Comparison of Hydrostatic Extrusion between Pressure-Load and Displacement-Load Models

Two finite element analysis (FEA) models simulating hydrostatic extrusion (HE) are designed, one for the case under pressure load and another for the case under displacement load. Comparison is made of the equivalent stress distribution, stress state ratio distribution and extrusion pressure between the two models, which work at the same extrusion ratio (R) and the same die angle (2α). A uniform Von-Mises equivalent stress gradient distribution and stress state ratio gradient distribution are observed in the pressure-load model. A linear relationship is found between the extrusion pressure (P) and the logarithm of the extrusion ratio (lnR), and a parabolic relationship between P and 2α, in both models. The P-value under pressure load is smaller than that under displacement load, though at the same R and α, and the difference between the two pressures becomes larger as R and α grow