Based upon the principle of minimal Strain energy and the general flow rules corresponding with the yield function, the criterion of the onset of instable deformation of an orthotropic sheet metal in the tensile defor...Based upon the principle of minimal Strain energy and the general flow rules corresponding with the yield function, the criterion of the onset of instable deformation of an orthotropic sheet metal in the tensile deformation process is analyzed in the present paper. In this analysis, all kinds of those existing postulations, such as the presence of an initial defect in the material and a branch of its yield surface, are abandoned. It is shown from the analysis that for an infinitely small element of the orthotropic sheet metal, generally, when its load-bearing ability in the direction of maximal principal strain increment reaches the limit, it begins to lose its deforming instability, in a few of strain fields, the instable deformation occurs rather later till the following condition arrives. The stated condition is that the instantaneous direction in which the element’s load-bearing ability just reaches the limit at that time is moving to the orientation just perpendicular to the direction of zero strain increment. These criteria are first revealed by this paper.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘Based upon the principle of minimal Strain energy and the general flow rules corresponding with the yield function, the criterion of the onset of instable deformation of an orthotropic sheet metal in the tensile deformation process is analyzed in the present paper. In this analysis, all kinds of those existing postulations, such as the presence of an initial defect in the material and a branch of its yield surface, are abandoned. It is shown from the analysis that for an infinitely small element of the orthotropic sheet metal, generally, when its load-bearing ability in the direction of maximal principal strain increment reaches the limit, it begins to lose its deforming instability, in a few of strain fields, the instable deformation occurs rather later till the following condition arrives. The stated condition is that the instantaneous direction in which the element’s load-bearing ability just reaches the limit at that time is moving to the orientation just perpendicular to the direction of zero strain increment. These criteria are first revealed by this paper.
