纵向磁场对聚能射流极限拉伸系数的影响

Influence of longitudinal magnetic field on coefficient of ultimate elongation of shaped charge jet

在分析纵向磁场能够增强聚能射流稳定性的基础上,根据聚能射流的运动方程以及聚能射流的塑性失稳条件,推导得到了聚能射流在纵向磁场中的极限拉伸系数计算公式,并计算了有、无磁场情况下极限拉伸系数的比值。通过两种炸高下的实验研究对理论模型进行了验证。结果表明:由于磁场的存在而引起的电磁力抑制了聚能射流颈缩的发展,进而延长了射流成型的惯性拉伸阶段,最终使聚能射流在磁场中的极限拉伸系数在一定程度上得到了增加;理论和实验所得结果吻合较好。运用所建立模型可以较准确地反映磁场对聚能射流极限拉伸系数的影响。

The coefficient of the ultimate elongation is one of significant parameters related with theoretical calculations of a shaped charge jet（SCJ）.Based on the effect of a longitudinal magnetic field on the stress-strain of SCJ,and following the motion equation and the plastic instability condition,the formula of the coefficient of the ultimate elongation of a shaped charge inside the magnetic field was obtained and,using this formula,the ratio of the coefficient of the ultimate elongation was calculated respectively with and without the existence of a magnetic field.In addition,the theoretical model was verified through the experiments with two different standoffs.The results indicate that the electromagnetic force arising from the deformation of the SCJ due to the magnetic field that has penetrated into its material inhibits the development of the necking,and extends the stretching stage before the SCJ breaks up into particles,thus increasing the coefficient of the ultimate elongation.Predictions from the theoretical calculation are in good agreement with the data obtained from the experiments.