PREDICTION OF THERMOMECHANICAL PROPERTIES FOR COMPRESSION MOLDED COMPOSITES

We present a method to determine the thermo-mechanical properties of c ompression moulded composite parts. The flow-induced fibre orientation is first calculated by numerical simulation, and the resulting orient ation state is used as input in a micromechanical model that predicts the thermo-mechanical properties of the part. A two-step homogenizatio n scheme based on the grain model approach is followed. First, the pro perties of a reference composite with aligned fibres are estimated by means of a mixture rule between the upper and lower Hashin-Shtrikman b ounds (derived by Willis). This method is in agreement with the Mori-T anaka estimates for moderate concentrations, and gives better results for higher concentrations. Next, the properties of the composite are o btained by averaging several reference composites with different fibre directions. An example of a 3-D compression moulded composite part is analyzed and the results are discussed. (C) 1997 Elsevier Science Lim ited.