Flexural Performance of Hybrid Discontinuous Fiber Composites Made of Repurposed Aerospace Prepreg

Abstract

The flexure properties of Discontinuous Fiber Composites (DFCs) made from repurposed aerospace prepreg are investigated. In this study, two platelet sizes with varying length and the same width are used. Three thicknesses are investigated along with hybrid laminates, which combine DFCs and unidirectional (UD) and textile tapes. The study showed that by increasing platelet length, the flexure properties increased by, on average, 37%, but the Coefficient of Variation (CoV) also increased by, on average, 47%. However, as the thickness increased the CoV decreased by, on average, 25% while the flexure properties did not change. By adding continuous fiber plies, the average flexure properties increased by 29-67%. However, there were cases where adding these plies increased the CoV of the modulus. This is due to fiber waviness caused by platelet motion during cure. This was mitigated by a precure routine and using a textile ply between the UD and DFC core. The precured and textile hybrids resulted in a lower CoV of the flexure modulus. On the other hand, the CoV of the flexure strength was always lowered by the addition of continuous fiber plies by 36-67%. A finite element model was developed which could match and predict the flexure modulus of DFC and hybrid specimen. The development of this model is of utmost importance to mitigate the need of extensive physical tests to validate parts made using DFCs. The experiments and computations showcase the excellent tunability of DFCs, and the immense potential this repurposing method has to reduce thermoset prepreg waste.