Research And Development Of Drawbead Optimization In Sheet Metal Forming Simulation Base On Inverse Approach Of FEM

Generally, sheet metal forming is a high nonlinear mechanical problem about geometry, material and status. When engineers constitute the forming process of complicated parts or design die, they mainly depend on the qualitative academic analysis, a lot of experiential data and engineers'skills .Especially, the parameters such as blank hold force, drawbead, and so on the radiuses of die and punch are very important to the parts forming.The research work of this paper is supported by NCF and named as:"The Independent Research of High-speed Simulation and Optimal Process Design Aiming At the Formability of Automobile Panel"(No. 50575080). This paper discusses the inverse method of FE theory and developed inverse approach of FE programs used the triangle membrane element. This paper also discusses the research work about optimized drawbead parameters in sheet metal forming .Inverse approach can be used to optimize the process parameters. The distribution of elements in the FLC and WLC is defined as object function. This object function takes account of the fracture and wrinkle factors. The optimization method is BFGS method which has high efficiency to optimize. BFGS method iterates to optimize the object function. The method bases on first order gradient information. While calculating emendation matrix, it needn't the second order differential information. The emendation matrix which needs second order differential information is substituted with the HESSE matrix. Gold partition method is used in linear searching. Sensitivity formula is deduced based on inverse approach FE. The drawbead in sheet metal forming are optimized. Some examples are used to validate the drawbead optimization based on inverse approach FE feasibility and validity. Finally,some suggestions are given and may be reference to the coming research.