2017 Volume 35 Issue 2 Pages 80s-84s
This study investigated the influence of impact velocity for the V-notched Charpy specimen on the transition time, tT, which is defined as the time when the kinetic energy is equal to the deformation energy of the specimen. The tT indicates the point in the response after which inertial effects diminish rapidly. In this study, dynamic stress/strain fields in the V-notched Charpy specimen were numerically analyzed by means of three-dimensional dynamic explicit finite element (FE) analysis. This analysis considered the effect of high-speed strain rate on the flow stress and the increase in temperature during impact loading. The contact problem between the specimen and the striker of Charpy testing machine was solved using the Hertzian contact theory. This FE-analysis shows that the tT decreases slightly with increasing impact velocity over the range from 1 to 10 m/s. The deformation energy increases more rapidly than the kinetic energy with increasing impact velocity. The increase in the deformation energy leads to shorter tT. The tT depends on the strength class of steels. The tT decreased with decreasing in strength of steels, because of the reduction of kinetic energy.
