Analysis of instability-related growth of a through-width delamination

SUMMARYWhen a laminated composite is subjected to compressive loads, adelaminated region may buckle. This causes high interlaminar stresses at thedelamination front and the delamination may grow. The effect of variousparameters on instability-relateddelamination growth was studied analyti­cally. The configuration studied consisted of a thick composite laminate witha single through-width delamination located near one surface. Both mechanicaland thermal loads were considered. All conclusions were based on the assump­tion that G r and G rr govern delamination growth. An approximate super­position stress analysis was developed which gives closed form expressionsfor GI and GIl' The simplicity of the analysis permitted examination ofnumerous configurations. Both G r and G Ir were found to be very sensitiveto delamination length and location through the thickness. The magnitude ofGI was also very sensitive to initial imperfection. Critical loads fordelamination growth were calculated based on three growth criteria. Largedifferences in the predictions highlight the need for a verified mixed-modedelamination growth criterion.