冲击作用下薄壁金属空心球压缩变形研究

DEFORMATION OF METALLIC THIN-WALLED HOLLOW SPHERES UNDER DYNAMIC COMPRESSION

金属空心球结构是一种新型的多孔金属材料,对单个金属空心球在冲击作用下的压缩力学性能研究是对整体结构压缩力学性能研究的基础。该文研究了单个球壳冲击压缩特性,得到了单个金属空心球在冲击作用下的名义应力-应变曲线并与实验结果进行了对比验证,同时研究了径厚比和冲击速度对变形过程的影响。结果表明:名义应力-应变曲线和变形模态图显示其变形失效过程可分成六个阶段:局部压平、轴对称凹陷、多边形形成、内表面相互作用、侧壁失效以及密实阶段;径厚比越大,金属空心球越容易形成非对称的多边形形式,且在内表面相互作用阶段,上部壳体发生逆向翻转,侧壁发生了屈曲失效;径厚比较小时,在内表面相互作用阶段,下部壳体发生逆向翻转,侧壁发生了弯曲失效;冲击速度越大,底端壳开始发生凹陷的时间越早,空心球产生的不对称度越大。

Dynamic compressive behavior of single metallic hollow spheres is fundamental to hollow sphere structures. Based on numerical simulations performed in this study, normalized stress-strain curves of a single metallic hollow sphere were obtained and compared with experimental results. According to the curves and deformation modes, the deformation process was summarized into six stages. The effects of the diameter-to-wall thickness ratio and the impact velocity on the dynamic deformation process were further investigated. It was found that, with an increase in the diameter-to-wall thickness ratio, the failure modes of side walls transformed from bending to buckling and the reverse turnover of internal surfaces transformed from bottom to top. Moreover, as the impact velocity increases, the bottom shell of the hollow sphere dimpled sooner and the deformation asymmetry was much larger.