Mixed micromechanics and continuum damage mechanics approach to transversecracking in [S,90(n)](s) laminates

The stiffness reduction in [S, 90(n)](s) laminates due to transverse cracki ng in 90-layers is analyzed using the synergistic continuum damage mechanic s (SCDM) and a micromechanics approach. The material constants involved in the SCDM model are determined using the stiffness reduction data for a refe rence cross ply laminate. The constraint efficiency factor, which depends o n the stiffness and geometry of neighboring layers, is assumed to be propor tional to the average crack opening displacement (COD). The COD as a functi on of the constraint effect of adjacent layers and crack spacing is describ ed by a simple power law. The crack closure technique arid Monte Carlo simu lations are used to model the damage evolution: the 90-layer is divided int o a large number of elements and the critical strain energy rate Gc having the Weibull distribution is randomly assigned to each element. The crash de nsity data for a [0(2)/90(4)](s) cross plan laminate are used to determine the Weibull parameters. The simulated crack density curves are combined wit h the CDM stiffness reduction predictions to obtain the stiffness versus st rain. The methodology, developed is successfully used to predict the stiffn ess reduction as a junction of crack density in [+/- theta /90(4)](s) lamin ates.