Effect of distortional hardening behaviour on material responses of pure titanium sheets during hydraulic bulge test

Abstract

Plastic deformation characteristics of pure titanium sheets are identified by conducting tensile tests and hydraulic bulge test. Distortional hardening behaviour of the tested material is examined experimentally by comparing the uniaxial tensile results of three specimens taken from different orientations. This study verifies the effect of the distortional hardening behaviour on the material responses for pure titanium sheet by conducting a finite element analysis for the bulge test. For this purpose, a material model is calibrated based on the experimentally measured data. In this model, both yield surface and potential surface were well described by the Yld2000-2d function under the theory of associated flow rule. To match with experimental observation, all parameters of the yield function are implied as functions of the equivalent plastic work during plastic deformation. Additionally, a modified Voce hardening function was applied to reproduce the hardening behaviour for the examined material over large strains. Based on simulation results, it is concluded that the distortional hardening behaviour strongly affects the evaluation of the apex height during the bugle test.