A viscoelastic approach for modeling bending behavior in finite element forming simulation of continuously fiber reinforced composites

An approach for modeling rate-dependent bending behavior in FE forming simulation for either a unidirectional or a woven/bidirectional reinforcement is presented. The applicability of the bending model to both fiber architectures is guaranteed by introducing either an orthogonal or a non-orthogonal fiber parallel material frame. The applied constitutive laws are based on a Voigt-Kelvin and a generalized Maxwell approach. The bending modeling approaches are parameterized according to the characterization of thermoplastic UD-Tape (PA6-CF), where only the generalized Maxwell approach is capable to describe the material characteristic for all of the considered bending rates. A numerical study using a hemisphere test reveals that the Voigt-Kelvin approach and the generalized Maxwell approach lead to similar results for the prediction of wrinkling behavior. Finally, the approaches for modeling bending behavior are applied to a more complex generic geometry as an application test with a good agreement between forming simulation and experimental tests.