Coupling of flow simulation and structural analysis for glass-filled thermoplastics

In the automotive industry, glass-filled thermoplastics are used in air intake manifolds, radiator tanks, and many other parts. Plastic parts have many advantages over metal parts including mass, design flexibility and parts consolidation. However, widespread application of glass-filled thermoplastic materials has been limited in many cases by the inability to accurately predict performance and durability. Fiber-filled injection-molded parts contain complex fiber orientation patterns. This fiber orientation state affects material properties including elastic modulus and strength and part properties including shrinkage and warpage. Tremendous amounts of time and money can be saved if one can predict the moldability and mechanical properties of a part at the design stage. In this work, we present a method where commercially available injection molding and structural analysis software may be coupled together with appropriate material property data to improve prediction of structural performance for parts molded from short glass fiber-filled plastics. In addition, we compare the experimental and predicted performance based on simple equations and complex finite element calculations. Two major conclusions may be drawn from this work. In general, the assumption of geometric nonlinearity must be made. Also, an orthotropic material model is generally more robust and accurate than an isotropic analysis. Polym. Compos. 25:343–354, 2004. © 2004 Society of Plastics Engineers.