Finite element analysis for thermoforming process of continuous fiber reinforced thermoplastic composites

Abstract An implicit finite element method is presented to model thermoforming process of thermoplastic materials reinforced with unidirectional fibers or woven fabric. The composite materials are regarded as a homogenized anisotropic viscous fluid restricted by kinematical constrains of material incompressibility and fiber inextensibility at the forming temperature. Unlike previous numerical approaches considering quasi‐static assumptions during each increment, a high order polynomial expression is used to define continuous displacement and velocity fields. The material parameters are also updated during each increment to determine the displacement and velocity fields satisfying the equilibrium equations as well as the kinematical constrains both in the rate and total deformation forms. An iterative solution method is presented to solve the finite element formulation. The numerical results are compared with analytical solutions and the results of previous implicit finite element approaches to demonstrate the computational accuracy and efficiency of the present method. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers