The microbuckling failure of Dyneema^® composites under compression

Two grades of Dyneema^® composite laminates with the commercial designations of HB26 and HB50 were cut into blocks with or without an edge crack and compressed in the longitudinal fiber direction. The cracked and uncracked specimens show similar compressive responses including failure pattern and failure load. The two grades of Dyneema^® composites exhibits different failure modes: a diffuse, sinusoidal buckling pattern for Dyneema^® HB50 due to its weak matrix constituent and a kink band for Dyneema^® HB26 due to its relatively stronger matrix constituent. An effective finite element model is used to simulate the collapse of Dyneema^® composites, and the sensitivity of laminate compressive responses to the overall effective shear modulus, interlaminar shear strength, thickness and imperfection angle are investigated. The change of failure mode from kink band to sinusoidal buckling pattern by decreasing the interlaminar shear strength is validated by the finite element analyses.