爆炸与电磁加载下无氧铜环、柱壳的断裂模式转变

考虑断面收缩率、局域断裂应变以及平均断裂应变，并基于电磁膨胀环、爆炸膨胀环(柱壳)实验平台，研究了高纯无氧铜(TU1)环及柱壳在高应变率载荷下的膨胀断裂行为。采用高速摄影技术拍摄柱壳外壁的膨胀断裂形貌演化过程，用于确定柱壳平均断裂应变；利用激光干涉测速技术获得样品径向膨胀速度历史，用于确定加载应变率；利用样品的全回收测量及微观表征，确定了无氧铜环、柱壳的局域断裂应变及断裂模式。实验表明，随着应变率的增加，TU1材料的平均断裂应变增加，断面的收缩程度加剧，并在应变率约为1.0×104 s-1附近会出现明显的断裂模式转变，断面收缩率出现量级上的跳跃，从100变化至约103，局域断裂应变呈现明显的分区现象。

Fracture mode transition in expanding ring and cylindrical shell under electromagnetic and explosive loadings

In the present study, we designed the electromagnetic and explosive driving expanding ring/cylinder experiments and investigated the expanding fracture characteristics of oxygen-free high-conductivity copper (OFHC) in consideration of the conception of the reduction of area, the local fracture strain and the average fracture strain. We used a high speed camera to record the fracture process and obtain the fracture strain of the copper cylinder and the Doppler pins system (DPS) to obtain the radial velocity of the specimen in order to achieve the strain rate of the loading. We verified the local fracture strain and the fracture mode by analyzing the soft-recovered fragments of the expanding ring and the cylinder. Based on the experimental results, we found that the average fracture strain and the reduction of the area increases as does the strain rate. Moreover, the fracture mode transition may occur at the strain rate of about 1.0×104 s-1, and the reduction of the area may increase by an order of magnitude, i.e. from the order of 100 to that of 103, and the local fracture strain exhibits an obvious subarea.