Residual strength of laminated composites after impact

Abstract

This article deals with the residual strength assessment on completely as well as partially penetrated laminated composites due to impact loads by idealizing the damage locations as holes and cracks. Modifications are made in the inherent flaw model (IFM) of Waddoups, Eisenman, and Kaminski (known as the WEK model) to correlate the fracture data of laminated composites. For velocities above complete penetration, the residual strength is identical to the static strength of the laminated composite with a hole having the same diameter as the impacting particle. For this case, the inherent flaw length ahead of the notch is correlated with notched and un-notched strengths through fracture parameters. For the case where the impact velocities are less than the penetration velocity, an empirical relation is proposed following the IFM for the residual strength in terms of kinetic energy of the impact. The adequacy of the modified IFM is demonstrated through comparison of fracture analysis results with tensile, compressive, and impact fracture strength of laminated composites containing holes and cracks.