Deformation Prediction of Titanium Alloy in Incremental Sheet Forming with Anisotropic and Asymmetric Yield Function

The present study is concerned with the prediction of deformation in incremental sheet forming (ISF) for a Ti6Al4V sheet. To investigate anisotropic and asymmetric behaviors, uniaxial tension and compression tests were conducted along the rolling direction (RD), diagonal direction (DD), and transverse direction (TD). A representative yield function for a HCP material, the Cazacu-Plunkett-Barlat (CPB06) yield criterion, was selected for constitutive modeling to take into account anisotropy/asymmetry-induced distortional yielding of the titanium alloy. The chord modulus degradation was confirmed through uniaxial loading-unloading tests. The ISF tests were carried out using a single contact-point tool following a truncated pyramid tool path. To predict the deformation during the ISF, finite element analyses were conducted with the ABAQUS explicit and the vectorized user-subroutine (VUMAT). The performance of various constitutive models was evaluated based on the comparison of deformed shapes and distribution of thickness from the experiment and the FEA.