Enhancing Longitudinal Compressive Properties of Unidirectional FRP Based on Microbuckling Compression Failure Mechanism

In this study, a new methodology to improve the longitudinal compressive strength and modulus of ultra-high molecular weight polyethylene (UHMWPE) fiber-reinforced epoxy resin matrix is developed. The proposed method involves wrapping a UHMWPE fiber bundle with a poly-p-phenylene benzobisoxazole fiber filament using a winding method, and using these bundles to fabricate unidirectional UHMWPE fabric. UHMWPE/epoxy composites were fabricated using vacuum-assisted resin-transfer molding (VARTM), and the compression properties of the composite were evaluated and compared to investigate the effect of the filament wrapping. Improvements in the compressive modulus were achieved for filaments wound with applied tension, and when increasing the filament-winding spacing; however, the compressive strength decreased with an increase in the filament-winding spacing. Results obtained confirm that fiber microbuckling failure occurred in the composite under longitudinal compression, and that inhibiting the buckling length of the fiber improved compressive properties. These results may be useful when designing the mechanical properties of fiber-reinforced polymer composites.