Finite element simulation of SMC compression molding based on thermo-viscoplastic approach with fiber volume fraction prediction

SMC (Sheet Molding Compounds) is a thermosetting material which consists of unsaturated polyester resin and other additives reinforced with randomly distributed chopped fiberglass strands. During the compression molding cycle, it is very difficult to understand the overall effects of SMC resin components on flow characteristics and mechanical performance of the molded parts, since mold geometries and processing variables are complex. Thus, a three dimensional rigid thermo viscoplastic finite element program including chemical reaction and fiber volume fraction prediction was developed in the present study and applied to the analysis of compression molding of a SMC charge. To verify the validity of this approach, numerical fiber volume fraction predictions were compared to fiber volume fraction data measured by image processing. Three dimensional simulations under various molding conditions were carried out to obtain more thorough knowledge of the SMC compression molding process. Based on this study, it was found that the currently developed three dimensional finite element program coupled with heat transfer and chemical reaction can provide valuable information in understanding flow characteristics, fiber volume fraction distribution, and the curing behavior of SMC compression molding in detail.