Damage mechanics approach to nonlinear behavior of FRP laminates with cracking layers

Abstract A damage mechanics model to predict the nonlinear behavior of laminated composites due to crack evolution is developed. We propose a new concept that a cracking layer can be replaced with an equivalent uniform work-softening layer. With this new concept, the constitutive equations for a cracking layer are constructed according to modem plasticity theory. A lamina damage surface, i.e. a threshold of crack evolution, is defined in the stress space of each lamina, and the constitutive equations for a cracking layer are constructed by applying the defined damage surface to the associated flow rule. Then, the derived constitutive equations for a cracking layer are introduced with classical lamination theory to predict laminate constitutive behavior in the damage process. Comparisons are made between the predictions and experimental results for some laminate configurations, and reasonable agreements are shown for all laminates. Keywords: Damage mechanicscomposite materialconstitutive equationmatrix crackingwork-softening