On evaluating impact responses of polymethyl methacrylate by piezofilm stress gauges

Abstract

An steady-wave-sensing-system (UWSS) is developed for evaluating the wave propagation characteristics of polymethyl methacrylate (PMMA) for loading-reloading-unloading waves using plate-impact experiments and three PVDF gauges. By applying the UWSS, stress, particle-velocity, strain and two kinds of phase velocities at one location in the PMMA are determined as functions of time. The phase velocities Uσ associated with the stress profiles are generally different from the other phase velocities Uν associated with the particle-velocity profiles. From loading to reloading are transitions very near from the Hugoniot in the stress-strain plane, but from reloading to unloading are transitions upward off the Hugoniot. In the region of our experimental stress, PMMA does not behave as liquid and the Hugoniot of PMMA is not effective for the loading-history-characteristics.