Local anisotropy analysis based on the Mori-Tanaka model for multiphase composites with fiber length and orientation distributions

A local anisotropy takes place in filler reinforced polymer composites due to the high aspect ratio of inclusions, which influences the mechanical or thermo-mechanical performances of the final products such as dimensional stability, flowability, toughness, and strength. It is of importance to investigate the local anisotropy and the relationship between the anisotropy and the mechanical strength of composites. Here, we visually represent the microstructural anisotropy of the multiphase polymer composites composed of talcs and glass fibers based on the Mori-Tanaka approach. The internal structures of the composites are observed by using an X-ray micro-tomographic scanning method to characterize fiber length and orientation distributions. The fiber length distributions are fitted to the Weibull distribution statistical function. It is confirmed that the fiber orientation distributions should also be taken into account to predict the accurate theoretical elastic moduli and local anisotropy of the composites. The effective elastic moduli of the composites with the fiber length and orientation distributions are estimated based on the Mori-Tanaka model.