Sensitivity of material properties on wrinkling behavior and fiber reorientation of thermoplastic UD-Tape laminates during forming analyzed by Finite Element forming simulation

Thermoforming plays an increasingly important role in manufacturing of structural composite vehicle components. Nevertheless, a macroscopic buckling and a subsequent wrinkling of the blank is often observed during forming. Additionally, a fiber reorientation is inevitable. Both of these mechanisms emerge in dependence on material properties of the main deformation mechanisms, which namely are shearing and bending of the single ply, as well as friction between the single plies of the stacked laminate. To predict forming behavior by means of Finite Element forming simulation, these mechanisms are modeled via constitutive laws, which facilitates the prediction of the stress and strain distribution during forming, as well as the shape of the formed product. To investigate the influence of the material properties of the above mentioned deformation mechanisms on wrinkling behavior and fiber reorientation, a sensitivity study based on the Design of Experiments (DOE) methodology is conducted. The influence is examined quantitatively by means of Response Surface Methodology on basis of quantitative measures for the examined mechanisms. It could be shown, that for the examined biaxial layup shearing and bending properties have a significant influence and friction between the plies plays a minor role.