Delamination and kink-band failure of pultruded GFRP laminates under elevated temperatures and compression

Compression experiments were conducted on slender glass fiber-reinforced polymer (GFRP) laminates at different temperatures in the elevated range. Experimental buckling loads, lateral second-order deformations, and shear strength decreased with increasing temperature until stable values were reached at a much lower level in the leathery material state. The resin-dominated bending stiffness decreased at a higher rate than the fiber-dominated compressive stiffness. Global buckling followed by a delamination failure during the post-buckling process was observed for temperatures below 180 °C, while pre-buckling kink-band failure occurred when the temperature increased to 220 °C. Recently proposed thermomechanical models were further validated and enabled the changing failure mode and associated Tresca and kink-band shear stress and strength conditions to be modeled.