平面激波加载下砂墙结构的冲击响应特性

砂墙结构在爆炸安全防护领域具有广泛应用,为了研究激波加载下砂墙结构的冲击响应特性,基于水平激波管实验装置,开展平面激波冲击砂墙结构系列实验,采用高速纹影摄像系统捕捉流场中激波波系的演化过程和砂墙结构的运动过程。入射激波马赫数为1.827~2.413,相应入射激波载荷强度为0.378~0.724 MPa。砂墙结构利用铁砂、矾土、石英砂3种实验用砂制备,所制备砂墙结构孔隙度分别为56.6%、69.3%、56.6%。高速纹影照片显示:平面激波冲击砂墙结构发生反射和透射,伴随入射激波和透射激波的传播,在百微秒内,砂墙未产生显著运动,表现出显著的类固体动力学响应特性。基于冲击理论,确定了铁砂墙、矾土砂墙、石英砂墙的线性冲击关系,冲击关系中线性常数λ值量级为100,根据凝聚介质实用状态方程推断:较低强度载荷冲击作用下,砂墙主要产生体积变形,而由冲击引起的热能效应则可以忽略。

Dynamic responses of sand wall under planar shock loading

In order to study the dynamic response behavior of a sand wall in the process of the shock-sand wall interaction, experiments are carried out in a horizontal shock tube. A high-speed schlieren imaging system is used to capture the instantaneous structures of shock wave and moving process of the sand wall in the flow field. The incident shock Mach number ranges from 1.827 to 2.413, and the incident shock strength ranges from 0.378 MPa to 0.724 MPa. Three different kinds of sand walls are constructed using well-size-distributed iron sand, bauxite sand and quartz sand, the corresponding porosities of these sand walls are 56.6%, 69.3% and 56.6%, respectively. High-speed schlieren photographs show that regular reflection occurs when the incident shock wave impacts the sand wall. Moreover, the sand wall does not move significantly until the hundreds of microseconds after the onset of the interaction, indicating that the dynamic response behavior of the sand wall is similar to that of a rigid body. Basing on the shock wave theory, the Hugoniot relations for sand walls made from three different materials are established. The bulk elastic moduli of iron-, bauxite- and quartz-sand walls are 0.913, 0.478, and 0.225 GPa, respectively. The constant λ in the Hugoniot relations is on the order of 100. It is concluded that the relatively low shock impacting majorly leads to the volume deformation of the sand wall, and the heat effect of the sand wall caused by shock loading may be unimportant.