Fiber orientation due to processing and its prediction

Abstract

Fiber reinforced polypropylene (FRPP) is used as a structural material because of its high strength and stiffness to weight and cost performance. FRPP parts are usually manufactured by a conventional polymer processing method, such as injection molding. In injection molding, polymer melt is injected into mold cavities by applying high pressure. Fiber orientation is induced by polymer melt flow during mold filling. Fiber orientation causes the anisotropy of mechanical properties in molded parts. For example, when all fibers align in a given direction, the elastic modulus in the fiber direction will be much larger than that in the perpendicular direction. Also, fiber orientation is a main reason of warpage of FRPP molded parts. Therefore, the prediction of fiber orientation is very important to control fiber orientation and prevent warpage in a design stage. Computer simulation can be used to predict fiber orientation in molded parts with three-dimensional complex geometry qualitatively in injection molding CAE(Computer Aided Engineering).