Open Access

Florian Wittemann, Alexander Bernath, Nils Meyer, Luise Kärger

• Injection Molding is one of the most important processes to manufacture short fiber reinforced composites. During mold filling the fibers orientate depending on the flow field. The final fiber orientation influences the thermo-mechanical behavior of the part. During the holding stage, the matrix solidifies from fluid to solid, having crucial impact on the mechanical attributes and causing thermal and chemical shrinkage. The combination of these effects leads to residual stresses and warpage of the injection molded part, which may lead to dysfunctionality and waste production. One strong tool to minimize warpage in an early stage of part design is process simulation. Based on a virtual prediction, tool correction cycles, dysfunctional parts and therefore costs and production energy can be reduced. However, such prediction models need adequate material and process modeling, accounting for the anisotropic and thermo-visco-elastic material behavior. This work presents an approach to modelInjection Molding is one of the most important processes to manufacture short fiber reinforced composites. During mold filling the fibers orientate depending on the flow field. The final fiber orientation influences the thermo-mechanical behavior of the part. During the holding stage, the matrix solidifies from fluid to solid, having crucial impact on the mechanical attributes and causing thermal and chemical shrinkage. The combination of these effects leads to residual stresses and warpage of the injection molded part, which may lead to dysfunctionality and waste production. One strong tool to minimize warpage in an early stage of part design is process simulation. Based on a virtual prediction, tool correction cycles, dysfunctional parts and therefore costs and production energy can be reduced. However, such prediction models need adequate material and process modeling, accounting for the anisotropic and thermo-visco-elastic material behavior. This work presents an approach to model warpage of short fiber reinforced phenolic parts, by a combination of a CHILE- approach for the matrix and orientation averaging of mean field homogenized properties to consider the fiber orientation. Fiber orientation, temperature and curing field are determined in a preceding mold filling simulation.…