爆炸冲击下珊瑚砂动态本构模型

Dynamic constitutive model of coral sand under blast loading

以珊瑚砂为主要覆盖域的岛礁在面临动力灾变时,确定岛礁工程抵抗极端冲击荷载的阈值至关重要,珊瑚砂的动态本构关系是防护工程设计的关键要素。本文中,根据SHPB实验和静态压缩实验的结果,提出了一种基于应变率强化规律确定珊瑚砂物态方程的方法,并确定了珊瑚砂动态本构模型的参数。分别基于流体弹塑性模型和Perzyna黏塑性帽盖模型,结合LS-DYNA有限元程序,通过对侵彻和爆炸的数值计算,验证了模型的适用性。基于建立的模型,对不同相对密实度的珊瑚砂开展了侵彻和爆炸数值计算,结果表明,密实度对爆炸波的衰减影响较大、对侵彻深度的影响较小。

Coral sand is widely distributed in the large area of reefs and lagoons in the South China Sea.During the construction of various projects on islands and reefs,the coral sand is extensively used as a local material resource.It is very important to determine the threshold of the reef engineering to resist extreme impact loads when the islands and reefs covered with coral sand was suffered from dynamic disasters such as penetration and explosion.The coral sand dynamic constitutive model is a key component for protection engineering design when engineering calculations are required.Based on the results of SHPB experiment and static compression experiment of coral sand from the previous works,a method was proposed to determine the equation of state of coral sand based on the law of strain rate strengthening effect by comparing the static compression curves and the dynamic compression curves.It has been proved that the average pressure of the compression curve can reach more than 100 MPa by using this fitting method.The parameters of the dynamic constitutive model of coral sand were determined through the processing of a lot of experiment results.Based on the hydrodynamic elasto-plastic model and the Perzyna viscoplastic cap model,combined with the LS-DYNA finite element program,the applicability of the dynamic constitutive models was verified by contrasting the numerical calculations and experimental results of the coral sand suffered from the projectile penetration and the blasting of explosive.According to the established model,numerical calculations of penetration and explosion in coral sand with different compactness levels were carried out using the hydrodynamic elastoplastic model.The results show that the compactness levels of coral sand have a greater influence on the attenuation of the blasting wave and less on the penetration depth.This is because the poorly graded original coral sand has a smaller measurement difference between the maximum and minimum dry densities.