Compression-after-impact test analysis of CFRP skin-stringer specimen by FEM using a zig-zag type cohesive zone model

A quasi-static indentation (QSI) test analysis equivalent to the low-velocity impact test and the subsequent compression-after-impact (CAI) test analysis of the carbon fiber reinforced plastics skin-stringer specimen were performed by FEM using interface elements considering the zig-zag cohesive zone model, which models delamination and matrix cracking. Damage propagation analyses were performed by the implicit method considering nonlinearity, such as materials, large deformations, and contact phenomenon. The numerical models were validated through comparison with experimental results, including the indentation load-displacement relationship and delamination area in the QSI test and the compression load-displacement relationship and strain-displacement relationships in the CAI test. Moreover, the effects of dents due to impact test and the initial imperfection were also examined.