Effect of covering filaments on the compression performance and failure mechanism of unidirectional fiber‐reinforced plastic

The effects of covering ultra‐high molecular weight polyethylene (UHMWPE) fibers with different types and spacings of filaments on the longitudinal compression properties of unidirectional UHMWPE fiber‐reinforced epoxy resin samples were investigated. UHMWPE fiber bundles covered with fiber filaments were prepared using a custom winding machine, and composites were subsequently fabricated by vacuum‐assisted resin transfer molding. Covering filament spacing was controlled by the warp speed. Compression testing of the resulting samples was performed and the fracture surfaces were examined by an optical microscope. The results showed that the compression strength and modulus of the unidirectional composites reinforced with filament‐covered bundles depended strongly on the compressive failure mechanism, which was decided by the type and spacing of the covering filament. Four kinds of filaments have positive effect for compressive properties of composites, for the basalt filament, the effect for improving compressive strength is best, the improving percentage is 18.4%. For the UHMWP and PBO filament‐covered UFRPs displayed considerable increases of compressive modulus, with improvements of about 36% and 45%. POLYM. COMPOS., 39:247–253, 2018. © 2016 Society of Plastics Engineers