A Novel Principle Stress Model to Predict the Stress and Load in Sheet Drawing

The solution of stress and load of metal sheet deep drawing serves as a primary basis for guiding production, verifying strength of dies, and optimizing technology parameters. Based on the differential equations, boundary conditions, theory simplification and solution equations, an principle stress model (PSM) to predict the stress distribution and deformation load in drawing processes with a blank holder were proposed, and then the results were compared with the predicted value by finite element method (FEM) under the same conditions. Due to the thickness of the flange in deformation zone remains basically unchanged under the action of blank holder, it is reasonable to simplify the solution of deformation to plane strain problem. The PSM and FEM predict that the radial tensile stress and circumferential compressive stress in the flange zones remain basically consistent trends, and the relative error of most of predicted results is less than 5%. The influence of the die fillet bending on the stress state of inner and outer sides is not consider, leads to the calculated stress and load by PSM slightly higher than those of FEM. The solution of stress and load solution by PSM is reliable and convenient, and the FEM predicts more detailed and accurate results but need consume much larger calculating time. This research is of great significance for improving the solution efficient and engineering applications of plastic mechanics in sheet deep drawing deformation.