Predicting failure load of a non-crimp fabric composite by means of a 3D finite element model including progressive damage

Abstract

A mesoscopic scale 3D finite element model of its representative unit cell is used to study the progressive damage of a [0,90]n non-crimp fabric laminate under compressive loading. The tows of the unit cell have been generated with a straight finite element mesh, and the out-of-plane fibre crimp has been incorporated into the model by defining the mechanical properties of each element according to the actual direction of the fibres. The material properties degradation (MPDG) method has been used to study the damage evolution. Non-interactive criteria (Maximum Stress and Maximum Strain), and interactive criteria (Hashin and Puck), associated with failure modes, have been employed to determine the onset of the material degradation at the fibre tows. The progressive damage throughout the mesoscopic unit cell, from the load at which damage is initiated, until the load at which the failure of the laminate is predicted, has been analysed. The mechanism responsible for the failure of the laminate has also been identified. The numerical predictions of the failure stress and failure strain, for the considered failure criteria, are discussed and compared with experimental data obtained from direct compression tests on biaxial cross-ply NCF laminates. A satisfactory agreement between the numerical and experimental failure stress, failure strain as well as the compressive stress-strain curves has been obtained for the MPDG method when using Maximum Stress, Hashin’s or Puck’s failure criteria.