DAMAGE GROWTH ANALYSIS OF LOW-VELOCITY IMPACTED COMPOSITE PANELS

Low velocity impact loading in aircraft composite panels is a matter o f concern in modern aircraft and can be caused either by maintenance a ccidents with tools or by in-flight impacts with debris. The consequen ces of impact loading in composite panels are matrix cracking, inter l aminar failure and, eventually, fiber breakage for higher impact energ ies. Even when no visible impact damage is observed on the surface at the point of impact, matrix cracking and inter laminar failure can occ ur, and the carrying load of the composite laminates is considerably r educed. The greatest reduction in loading is observed in compression d ue to laminae buckling in the delaminated areas. The objective of this study is to determine the limit loading capacity and the damage growt h mechanisms of impacted composite laminates when subjected to compres sion after impact loading. For this purpose a series of impact and com pression after impact tests were carried out on composite laminates ma de of carbon fiber reinforced epoxy resin matrix. Four stacking sequen ces representative of four different elastic behaviours were used. Res ults show that the compressive, after impact. failure stress is influe nced by the stacking sequence but a relatively independent strain to f ailure is observed. (C) 1997 Elsevier Science Ltd.