Abstract:
The majority of fiber reinforced plastic manufacturing processes involve compressive deformation of the reinforcing material to be included in the product. The development of accurate process simulations will in many cases be dependent on our ability to provide good models for the deformation of these reinforcing structures. The viscoelastic behavior of preform materials in the absence of any matrix has been investigated, and the implications for Liquid Composite Molding (LCM) processes considered. Extending existing Resin Transfer Molding simulations to predict local and total tooling forces will require the development of viscoelastic preform deformation models. For other LCM processes that involve cavity thickness changes during mould filling, an accurate preform deformation model is essential in order to simulate mould filling. An experimental study is presented demonstrating the strong time dependent viscoelastic compression behavior of common LCM preform materials. A nonlinear viscoelastic model has been developed for constant speed preform compaction. The required empirical parameters have been derived from a series of characterization experiments performed on the preform materials studied.