爆炸加载柱壳剪切断裂演化过程主控应力机制研究

爆炸载荷作用下金属柱壳的剪切型断裂的发生及单旋破坏现象受到载荷、材料、结构几何及尺寸特征等诸多因素影响，引起广泛关注。本申请拟对爆轰加载下金属柱壳中单旋型剪切断裂的萌生、裂纹传播、以及剪切裂纹贯穿后柱壳的滑移碎裂过程进行分析，获得柱壳特征应力分布随其膨胀/压缩进程的变化关系。结合实验，对作为剪切裂纹前驱的多重绝热剪切带的生成和演化、剪切带发展为剪切裂纹、多重剪切裂纹的扩展和演化等的物理条件进行识别；结合二维或三维数值分析，对爆炸加载下柱壳剪切断裂过程的各个阶段进行划分和定义，提出柱壳变形过程中描述剪切带（或裂纹）的行为以及剪切带（或裂纹）附近局部卸载区应力场的物理限制条件或模型建议。本研究对于金属柱壳破坏规律理解、结构的可靠设计与理论分析具有重要意义。

The fracture properties of the shells have been studied by many researchers in the recent years. The onset and evolutions of the self-organized shear fractures of metal cylindrical shells under explosive loadings are affected by many factors such as the characteristics of the impulsive loadings, the dynamic behavior of the materials, the geometry of the shell structures, etc. In this proposal, the crack initiations and propragations of the self-organized shear fractures which occur in cylindrical metal shells driven by either explosive or implosive loadings will be studied. The characteristics of the stress state of the cylindrical metal shell, which varies with the developing of the shear deformation and fracture, will also be investigated. Experimental research will be conducted to help distinguish the shear fracture process of the shells, which may be divided into three stages: 1) the initiations and evolutions of multiple-adiabatic shear bands, 2) the onset of shear crackings from shear bands, and 3) the growth and propagations of the multiple shear cracks that cause the ultimate break-up of the shell. Furthermore, stress analysis will be conducted to understand the unloading process of zones neighboring the multiple shear bands (or cracks). This analysis, combined with the 2-dimensional or 3-dimensional numerical-simulations, will identify the transition criteria of the shear deformation/localization/failure stages of the shells under explosive loadings., The research on one hand will significantly improve the understanding of the fracture and fragmentation behavior of the explosively loaded cylindrical metal shell, on the other hand, it will help for the design and the evaluation of protecting structures against explosive loadings.