A multi-layer triangular membrane finite element for the forming simulation of laminated composites

Continuous fibre reinforced thermoplastics offer a cost reduction compared to thermosets due to promising fast production methods like diaphragm forming and rubber pressing. Forming experiments of pre-consolidated four-layer 8H satin weave PPS laminates on a dome geometry demonstrated that inter-ply friction is a dominant parameter in forming doubly curved components. Therefore, simulations of this process as sequentially draping the individual layers are invalid. A multi-layer triangular membrane finite element has been developed for efficient simulation of laminated composite forming processes with only one element in the thickness direction. Contact logic between the individual plies is avoided. The simulations were validated by comparison to the experiments mentioned and agree well. The multi-layer membrane element has shown to be capable of predicting the material instabilities during forming. They appeared to be unsuited for realistic wrinkling simulations due to their lack of a bending stiffness.