An effective semi-implicit integration scheme for rate dependent crystal plasticity using explicit finite element codes

A semi-implicit integration scheme for rate dependent crystal plasticity is developed in this work; the algorithm is similar as the classical tangent modulus method. A modified hyperelastic frame is adopted to circumvent the troublesome incremental objectivity encountered by the hypoelastic crystal plasticity models, especially when Green-Naghdi material co-rotational coordinate system (MCCS) is introduced. The algorithm combines the advantages of the tangent modulus method and the hyperelastic frame. It provides a straightforward and efficient way to treat the grain rotation under the MCCS, and the reliability is tested by the ODF simulation compared with orientations obtained by electron backscatter diffraction (EBSD). Numerical tests show that the cost and accuracy are close to the forward Euler and implicit algorithm under large time step, its cost is also less than tangent modulus method. This algorithm is implemented into ABAQUS/Explicit to simulate deep drawing of aluminum alloy sheets with two kinds of different initial textures. The predication of the earing profiles shows good agreement with the experimental results, and it is also found that the current model is considerable fast. The current algorithm shows good performance in the simulation of complex sheet metal forming under explicit FEM codes. (C) 2011 Elsevier B.V. All rights reserved.