低气压条件下爆炸及其对薄壳结构作用的数值模拟

Numerical Investigation on Air Explosion and Its Effect on Thin Shell Structure Under Low-Pressure Condition

在低气压条件下爆炸实验存在尺寸受限、传感器难以布控等难题,需要评估不同环境压力下结构在爆炸载荷作用下的响应。针对低气压条件下爆轰产物与外界空气的压力比、密度比、压强比较大,在数值模拟中极易出现密度或压力为负的问题,利用自主研制的空中爆炸高精度大规模计算方法,二次开发ABAQUS压力加载接口程序,实现爆炸流场与壳体结构的显式流固双向耦合,对比了常压与低气压条件下爆炸载荷对Q235钢质薄壳结构的作用过程。研究发现:在低气压(80 Pa)条件下,炸药爆炸后难以形成冲击波,爆炸后的能量均以爆轰产物形式向外传播,正压作用时间及冲量与常压(101 kPa)条件基本一致;在两种环境压力条件下,爆炸载荷加载到Q235钢质薄壳后产生的壳体变形量、等效塑性应变、速度等物理量相似,壳体结构破坏模式基本相同。因此,常压下的壳体内爆炸实验可以在一定程度上代替低气压环境下的实验。

There exists difficulties such as the size is limited and the sensors are hard to control in the air explosion experiment under the low-pressure condition,so it is necessary to evaluate the response of the air explosion load on the structure under different environmental pressures.In order to solve the problem that in the numerical investigation,the pressure ratio,density ratio and pressure intensity ratio between the detonation products and the outside air are so large that the density or pressure easily become negative under the low-pressure condition,a self-developed high-precision large-scale calculation method of air explosion was used,the ABAQUS pressure loading interface program was secondarily developed,as to realize the explicit fluid-structure interacted coupling between the air explosion flow field and the shell structure,and further,the effect process of the air explosion load on the Q235 steel thin shell structure under the normal-pressure and low-pressure conditions were compared.Findings:Under the low-pressure condition(80 Pa),it is difficult to form shock wave after the air explosion of explosives.The energy generated by the air explosion spreads outward in the form of detonation products,and the time and impulse of positive pressure are basically the same as that under the normal-pressure condition(101 kPa).Under the condition of two environmental pressures,physical quantities such as the shell deformation,equivalent plastic strain and velocity generated by the air explosive load on the Q235 steel thin shell are similar,and the failure mode of the shell structure is basically the same.Therefore,the air explosion experiment in the shell under the normal-pressure condition can replace the experiment under low-pressure condition by some extent.