Wave Propagation and Dynamic Load Transfer due to Explosive Loading in Heterogenous Granular Media with Microstructure

Abstract : An experimental and numerical investigation has been conducted to study wave propagation and load transfer due to dynamic loading in granular materials. Systematic as well as random aggregates of particles of different material properties as well as shapes were used to simulate the granular media. These assemblies were loaded either with explosives or projectiles driven by a gas gun to generate short duration pulses. The resulting dynamic phenomenon was experimentally studied by using the optical technique of photoelasticity and dynamic strain gage equipment. Of particular attention was the effect of local microstructure on the wave propagation process. The effect of the loading pulse wavelength as well as the material heterogeniety on the wave propagation phenomenon was evaluated. The effect of the particle shape and size on the load transfer process was also studied. Initial experiments were also conducted to investigate the effect of prestress as well as interstitial moisture on the wave propagation process. The experiment al results elucidated the basic mechanisms of load transfer, provided the duration and magnitude of the dynamic contact stresses, wave propagation velocities, envelope of load transfer and wave attenuation.