Nonlinear viscoelastic micromechanical analysis of fibre-reinforced polymer laminates with damage evolution

A micromechanical model of unidirectional fibre-reinforced polymer laminates under off-axis loading is analyzed using finite element method. A three-dimensional periodic unit cell is established with the matrix described by a nonlinear viscoelastic model and the fibre by an elastic one. Matrix cracking is modeled by smeared crack method which permits a crack description in terms of stress-strain relations and stiffness reduction in particular orientations. The micromechanical analysis features material nonlinearity, damage initiation and growth, and multiaxial loading. Numerical results reveal the local and global response of the laminate including the damage mechanism. The predictions are in good agreement with the test results performed on a similar composite system.