Progressive damage in composite bolted joints via a computational micromechanical approach

In this paper, the pin-induced progressive damage of fiber-reinforced laminates employed in composite bolted joints is addressed. A nonlinear finite-element computational approach is developed, by describing the pin-based load transfer mechanisms via an incremental formulation that accounts for the unilateral contact between pin and laminate. The nonlinear incremental damage problem is faced via a multiscale strategy that couples: the laminate theory; the micromechanical bridging model for describing stress localization at the constituent scale within each ply comprising the laminate; a microscale biaxial strength criterion combined with a local material degradation rule. Some illustrative numerical applications are presented and discussed, highlighting the good agreement of the proposed results with available benchmarking experimental evidence, as well as providing quantitative indications on the influence of some model parameters.