Comparison of two progressive damage models for studying the notched behavior of composite laminates under tension

Two continuum damage models with different underlying assumptions are investigated to assess their predictive capabilities and limitations with respect to progressive intra-laminar damage in notched IM7/8552 CFRP composite laminates under tension. The recently modified continuum damage model, CODAM2, implemented in LS-DYNA is compared to a Ladevèze-based damage model, , implemented as a user-material model (VUMAT) in Abaqus/Explicit. Fundamental similarities and differences between the two models are first investigated by various single element simulation case studies before assessing their predictive capabilities at the more global coupon level. Over-height Compact Tension (OCT) tests with dispersed and blocked lay-ups as well as a wide range of scaled Center-Notched Tension (CNT) specimens are used to evaluate characteristic damage-related quantities such as strength, post-peak behavior and fracture energies. Experimental data are also used to further validate the two different meso-scopic damage models. The results of this study clearly demonstrate the layups, geometries and loading conditions that are suitable for applying intra-laminar damage models with confidence to this class of CFRP material system. Conversely, the study shows limitations of the continuum damage modeling techniques and suggests strategies that can be used to address these drawbacks.