Numerical simulation of EDM machining process and optimization for reduction of residual stresses
Abstract:
The high temperature gradient generated inside the workpiece through the process of electric discharge machining (EDM) causes high thermal stresses in a small area of the surface. These stresses remain to the ambient temperature and lead to the formation of residual stresses inside the workpiece. These stresses can lead to tiny cracks in the surface, reduction in resistance and fatigue life, and ultimately fracture. In this study, a finite element model (FEM) is developed to estimate the temperature distribution and distribution of thermal residual stresses resulting from electric discharge machining process on the workpiece. To predict thermal and residual stresses, this model first calculates the thermal distribution generated by electric discharge machining process inside the workpiece using thermal analysis. Then, with a mechanical analysis, the thermal stresses created due to the non-uniform thermal distribution are calculated and the residual stresses in the workpiece are calculated. Finally, the simulation results are compared with the existing experimental results and will be optimized by validating the results to minimize residual stresses in the workpiece. In the optimization method, an algorithm will be introduced that creates a polynomial mathematical model of residual stresses with different sections. This mathematical model is used to optimize the dimensions to reduce the amount of residual stresses and the resulting rise in the beams. The output of this research will provide useful information related to the optimal geometry of the workpiece used in electric discharge machining process.