二種の高分子内衝撃波面における応力・ひずみ特性のひずみ速度効果

Abstract

For numerical design of safety compartments in a cabin of aircraft to maintain a survivable environment for passengers in a crash, very-high-strain-rate mechanical-properties of many kinds of aerospace materials are indispensable. On the basis of the Unsteady Wave Sensing System (UWSS), which is composed of a plate impact experiment using three in-material gauges and nanosecond Lagrangian analyses, various variables are determined at the sensing part of the central gauge. Three stress-time histories are measured by three PVDFgauges, respectively, and the time histories of the phase velocity associated with the stress : Uσ, particle velocity : v, the phase velocity associated with the particle velocity : Uv, and strain : e induced by impact at velocities ca. 600m/s are calculated by using those three stress-time curves and the conservation relations of mass and momentum. Then, the stress-strain curves at very high strain-rate of the order 106 to 107s−1 are derived under conditions of uniaxial strain. On the other hand, stress-stain curves at medium strain rate (ca. 102s−1) and at low strain rate (ca. 10−4s−1) under conditions of uniaxial stress were already determined by a drop-weight testing system and Instron testing machine, respectively. It is clearly shown that the stress-strain curves for PMMA and polycarbonate (PC) are both very sensitive to strain rate in the very wide range of strain-rate of 10−4s−1 to 107s−1 under conditions of uniaxial strain. As a result, power law relations between stress and strain-rate were observed with these glassy polymers under uniaxial strain conditions in the very wide strain-rate range.