Study On Forming Process Of Long Glass Fiber Reinforce Polypropylene Composites

The lightweight of vehicle body has a great significance for the sustainable development of automotive industry, with the increasingly serious energy and environment problems, the application of composite materialas as an effective way of lightweight has been paid more and more attention. Compared with the traditional thermosetting matrix composites, long glass fiber reinforced polypropylene composites(LGFRPP) is cheap and environmental, and its mechanical properties is more better than the short glass fiber reinforced composites, so the application of it in vehicle body has been expanding from the interior parts to the load bearing parts. Hot forming is widely used for shaping LGFRPP, it has high production efficiency and good dimensional accuracy. Focusing on improving the mechanical properties and the quality of the molded parts, a systematic study is made on the forming process of LGFRPP in this paper, main contents and innovations include:In order to develop the mechanical performance of LGFRPP molded part, four processing parameters including preheating temperature, preheating time, molding pressure and pressure holding time were studied by using quadratic regression orthogonal rotation tests and response surface method. Response surface models of tensile strength and flexural strength are constructed, importance of the effects of factors is ordered by ANOVA, single factor effect and interaction effect are analyzed, optimized process parameters are got by NSGA-II.Applying LGFRPP into vehicle fender, improve the traditional mold design, and a complete set of process plan is developed including preheating temperature, pressure, compression speed, compression moment and holding time. Reasonableness of the processing parameters setting in this paper is detected by mechanical performance tests of the vehicle fender, at last, some quality defects are summarized and analyzed, and the corresponding solutions are present.The results indicate that the optimal combination of process parameters obtained by considering the interaction among multiple factors can make the mechanical properties of molded parts to further improve, applied it into the engineering practice, mechanical properties and surface quality of the fender can reach a higher level, the vehicle fender which be developed can meet the requirement of lightweight. The results and the method presented in this paper have much important theoretical significance to applied LGFRPP into the structure parts.