Abstract In the field of defense technology and public security, asymmetric casings filled with explosive, especially the D-shaped casing, has received considerable attention. However, the effect of eccentric ratio on the fragment velocity distribution of D-shaped casing and its mechanism remain unclear. To obtain the velocity distribution of the fragments in the bottom part of the D-shaped casing, a kind of D-shaped casing with large length-diameter ratio was tested based on the X-ray photography technique. The experimental results show that the fragment velocity distribution of the D-shaped casing is not consistent with the results in existing studies. Then, a series of numerical simulation models were established and validated according to the experimental results, and the acceleration process of the fragments in the bottom part of D-shaped casing was numerically studied. The results indicate that the fragments in the bottom part of D-shaped casing are accelerated not only by the initial detonation wave but the detonation wave reflected from the arc part shell, which causes the inconsistency mentioned above. In addition, an empirical calculation formula was proposed based on the acceleration process of D-shaped casing and it was in a good accordance with numerical results. The findings herein could serve as a foundation for further research on the D-shaped casings and other kinds of asymmetric casings. It can also be a solid reference for engineering design of innovative warheads.

中文翻译：

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偏心起爆D形套管底部破片速度分布

摘要 在国防科技和公共安全领域，非对称装炸药弹壳，尤其是D形弹壳受到了广泛关注。然而，偏心比对D形套管破片速度分布的影响及其机制尚不清楚。为了获得D形套管底部碎片的速度分布，基于X射线摄影技术对一种大长径比的D形套管进行了测试。实验结果表明，D形套管的破片速度分布与已有研究结果不一致。然后，根据实验结果建立并验证了一系列数值模拟模型，数值研究了D形套管底部碎屑的加速过程。结果表明，D形套管底部的破片不仅受到初始爆震波的加速，而且还受到弧形部分壳体反射的爆震波的加速，导致上述不一致。此外，基于D形套管的加速过程提出了经验计算公式，与数值结果吻合较好。本研究结果可为进一步研究D形套管和其他类型的非对称套管奠定基础。也可为创新弹头的工程设计提供可靠的参考。结果表明，D形套管底部的破片不仅受到初始爆震波的加速，而且还受到弧形部分壳体反射的爆震波的加速，导致上述不一致。此外，基于D形套管的加速过程提出了经验计算公式，与数值结果吻合较好。本研究结果可为进一步研究D形套管和其他类型的非对称套管奠定基础。也可为创新弹头的工程设计提供可靠的参考。结果表明，D形套管底部的破片不仅受到初始爆震波的加速，而且还受到弧形部分壳体反射的爆震波的加速，导致上述不一致。此外，基于D形套管的加速过程提出了经验计算公式，与数值结果吻合较好。本研究结果可为进一步研究D形套管和其他类型的非对称套管奠定基础。也可为创新弹头的工程设计提供可靠的参考。根据D形套管的加速过程提出了经验计算公式，与数值结果吻合较好。本研究结果可为进一步研究D形套管和其他类型的非对称套管奠定基础。也可为创新弹头的工程设计提供可靠的参考。根据D形套管的加速过程提出了经验计算公式，与数值结果吻合较好。本研究结果可为进一步研究D形套管和其他类型的非对称套管奠定基础。也可为创新弹头的工程设计提供可靠的参考。