Lateral Release Waves in Shocked Solids

Many types of shock-wave experiments and applications are affected by lateral release waves, but the literature on how to calculate their leading characteristic release wave is inadequate. We present the basic equation involving sound speed, shock-wave velocity and particle velocity in shocked materials, how to evaluate sound speed, and tabulated data for several materials. The key point that enables these calculations to be done easily is recognition that the shock Hugoniot and isentrope for any material are tangent to one another at a point, such as the beginning of relaxation from a shock state down onto the isentrope. This is familiar in detonation theory, where the detonation product isentrope is tangent to the detonation-product Hugoniot at the Chapman-Jouguet point (as well as to the Rayleigh line). Lateral release waves are also the mechanism that controls initiation spot size in explosives. Results of such calculations can guide the design of gas-gun impact experiments in which one wants to complete measurements within the 1-D flow region. Similarly, systems for initiation of explosives may be evaluated and designed in a way that provides for detonation to be attained within the most strongly shocked region, by making use of 1-D Pop plot information. These calculations pertain also for laminates of different materials, for example the shock initiation of detonation through a metallic bulkhead.