自然歪理論に基づく大きな単純剪断変形下の降伏曲面

（大きな剪断変形後に逆方向の剪断変形を与える際の降伏応力と逆方向の剪断の予変形量の関係）

抄録

This paper describes the progression of anisotropy in the yield surface formed during the process of applying a large simple shear. In our previous studies, the yield phenomenon has been investigated by using the test pieces, which are applied the simple shear in the reverse direction after large simple shear in the forward direction. Then, the shape of yield surfaces has been estimated on the basis of the slope of tangent in the deviatoric stress and deviatoric strain curve, which is represented by using the Natural Strain. Consequentially, since the anisotropy appears on the reverse shear side, it is revealed that the anisotropy is newly formed during the process of applying a reverse shear. In the present study, in order to examine the developing process of anisotropy more in detail, the transitions of yield stress on the forward shear side and the reverse shear side are investigated by changing the size of pre-deformation in the reverse shear side variously.