In the current work, a series of step-by-step research methods have been applied to address the damaging effects of near-field strong shock waves and high-speed fragments on covered charge. In the first step, the defects of covered plates due to high-speed fragments were simplified to penetrated notches, and then, these notches were used to evaluate the impact of shock wave loads on charges covered with metal plates. In the next step, we developed a theoretical model to take into account the shock initiation of charges covered with defected metal plates. Explosive initiation standards coupled with shock wave evolution characteristics were applied to specify the crucial conditions of explosive detonation. Finite element program, for instance, was applied for the simulation of shock initiation processes in pressed charges (when TNT was covered with a steel plate containing a penetrated notch), and then, numerical simulations were validated by experimental findings. Finally, the results obtained from the numerical simulations and theoretical model were applied to evaluate the impacts of shock wave intensity, the thickness of covered metal plate, and the geometrical features of penetrated notch on pressed charge shock initiation. The least squares method was applied to determine critical initiation criteria (n and K). Theoretical calculation results were found to be highly consistent with those obtained from numerical simulations, indicating that covered metal plates significantly contributed to charge protection. The results also revealed that notches could undermine the protective function of covered plates and the size and shape of notch significantly affected charge critical detonation distance. Critical detonation distances of noncontact explosions were found to be 25 and 81 mm for a 3 mm thick pressed TNT in the presence and absence of 45# steel-covered plate, respectively. According to the results, increase in the diameter of covered plates containing a cylindrical notch increased pressed TNT critical detonation distance. When dealing with a covered plate containing a normally reflected frustum notch, however, we figured out that any increase in normal reflection slope could decrease pressed TNT critical detonation distance.

中文翻译：

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冲击波和碎片冲击下覆盖装药的冲击起爆研究

在目前的工作中，已经应用了一系列循序渐进的研究方法来解决近场强冲击波和高速碎片对覆盖电荷的破坏作用。第一步，将高速碎片造成的覆盖板缺陷简化为穿透缺口，然后利用这些缺口评估冲击波载荷对金属板覆盖的装药的影响。在下一步中，我们开发了一个理论模型来考虑覆盖有缺陷金属板的电荷的冲击引发。爆炸物起爆标准与冲击波演化特性相结合，用于指定爆炸物爆炸的关键条件。以有限元程序为例，应用于模拟压制装药中的冲击引发过程（当 TNT 被包含穿透缺口的钢板覆盖时），然后通过实验结果验证数值模拟。最后，应用数值模拟和理论模型获得的结果来评估冲击波强度、覆盖金属板的厚度和穿透缺口的几何特征对加压装药冲击起爆的影响。应用最小二乘法来确定临界起始标准（被覆金属板的厚度，以及受压电荷冲击引发时穿透缺口的几何特征。应用最小二乘法来确定临界起始标准（被覆金属板的厚度，以及受压电荷冲击引发时穿透缺口的几何特征。应用最小二乘法来确定临界起始标准（n和 K）。发现理论计算结果与数值模拟结果高度一致，表明覆盖的金属板对电荷保护有显着贡献。结果还表明，缺口会破坏覆盖板的保护功能，缺口的大小和形状显着影响装药临界爆轰距离。发现在存在和​​不存在 45#钢包覆板的情况下，对于 3 毫米厚的压制 TNT，非接触爆炸的临界爆炸距离分别为 25 和 81 毫米。根据结果​​，包含圆柱形缺口的覆盖板直径的增加增加了受压 TNT 临界爆轰距离。但是，当处理包含正反射平截头体凹口的覆盖板时，