Evaluation of tubular materials by a hydraulic bulge test

This paper aims to evaluate the properties of tubular materials by hydraulic bulge tests combined with a newly proposed analytical model. Annealed AA6011 aluminum tubes and SUS409 stainless steel tubes are used for the bulge test. The tube thickness at the pole, bulge height and the internal forming pressure are measured simultaneously during the bulge test. From above experimental data, the effective stress–effective strain relations can be derived by this analytical model assuming the profile of the free bulge region as an elliptical surface. The flow stresses of the tubular materials by this approach are compared with those obtained by the tensile test and Fuchizawa's model. The finite element method is used to conduct the simulations of hydraulic bulge forming with the flow stresses obtained by the above-mentioned models. The analytical results of forming pressures versus bulge heights are compared with the experimental results to validate the approach proposed in this paper.