Strength Prediction and Measurement in Model Multilayered Discontinuous Tow Reinforced Composites

摘要

The purpose of this work is to perform analytical modeling and experimentally produce idealizedcomposite laminates reinforced with high-modulus discontinuous-fiber tows to evaluate thetheoretical upper limits of tensile strength as compared to continuous fiber composites. The idealizedcomposite represents a staggered mosaic of prepreg tape strips of equal width and length. Threedimensionalanalysis was performed to evaluate the energy release rate of the possible damageaccumulation modes, such as tow delamination and splitting emanating from tape strip ends in plieswith different orientations. The effect of residual stress was also evaluated on the delaminationpropagation energy release rates as well as tow end crack formation loads. Failure mechanisms forunidirectional and quasi-isotropic laminates were established by comparing the calculated energyrelease rates for tows in different locations to the critical Mode II energy release for axial cracking inthe material system. Specially designed experiments were conducted to verify the failure mechanismpredictions and evaluate proposed design changes for strength increase in the discontinuous-fibertow reinforced composites.