自然歪を用いた有限変形の弾塑性解析に関する研究

（引張後に剪断の予変形を与えた後の繰り返し荷重下の降伏応力について）

抄録

The purpose of this study is to elucidate the yield phenomena under cyclic loads obtained after applying large pre-deformations on basece of the Natural Strain theory which is a reasonable strain representation under finite deformation. As for the method for determining yield stresses during cyclic loads, the slope of tangent in the principal deviatoric stress- principal deviatoric strain curve is used instead of conventional method by proof stress. In the early stages of this study, the yield stresses during cyclic loads such as uniaxal tension or compression and simple shear have been investigated focusing on the most fundamental deformations that the type of pre-deformation is the same as the type in cyclic load. As the next stage, yield phenomena have been examined under condition that the type of pre-deformation is different from the type in cyclic loads. Moreover, in the present study, the combined deformations of tension and shear are selected as the pre-deformation. Especially, yield stresses during cyclic loads obtained under pre-deformation of shear after uniaxial tension are examined in this paper. Then, changes of yield stresses with an increase of number of cycle are investigated to the cyclic loads concerning the tension and compression or forward and reverse shear.