爆炸加载下变壁厚金属壳体纵向裂纹传播与碎裂机理研究

With the increasing damage power of weapons, the protective capability of important military targets is more and more strong. In order to improve the penetration warheads' bending strength and buckling resistance, variable wall thickness conical structure was often used, but the fragmentation mechanism especially the longitudinal crack propagation and interaction mechanism of variable wall thickness shell were still unclear. For the urgent need of research on variable wall thickness shell's fragmentation mechanism and fragments' statistical characteristics, the longitudinal fracture propagation and the fragmentation mechanism of variable wall thickness metal shells under explosive loading are researched by combining the experimental, theoretical and numerical simulation. Study on explosion experiment of various materials and structures shells, and fragments' fracture surface metallographic observation and statistical analysis will be carried out; the generation, propagation and interaction mechanism of longitudinal crack will be analyzed by using the high-speed photography technology; the fragmentation mechanism of metal shell with variable wall thickness was analyzed from multiple perspectives. It is expected to reveal the interaction mechanism of longitudinal fracture of metal shell with variable wall thickness and its influence on the fragmentation process under internal explosive loading, and the relationship between the statistical laws and the physical mechanism of shell dynamic fragmentation. This project not only has an important background of military application, but also analysis the longitudinal fracture propagation and fragmentation mechanism of the metal shell from a special new perspective, so it has high scientific value.

随着武器装备毁伤威力不断提高，重要目标的防护能力越来越强，为改善侵彻战斗部抗弯强度和抗失稳性能，常采用变壁厚锥形结构，但其碎裂机理尤其是纵向裂纹的传播与相互作用机理尚不清楚。针对变壁厚壳体的碎裂机理和破片统计特征相关研究的迫切需要，拟通过数值模拟、试验和理论相结合的方法，开展爆炸加载下变壁厚金属壳体纵向裂纹传播与碎裂机理研究。实施多种材料与结构壳体的静爆试验研究，进行破片的断裂面金相观察与统计分析；利用高速摄影技术分析壳体在内部爆炸加载下纵向裂纹的产生、传播和相互作用规律；进而从多角度分析总结变壁厚金属壳体碎裂机理。以期揭示在内部爆炸加载下变壁厚金属壳体纵向裂纹的相互作用机理及其对碎裂过程的影响，以及壳体动态碎裂的统计现象与物理机理的关系。本项目不仅具有重要的军事应用背景，还从新的视角研究金属壳体的纵向裂纹传播与碎裂机理，因而具有较高的科学价值。

本项目以深侵彻战斗部为背景，针对变壁厚壳体结构在内部爆炸加载下的碎裂机理开展研究。首次系统地给出了变壁厚壳体破片的形貌、断裂模式和质量分布，发现从大端起爆时，壳体外表面的裂纹扩展速度明显高于小端起爆时的裂纹扩展速度。根据Grady的能量平衡理论和Mott分布，建立了破片质量统计特征值与物理参数之间的半经验尺度关系。实验结果、理论分析和数值模拟结果基本一致。分析了壳体破片的微观特征，大锥角壳体从小端起爆时典型破片靠近壳体端面部分的厚度方向中部存在微裂纹和孔洞，剪切断裂模式与拉伸断裂模式的竞争导致了破片在该部位的断裂面非常不规则。开展了高强钢变壁厚壳体的静爆试验，分别从两端起爆，同时采用高速摄影技术和激光干涉测速技术联合观测变壁厚壳体的碎裂过程。首次获得了两种起爆模式下变壁厚壳体表面膨胀断裂过程图像和径向速度历程曲线。试验结果表明：从大端起爆时壳体表面裂纹传播速度远大于从小端起爆的情况，验证了之前的研究结果。本项目成果可指导战斗部中类似结构的威力或安全性优化设计，同时也将目前壳体的一维或二维动态破碎机理研究拓展到三维问题，因此具有较大的科学价值。