In order to determine constitutive relationship of tubular materials accurately, a novel approach was proposed by means of the incremental theory based on the data of tube hydraulic bulge test. The three-dimensional displacement field of the bulging zone was measured on-line and real-time via three-dimensional strain measurement system in the test, and then the strain field and wall thickness thinning were obtained through the calculation. Thus, the pre-assumption of bulged profiles was avoided. Finite element simulations of tube hydraulic bulge with the material parameters which were determined by increment theory, total strain theory and uniaxial tensile test respectively, were performed to obtain the maximum bulge height and bulge profiles, and they were compared with those obtained by the test to verify the reliability of the proposed approach. The results show that the deviations of those results obtained by means of incremental theory are the smallest, which are in a range of less than 6.7%. That is to say, the approach by means of the incremental theory can predict the constitutive relationship of tubular material more precisely.
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