Mechanical properties and fatigue damage–failure mechanisms of T300/EM119 composite laminates

Abstract To investigate the mechanical behaviour of T300/EM119 composite laminates, [±45°] and [0°/90°] layups were subjected to quasi-static tensile and tension–tension fatigue testing, and a residual-strength model was constructed from the measured data. Fatigue fracture morphologies were characterized by scanning electron microscopy, and a finite-element model was employed to simulate fatigue life and the progression of failure. The results indicate that the average ultimate strength of the [0°/90°] laminate was 599.2 MPa, which was substantially greater than the 219.6 MPa measured for the [±45°] laminate (an increase of approximately 173%). Fatigue failure was shown to result from a combination of fibre fracture, matrix cracking, interface debonding and delamination. Delamination damage and fibre breakage were found to be particularly pronounced in the [±45°] layup, which was attributed to the higher shear stresses sustained by that configuration. Predictions of fatigue life and dominant failure modes obtained from the finite-element simulations were in good agreement with experimental observations.