Mechanical theory of strain rate sensitivity index m and new method of measurement using constant load

Abstract

In this paper, a set of formulae to determine the value of m (strain rate sensitivity index) using the experimental parameters gauge length l, crosshead velocity V, and load P has been derived from the fundamental definition of m so that a reasonable basis for classification of various methods of measuring m is obtained. A new formula for determining the value of m under constant load has been put forward and based on this new formula a method of measuring and testing equipment for the determination of the value of m under constant load has been studied. Furthermore, the functional relationships between m_l, m_v, and m_p have been determined through mathematical analysis. Finally, a unified method of measuring m_l, m_v, and m_p from one group of tensile testing curves under constant load has been obtained. The experiments have shown the theory and the experimental results to be in such good agreement that the unified theory of phenomenological mechanics and the unified methods of experimental measurement of values of m have thus been reasonably established.

MST/823