泡沫金属力学性能测试数值模拟实验，模拟结果显示：动态拉伸过程满足应力均匀性和变形均匀性要求，且试件破坏位置合理；在恒定应变率（0.5～5000 s⁻¹）动态拉伸时，泡沫金属的破坏应变基本不受应变率的影响；当应变率不超过500 s⁻¹ 时，破坏应力受应变率影响很小，当应变率在 500～5000 s⁻¹ 时，破坏应力随着加载速率的增大而线性增大。

Mechanical property of metallic foams under dynamic tension with constant high strain rate

In order to explore the dynamic behavior of metallic foams under the stretch of constant high strian rate, a few numerical simulations were conducted to explore the effects of both the height of specimen and the tensile velocity on the stress uniformity and deformation uniformity as well as the failure position of the specimen under dynamic tensile loading. And then, a feasible numerical simulation scheme was proposed to obtain dynamic tensile properties of metallic foams under dynamic tension loading with constant strain rates. According to this scheme, the max strain rate reaches 5000 s−1 by means of both decreasing the height of specimen to 1.55 times of the cells’ equivalent diameter and stretching the specimen in two opposite directions with the same velocity. The scheme was verified to be rational by these four main requirements: the stress uniformity and deformation uniformity of the specimen, the acceptable failure position of the specimen and good repeatability. Employing this scheme, a series of dynamic tensile simulations were carried out to investigate the effect of the strain rate on the dynamic tensile mechanical properties of metallic foams. Results show that the failure strain of metallic foams is almost independent of the strain rate in the range from 0.5 s−1 to 5000 s−1, and the failure stress of metallic foams is slightly affected by strain rate in the range from 0.5 s−1 to 500 s−1, but increases linearly with the strain rate in the range from 500 s−1 to 5000 s−1.