爆轰波对碰驱动平面锡飞层的动力学及动载行为特征研究

强冲击下的物质变形、破坏及诱发的轻重介质混合问题,是内爆压缩科学和工程应用领域的研究重点.本文针对爆轰波对碰条件下的复杂加载动力学过程及其动载破坏形态特征,开展数值模拟研究与极曲线理论分析.设计了爆轰波对碰驱动平面锡飞层的计算模型,获得了爆轰加载动力学过程及波系相互作用物理图像,分析了锡飞层对碰区自由表面速度历史的典型特征.给出了锡飞层中折射激波对碰发生马赫反射的临界条件,解读了三波结构的传播行为,阐明了对碰区内存在"一维正冲击"区域,一维区外存在单次斜冲击向两次斜冲击过渡的复杂加载动力学过程,提出了对碰区冲击动力学模型,揭示了影响对碰区动载行为特征的机理.数值模拟结果与极曲线理论分析结果相互印证,符合较好.本文的研究成果,将为深入理解和解读对碰区特殊的物质破坏及混合现象提供重要的理论支撑.

Loading characteristics and dynamic behaviors of the plane tin flying layer driven by detonation collision

Under strong impact loading, metal materials will produce deformation and show ejecta behaviors. The mixing phenomenon, due to the detached matters entering into the background fluid, has a direct influence on the compression properties. According to the researches of ejecta, the damage and mixing are closely related with the loading state and the dynamic process. Up to now, many results have already been obtained under the condition of the directive impact of detonation. Further study on the metal materials response driven by detonation collision is needed. Previous studies have focused on the macro characteristics, such as the collision uplift and destruction. In this paper, we aim at the wave system's interaction process, in order to obtain the physical detail and to reveal the mechanisms of dynamic behaviors in the collision region. Investigations are carried out by means of both the numerical simulation and the shock polar theory analysis. Planer tin flying layer calculation model is designed for numerical simulation, so the sliding wave systems and shock conditions are obtained effectively. Based on the numerical results in the plane tin flying layer, the shock polar theory forecasts that the Mach reflection will occur, and the images of wave interactions given by numerical simulation also display the three-wave structure, which is the typical structure of the Mach reflection. Quantitative comparisons between the numerical results and theoretical analysis of the shock polar are in good agreement with each other. Furthermore, the critical conditions of Mach reflection in the cases of different shock conditions are given. Meanwhile typical characteristics of the histories of free surface velocity in the collision zone are analyzed. From the numerical and theoretical analyses, the shock dynamical model in the collision zone is proposed to reveal the mechanisms, and the model is very important for investigating the collision zone problem deeply in decomposition way. The results illustrate that in the collision zone there exist multiple kinds of shock loading ways, including one-dimensional once plane impact region, two-dimensional once oblique impact region, and two-dimensional twice oblique impacts region. The complex loading dynamic processes coupling with the unsteady flow field lead to the distributions of the peak pressure at different positions in the collision zone. The corresponding destroyed behaviors are shown, and thus we can establish the relationship between the reflection wave structure and the fracture morphology of the collision zone. This research results will provide an important theoretical support for the understanding and interpretation of the physical phenomena of material deformation, damage and mixing in the collision zone.