Theoretical model of displacement response of circular plate under multiple explosive loads
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摘要: 圆板结构在多次爆炸载荷下的响应问题具有重要的工程意义,目前对此问题有较多试验与仿真研究,但从理论模型出发的研究尚缺少。本文针对圆板在多次爆炸载荷下位移响应的理论解开展研究,从基于膜理论的能量方程出发,将多次爆炸载荷简化为多次线性衰减脉冲,对第一次加载引起的位移场采用线性近似,对第二次加载后的位移场采用二次函数近似,同时考虑了应变率强化效应与多次加载硬化效应对材料流动应力的影响,给出了多次爆炸载荷下圆板位移响应的理论解。开展圆板二次、三次爆炸仿真,发现理论解对于二次爆炸中点位移预测值与仿真值误差主要在20%-30%范围,对于三次爆炸中点位移预测值与仿真值误差基本在20%之下。理论公式表明,圆板多次爆炸的中点位移可以表示为最后一次加载单独引起的位移与之前加载的累积位移的函数。后一次加载引起的位移增量小于其单独引起的位移,且这一增量大小与之前加载的累积位移有关,之前加载的累积位移越大,则后一次加载引起的位移增量越小。
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Abstract: The response of plate structures under multiple explosive loads has important engineering significance. Currently, there are many experimental and numerical studies on this issue, but research based on theoretical methods is still lacking. This article focuses on the theoretical model of displacement response of a circular plate under multiple explosive loads. The energy equation based on membrane theory is used to describe the motion of the circular plate. Multiple explosive loads are simplified into multiple linear decay pulses. The displacement field caused by the first loading is approximated by a linear function, and the displacement field after the second loading is approximated by a quadratic function. The effects of strain rate strengthening and multiple loading hardening on material flow stress are considered, and the theoretical solution of displacement response of the circular plate under multiple explosive loads is given. Simulations of dynamic response of the circular plate under two and three explosive loads are conducted by LS-Dyna. It is found that the error between the theoretical and numerical values of the midpoint displacement of the circular plate is mainly of the rage 20% -30% for the two explosive load conditions, and below 20% for the three explosive load conditions. Theoretical formulas indicate that the midpoint displacement of a circular plate under multiple explosive loads can be expressed as a function of the displacement caused solely by the last loading and the cumulative displacement of previous loads, which is the square root of the weighted sum of squares of the two, and the weighting coefficient depends on the form of the assumed displacement field. The displacement increment caused by the subsequent loading is smaller than the displacement caused by it alone, and the magnitude of this increment is related to the cumulative displacement of the previous loadings. The larger the cumulative displacement of the previous loadings, the smaller the displacement increment caused by the subsequent loading. -
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