An Iterative Numerical Approach to Evaluate the Variable Friction Coefficient of Steel AMS5643 Using Ring Compression Tests

The coefficient of friction is an important variable that must be defined to allow the accurate prediction of the forming geometry and stresses involved in metal forming processes. Literature reports have shown that the coefficient of friction does not remain constant with respect to variables including but not limited to contact pressure, sliding speed, surface roughness, and surface morphology. Ring compression tests provide a simple and efficient process by which to measure the variable coefficient of friction present in the bulk-metal process; however, the conventional interpolating method can result in a poor evaluation of the evolution of friction, especially if the coefficient of friction changes significantly during a test. In this article, a novel approach to evaluate the relationship between the coefficient of friction and contact pressure is outlined using friction calibration charts generated via iterative computation models and ring compression tests. This relationship can be programmed into a computational model to allow for the coefficient of friction to behave as a dynamic variable. This approach improves on the prediction of the computational model when compared to conventional interpolation methods.