Model Element Method And Fundamental Research Of Finish Forging Model Element

Metal plastic deforming process is a kind of quite complex and large elastic-plastic deformation process. The complexity of deformation mechanism contributed by the material and geometric nonlinearity, the nonlinearity of the complex boundary contact condition make the exact mathematic description of plastic deformation impossible. With the lasting development of metal plastic deforming technology the deformation mechanism and mechanical analysis of deformation process begin to attract more and more attention. As an effective method of numerical computation, FEM is widely applied in numerical simulation of metal deformation process. However FE softwares still cannot solve some problems such as accuracy of numerical simulation and optimum design. In this paper MEM (model element method) and its application are presented and fundamentals architecture is created for quantitative describing the deformation process of open die forging. This paper is part of a project sponsored by NSFC, which opens a new path or method for describing metal plastic deformation process and has its significance in theory and practice.This paper stated the fundamentals, features and solving process of MEM which includes the division of model elements and time domain, the creation of strain force distribution curve and the optimum design of deformation process parameters. In model element method to obtain model elements of a deforming body is to determine the feature stages in time domain of a deforming process and then divide the deforming body in different feature stages into several model elements in spatial domain along with some special physical surfaces such as die parting face, flow diversion face, interface of plastic and nonplastic zone, die cavity working face. The quantitative description of a model element includes: 1. the instant deforming force and its distribution function in deforming process; 2. the instant shape and dimension of model element in deforming process; 3. the deformation field of the instant model element; 4. the stress field of the instant model element; 5. the correspondent relationship of instant deforming force distribution and the geometry of subject.By using MEM slip line fields of model element of finish forging phase are studied in four cases: 1. b=0 and h0 2hc+hf, 2. b=0 and h0>2hc + hf, 3. b 0 and h0 2hc + hf, 4. b 0 and h0>2hc + hf. According to slip line fields the quantitative descriptions of them are obtained by curve fitting in numerical analysis software Origin 5.0 and Matlab 6.1. The results include geometry, strain force field expression and deformation force of model elements. In addition, an example is given to compare the results of theory and experience which are in good accordance with each other. It is shown that MEM is a good way to describe the metal plastic deformation.