IMPACT SHOCK LOADING OF POROUS MATERIALS: ANALYSES, EXPERIMENTS AND SIMULATIONS

摘要

Effects related with shock loading of porous materials during ballistic impact are considered. The stress-density diagram of many porous materials such as metal and polymer foams are characterized by its critical stress and strain, and the elongated plateau region where the density of the foam material increases from the initial density to a value approaching the density of the constituent material. The density increase corresponds to the collapse of the porous microstructure at the critical stress level. This property of porous materials defines their singular behavior under ballistic impact and can result in the formation of a shock wave under impact loading. The densification at the shock front is responsible for the major part of the ballistic energy absorption. The theory and numerical modeling of the ballistic interaction of a porous layer with a massive plate and its deceleration is presented. This simple model provides the foundation for analyses of more complicated problems such as interaction of a plate wave or projectiles with conical ends. Four velocity regimes which define the physics of interaction of plates and projectiles with the foam layer are identified. The Taylor cylinder impact experiment is found useful in the study of shock behavior of porous materials. Cylinder impact of porous material, numerical analysis and analytical theory is discussed.