Study on the Effect of Fiber Orientation on the Elastic Constants of Carbon Fiber Reinforced Polypropylene Composites

In order to predict the effects of different fiber orientations on the elastic constants of composites, this paper takes carbon fiber reinforced polypropylene composites as an example, and adopts the Mori-Tanaka method to establish the Random Volume Element (RVE) model of fiber composites with five different fiber orientations, namely, 0 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees, and investigates the effects of the fiber The effects of fiber orientation and fiber volume fraction on their elastic constants were investigated to obtain the required data by this method instead of experiment. By improving the Halpin-Tsai model, the value of the orientation factor was determined on the basis of the random orientation factor, and the original shape factor was modified to an exponential shape factor, the orientation degree factor was introduced, and finally, the relationship equations between the modified exponential shape factor and the volume fraction and orientation degree were obtained. The results show that for the same fiber orientation and volume fraction, the smaller the value of shape factor, the higher the elastic modulus. The fitting errors of the four values of elastic constants were also analyzed, and it was found that the improved Halpin-Tsai model could be used to predict the elastic constants of carbon fiber-reinforced polypropylene composites in a certain range, thus providing a method to study the prediction of the elastic constants of composites by fiber orientation.