Ballistic impact modeling of woven composites using the microplane triad model with meso-scale damage mechanisms

Existence of undulating fill and warp yarns in woven composite laminae introduces complex unit cell geometries and multi -scale interactions among the constituents. Due to these, the failure process involves various meso-scale constituent -level failure modes under complex loading scenarios such as ballistic impact. This can be challenging to model via conventional macro -scale damage tensor -based models. This challenge is tackled here via the adaptation of the previously developed multi -scale microplane triad model to ballistic impact of woven composites. The model can resolve meso-scale constituent level details (including yarn undulations) and predict not only the elastic constants of a woven lamina but also its fracturing behavior. In the present adaptation, only two damage laws are formulated, one for the fibers and one for the matrix. This enables the model to embody the correct values of the intralaminar mode I and II fracture energies of the woven lamina. The model is calibrated using constituent and lamina level test data, and then used to predict the ballistic impact behavior of a single plain -woven lamina under a wide range of projectile impact velocities. The model is demonstrated to predict very well the projectile residual (rebound and exit) velocities, the energy dissipation, the major failure modes of the lamina and the corresponding extent of damage, as well as the ballistic limit and deformation cone wave propagation speeds. The model's simple, conceptually clear architecture, and computational efficiency represent a major advantage compared to existing damage tensor -based models. The model is also extended to multi -layer thick section woven laminate impact, where the analyses consider both intralaminar and interlaminar failures. The predictions are found to be comparable to those from MAT162, a commercially available material model in LS-Dyna, with much better computational efficiency. Via detailed sensitivity studies, it is demonstrated that the mode I and II intralaminar fracture energies of the lamina are a crucial model input, necessary for accurate predictions of ballistic impact. Not knowing these can introduce significant uncertainty and therefore, their characterization is an absolute must. Finally, the optimal meshing considerations as well as the advantages and limitations of the microplane triad model are discussed.