不同冲击速度下泡沫铝变形和应力的不均匀性

利用常规Hopkinson杆实验装置和改进的Hopkinson杆实验装置对泡沫铝试件进行冲击压缩实验，同时用高速摄影装置对实验过程进行全程跟踪拍摄。通过改变冲击速度，观测到了3种不同的变形模式。将得到的高速摄影图像用数字图像相关方法进行分析，讨论了3种模式下全场应变不同的发展过程，并依此讨论应力的不均匀性，为研究不同冲击速度下变形不均匀对泡沫铝动态力学行为的影响提供了新的方法。

Deformation and stress nonuniformity of aluminum foam under different impact speeds

A split Hopkinson pressure bar apparatus (SHPB) and a modified SHPB apparatus were employed to investigate the dynamic responses of aluminum foam. During the experiments, a high-speed camera was used to record the deformation process of specimens. Three deformation patterns were observed with the increase of the impact speed. All photographs recorded were analyzed by the digital imaging correlation method. The analytical results were used to illustrate the strain field progressing and the stress nonuniformity of these three deformation patterns. And they are helpful in the revealing of the intrinsic mechanisms of these three deformation patterns. This method offers a new and reliable method to study the influence of deformation nonuniformity on dynamic mechanical behaviors of aluminum foam under different impact speeds.