The reshock and release waves in PTFE

Polytetrafluoroethylene (PTFE) specimens were loaded by a single shock wave to 26 GPa followed by release as well as a complex structured wave consisting of the shock to 26 GPa followed by the smooth compressive wave to 33 GPa and subsequent release. The set of four stress histories recorded by the manganin gages was converted using the Lagrangian analysis into $(σ-ν)$—relations along the trajectory of the gages. The experiments revealed two types of steady wave-forms, which were treated within the context of the theory of wave propagation in nonlinear materials with fading memory. The $(σ-ν)$—unloading paths show the marked effect of hysteresis, which allows to estimate the shear stress of ≈0.4 GPa at the dynamic stress of ≈33 GPa.