Mechanical Properties Study Of Glass Fiber Reinforced Microcellular Plastic Injection Molded Thin-walled Structures Based On Multi-scale Method

Glass fiber reinforced resin matrix composites are widely used in various industries because of many advantages such as high strength, light weight, insulation temperature resistance, corrosion resistance, etc. However, it often brings great challenge to research workers while showed excellent mechanical properties due to its complex internal structure. Nevertheless, it provides the research of mechanical properties of the composites a new train of thought. Many studies on mechanical parameters of unidirectional continuous fiber reinforced composite show that homogenization theory often gives a good prediction compared with other methods.First, this paper takes a long glass fiber reinforced injection specimen as the research object, and use the homogenization theory to establish the RVE(Representative Volume Element) model based on the cross section’s microscopic observation of glass fiber distribution. On this basis, elastic mechanical properties of the composites were obtained by applying numerical simulation on the RVE, and then compared with the experimental data of injected spline tension. It explores the feasibility of using the homogenization theory to predict the elastic mechanical properties of non-continuous long glass fiber reinforced polymer. At the same time, the configuration rules of glass fiber reinforced structure and foaming materials were studied, and then the elastic modulus and Poisson’s ratio of each components as well as the influence of glass fiber orientation etc. were analyzed in parametric.Subsequently, it takes a specimen which cut from microcellular plastic injection molded door plank as the research object in this paper, and use the homogenization theory to establish the RVE model of skin layer and foam layer based on the microscopic observation of cross section structure, then get the elastic parameters skin layer and foam layer separately by combining the homogenization theory with ABAQUS simulation. After that, this paper analysis the linear elastic performance of glass fiber reinforced microcellular plastic injection molded PP structure specimen according to the solid elements and shell elements flexural simulation successively, and then compares it with the flexural test results. In addition, this paper preliminary studies the nonlinear properties of glass fiber reinforced microcellular plastic injection molded PP structure on the basis of shell elements model, and compares it with the flexural test curve, so that fits out mechanical parameters for simplified two-stage stiffness of foam layer.In conclusion, the research shows that homogenization theory is validated to predict the equivalent elastic mechanical properties of discontinuous glass fiber reinforced moldings in engineering. Furthermore, it is significant to provide the scientific basis for the analysis of structure service performance. Besides, it is more reasonable to base on the new finite element model built by adding polypropylene at both ends of glass fiber than on the traditional one which applied on continuous fiber reinforced composites. Furthermore, we can get an elastic modulus with higher reliability by using ABAQUS analysis foam layer. In addition, it is more accurate and flexible to base on shell element model than solid one.