An investigation of in-plane performance of ultrahigh molecular weight polyethylene composites

In-plane mechanical properties of an Ultra-High Molecular Weight Polyethylene based Dyneema^® composite were investigated at low strain rates. Low shear properties dominated the in-plane tensile response of the laminate through the lack of ability to transfer load between fibres, causing the strain state in the gauge region to be non-uniform. Averaged cross-sectional stress therefore underestimates the failure strength of the laminate, and because of this, the effect of laminate consolidation causing brinelling of fibres was unable to be quantified. The variation in strain across the specimen may however explain the difference in laminate stiffness and failure strain values in open literature. At higher strain rates, increased strength and stiffness of the laminate was found as the tensile response becomes more linear. ±45° tensile shear testing showed that results were highly non-linear and, as strains become larger, fibre rotation dominates testing results. In shear, higher consolidation pressures led to a small increase in maximum shear strength but had a negligible effect on laminate stiffness. Finally, an increased strain rate increased shear stiffness as well as shear strength.