Testing Extrusion Flow Stress and Friction Factor via Inverse Analysis

Abstract

Accurate determination of flow stress and friction factor is the guarantee of accuracy for finite element analysis of metal extrusion. Firstly, flow stress equation parameters for materials test were initially decided in order to perform finite element analogy. Then, the simulation values and experiment values were compared and the iterative optimization algorithm was used to amend the parameters. The objective was that value error of simulation and experiment values was controlled within tolerance. Finally, accurate flow stress and friction factor were determined. In rod-rod composite extrusion experiment of pure lead,it is determined by inverse analysis that the material strength coefficient is 11.9, strain hardening exponent is 0.127,and friction factor is 0.18. The comparison of the load-stroke curve between simulation and experiment and pure lead upsetting test contribute to confirm that the measured data is accurate. The results show that inverse analysis is a precise, simple and practical method for measuring flow stress and friction factor.