Predictions of the axial tensile property of the unidirectional composite influenced by microfiber breakage defects

This paper primarily investigated the effect of fiber breakage defects on tensile properties of the unidirectional composite (UD) using the numerical simulation method. Different kinds of fiber breakage defects were firstly proved to exist in the UD according to the sub-micro computed tomography images at the microscale level. A strict random uniform distribution hypothesis was then proposed to introduce fiber breakage defects into the composite. Numerous microstructural models within random fiber breakage defects were created with the Monte Carlo method to analyze the fiber breakage defect effect on the UD. The results show that the tensile modulus of the UD was reduced by 17% when the fiber breakage defect volume fraction was only 1%, which indicates the effect of this kind of defect was very significant. The fiber volume fraction, defect volume fraction and property all have influences on the decrease of the UD caused by the fiber breakage defect. Finally, we derived a mathematical model to calculate the tensile modulus of the UD based on the numerical results. The proposed mathematical model has an application on the prediction of the axial modulus of the UD or the fiber tow containing large numbers of fiber breakage defects in the composites with complicated structure.