Damage Mechanics Formulation of the Crack Evolution Process in Composite Laminates under Plane Stress Conditions

An analytical model to predict the constitutive behavior of laminated composites with cracking layers is developed in the framework of continuum damage mechanics. A new concept that a cracked lamina can be replaced with an equivalent uniform work-softening layer is proposed. With this new concept, the constitutive equations for a cracking layer are constructed according to the modern plasticity theory. A lamina damage surface, a threshold of crack evolution, is defined in the stress space, and the constitutive equations for a cracking layer are constructed along with the associated flow rule. Furthermore, the derived constitutive equations for a cracking layer are applied to the classical lamination theory to describe laminate constitutive behavior in the cracking process The validity of the constitutive model formulation is also verified comparing the analytical predictions to experimental results for some laminate configurations.