Prediction of thermo-mechanical properties for compression moulded composites

We present a method to determine the thermo-mechanical properties of compression moulded composite parts. The flow-induced fiber orientation is first calculated by numerical simulation, and the resulting orientation state is used as input in a micromechanical model that predicts the thermo-mechanical properties of the part. A two-step homogenization scheme based on the grain model approach is followed. First, the properties of a reference composite with aligned fibers are estimated by means of a mixture rule between the upper and lower Hashin-Shtrikman bounds (derived by Willis). This method is in agreement with the Mori-Tanaka estimates for moderate concentrations, and gives better results for higher concentrations. Next, the properties of the composite are obtained by averaging several reference composites with different fiber directions. An example of a 3-D compression moulded composite part is analyzed and the results are discussed.