柱壳约束对散心冲击波空间分布的影响

结合实验和数值模拟，研究了散心冲击波在金属柱壳约束下沿有机玻璃内部的空间分布。进行了点起爆柱状炸药驱动飞片加载实验，采用Polyvinylidence Fluoride (PVDF)测试方法对有机玻璃内部的压力进行测试。实验结果显示:在冲击波传播过程中，在特定传播距离处，离中心轴越近，冲击波第一幅值压力越小，这是因为散心冲击驱动飞片成前凸形状，在飞片飞行过程中与有机玻璃碰撞面积越来越大，在远离对称轴部位冲击压力叠加累积效应更强引起的；但在随后的冲击波传播过程中，由于受到柱壳约束影响，离对称轴越近，冲击波幅值越小，这是由散心冲击波在约束柱壳边界反射与冲击波波阵面叠加的结果。通过对炸药网格大变形溢出柱壳翻转进行合理处理，对实验进行了数值模拟。数值模拟结果所得的冲击压力沿径向分布规律计算结果与实验结果定性相符。最后探讨了不同约束程度对这一规律的影响程度，结果表明，后续的冲击波幅值随着约束的增加而急剧增加。

Influence of cylindrical shell on spatial distribution of pressure during propagation of divergent shockwave

The propagation and spatial distribution of the divergent shock wave in PMMA under the restriction of a metal cylindrical shell were studied using experiment and numerical simulation.The flyer was driven by the cylinder high explosive initiated by a detonator at the center of the free surface and the inner pressure of PMMA was measured by PVDF.The experiment shows that the closer to the axis at a unique spot,the smaller the first pressure amplitude,which is the result of the increased impacted area of PMMA by the forward convex-shaped flyer due to the divergent shock wave and the increased integrative and accumulative effect of the pressure beyond the axis.But during the subsequent propagation of the shock wave,the closer to the axis,the smaller the pressure amplitude,which is the result of the interaction between the shock wave front and the reflection of the divergent shock wave from the cylindrical shell.The numerical simulation was performed well by adjusting the severe distortion of the mesh which may cause the termination of the calculation.The trend of the numerical result is in qualitative agreement with that of the experiment.Finally,we discussed the effect of different shell materials on the law of the distribution of the shock wave,and it is shown that the subsequent pressure increases as the heavy density of the cylindrical shell increases.