FINITE ELEMENT ANALYSIS OF ENDLESS FIBER REINFORCED THERMOPLASTICS

摘要

The increasing economical importance of endless fiber reinforced thermoplastics demands for accurate but simple calculation methods to consider their nonlinear material behavior. Since the classical laminate theory (CLT) is difficult to apply to nonlinear materials, other approaches have to be used for thermoplastic composites. It is physically reasonable to model fiber and matrix separately because thereby different material models are applicable to the linear-elastic fiber and the viscoelastic matrix. A smart way to achieve this is offered by so called rebar (reinforcement bar) elements implemented in some modern FEA programs. These element types allow the simulation of the nonlinear material behavior of thermoplastic composites but face problems in some cases. This paper describes investigations on the accuracy, possibilities and limitations of modeling thermoplastic composites using rebar elements. A comparison between short-term and long-term tensile tests and simulations is given. To understand and to estimate the inaccuracy introduced by the simplified way of modeling using rebar elements, some additional microme-chanical simulations are carried out on a representative unit cell. The rebar element approach is applied to an exemplary structural component and the short-term and long-term simulations emphasize the advantages of considering nonlinear material effects in the component design.