冲击波作用下多孔材料内的温度斑图动力学

Temperature pattern dynamics in shocked porous material1

强冲击作用过程中多孔材料内物理特征量(温度、密度、粒子速度、各种应力等)的分布极其复杂.使用颗粒接触物质点方法对这类过程进行模拟,对材料内复杂的温度场进行形态学分析,引入"结构相似"和"过程相似"的概念,对不同温度阈值条件下的特征结构极其演化过程进行比较研究.发现:在同一材料中,如果冲击强度和温度阈值选取合适,那么高温区域及其演化过程会表现出极其相似的特征.当孔隙度较高时,过程相似要求的温度阈值和冲击速度成二次抛物线关系;随着孔隙度降低,温度阈值随冲击速度升高的速率有所加快.在不同材料中,在冲击强度一定的情况下,过程相似要求的温度阈值和孔隙度在一定范围内表现出幂律行为.其他类型的特征结构可以按同样方式进行研究分析.

The physical fields in porous materials under strong shock wave reaction are very complex. We simulate such systems using the grain contact material point method. The complex temperature fields in the material are treated with via the morphological characterization. To compare the structures and evolution of characteristic regimes under various temperature thresholds, we introduce two concepts, structure similarity and process similarity. It is found that, within the same material, the structure and evolution of high-temperature regimes may show high similarity if the shock strength and temperature threshold are chosen appropriately. For process similarity in materials with high porosity, the required temperature threshold increases parabolically with the impact velocity. When the porosity becomes lower, the increasing rate becomes higher. For process similarity in different materials, the required temperature threshold and the porosity show a power-law relationship in some range. Other kinds of characteristic regimes can be studied in the same way.