Preforming Analysis of Thermoformable Fiber Mats — Preforming Effects on Mold Filling

Abstract

A preforming and molding operation for producing an automotive hood was conducted. Irregular flow front profiles were observed because the preforming- induced deformation altered the flow characteristics of the fiber reinforcements. A fiber network model was established to estimate the stretching effect on permeability change. The permeability derived from this model was a function of two factors: porosity and ori entation. The predicted permeabilities compared well with experimental data. Bending- induced channeling was found to be the major cause for the observed irregular flow pat terns. When this effect was accounted for in the flow modeling, the profile of flow front progression could be simulated reasonably well.