Surface quality and shrinkage of the composite bus housing panel manufactured by RTM

Resin transfer molding (RTM) process has been widely used in automobile industries, because products with large area can be manufactured easily with lower manufacturing cost than that of compression molding or hand lay up method. Although composite structures manufactured by RTM have light weight, good dynamic and impact characteristics, the low surface quality of composite structures made by RTM often hinders the adoption of composite automotive panels because parts made of glass fiber mat and unsaturated polyester often have shrinkage and warpage problems. To investigate the relationship between the shrinkage and the surface quality of composite part, in this work, the formation of surface contour line and the surface quality were measured experimentally with respect to stacking sequence and fiber volume fraction of glass fiber. Based on the results obtained, a real size composite bus housing panel was successfully manufactured.