DETERMINATION OF FLOW STRESS BY THE HYDRAULIC BULGE TEST

摘要

In sheet metal forming operations the mechanical properties of the sheet metal (stress-strain curve, flow stress) greatly influence metal flow and product quality. Accurate determination of the stress-strain relationship is important in process simulation by finite element method. In this paper the sheet thickness gradation in different points of the hemisphere formed in the bulge test is analysed, both theoretically and experimentally. A precise determination of sheet thickness at the pole is very important in the precise determination of stress-strain relationship. The use of the hydraulic bulge test for estimation of flow stress under biaxial stress-strain state is discussed.