Sheet Forming Limit Theory Prediction And Its Application

The characteristics of sheet metal part are light in weight and high in stiffness. The parts of required shape and size can be made from different metal sheet according to the needs and have a wide application. In the forming process of the parts, the breaking or wrinkling of sheet metal may take place, and leads to the failure of the forming process. In the product and process design of sheet metal parts, by implementing the formability evaluation the actual production formation failure can be avoided effectively. Thus the product development cycle can be shorten and the cost of product development can be reduced. The formability evaluation of sheet metal parts is mainly based on sheet metal forming limit diagram (FLD). So it is very important to get the forming limit diagram of sheet metal. At present, the forming limit diagram is mainly gotten through a lot of experiments. The cost is high, and the dependence on loading path of forming limit can not be reflected. It is very important to study the theoretical prediction of forming limit diagram. Based on the analysis of several classical unsteady theory of sheet metal deformation, the corresponding forming limit diagram is made in this paper. The formability of several typical sheet metal forming parts is evaluated and predicted. The main research work of this paper is as follows:(1)The domestic and foreign research on sheet metal forming limit are summarized and analyzed.(2)The plastic forming theory with the anisotropic and isotropic yield criterion is reviewed and analyzed. The Swift diffuse instability theory, Hill localized instability theory and M-K theory are analyzed. And the forming limit diagrams are drawn.(3)Tensile tests of the SUS430 stainless steel and 6022 Aluminum Alloy were performed. The mechanical properties of the two kinds of materials are obtained.(4)The formability of a typical sheet metal forming part is predicted respectively based on the simulation results of two kinds of finite element analysis software DYNAFORM and ABAQUS. The prediction results are compared and analyzed.(5)The deep drawing and boring, taper drawing of SUS430 sheet metal, axial compression and necking process of SUS430 pipe are simulated and analyzed. The forming limits are studied and their formability are predicted.