Molecular Dynamics Simulation of Residual Stress Generated in EDM

Residual stress is one of the main characteristics of the surface machined by electrical discharge machining (EDM). In this paper, the formation mechanism of the surface residual stress, and its distribution were simulated using molecular dynamics methods. It was found that a larger pressure gradient was formed in the melting area during discharge. It was also found that there existed larger stress gradient in the melting region and in the solid region in contact with the melting area. The pressure gradient and the shear stress field is the important reason for the formation of the bulge of the discharge crater. From the distribution of the residual stress, it was found that the residual stress on the electrode surface is tensile while it is compressive inside the electrode, indicating that cracks are easy to be generated in the re-solidified layer.