Optimizing Design of Two-dimensional Forging Preform by Bi-directional Evolutionary Structural Optimization Method

Preform is a step between blanking and finish forming. Design and optimization of the preform for forging would affect the material flow, forming load, dimension accuracy and tool wear. In this study, analysis, simulation and optimization process are carried out by utilizing MATLAB codes as well as using finite element analysis software (DEFORM-2D package) and CAD software as auxiliary tools. The results of this study are as following: using “Curve Fitting” method and two times of reference length are the better options for the boundary fitting method. Besides, the differences between using mean stress and normal pressure as an addition criterion were considered. In terms of strain, the average of effective strain is 0.643 and the standard deviation is 0.298 when using normal pressure as an addition criterion. These values are smaller than those using mean stress as an addition criterion, in which the values are 0.674 and 0.308, respectively. In terms of forming load, the value of the former is 70.616 tons. It is greater than value of the other criterion that forming load is 70.207 tons. Finally, in terms of shape, the results from normal pressure are more complex than those from mean stress.