Stress Wave Propagation Through Heterogeneous Media
Final progress rept. 15 Apr 1998-30 Sep 2001
CALIFORNIA INST OF TECH PASADENA GRADUATE AERONAUTICAL LABS
Pagination or Media Count:
In heterogeneous media, scattering due to interfacesmicrostructure between dissimilar materials could play an important role in shock wave dissipation and dispersion. In this work the influence of interface scattering on finite-amplitude shock waves was experimentally investigated by impacting flyer plates onto periodically layered polycarbonate6061 aluminum, polycarbonate304 stainless steel and polycarbonateglass composites. Experimental results obtained using velocity interferometer and stress gage show that periodically layered composites investigated can support steady structured shock waves. Due to interface scattering, the effective shock viscosity increases with the increase of interface impedance mismatch, and decreases with the increase of interface density interface area per unit volume and loading amplitude. The strain rate within the shock front for the composites studied increasing by about the square of the shock stress, comparing with the increasing by the fourth power of the shock stress for homogeneous metals, indicates that layered composites have much larger shock viscosity due to the interfacemicrostructure scattering. Experimental results also show that due to the scattering effects, shock propagation in the layered composites is dramatically slowing down and the shock speed in composites can be lower than that of either its components.