Abstract
The relationship between the stress o and time t of an SUS303 round bar was measured using an intelligent universal test machine. The elasticity plasticity transition point o ・ which was a stress of the boundary of plasticity and elasticity, was obtained by the analysis of the measurement result. As the coordinates of the complementary energy Ec , the horizontal axis shows the load P and the vertical axis shows the deformation 8. Moreover, the analysis of the complementary energy Ec was carried out. The difference in the complementary energy Ec of each stress as a step stress a St was calculated twice. The elasticity plasticity transition point a ep was obtained by this method. A static torsion test on an FCD370 round bar was also carried out. The difference in the complementary energy Ec of the FCD370 round bar was calculated twice similarly to that of the SUS303 round bar. The elasticity plasticity transition point r ep of the FCD370 round bar was obtained.
