LOW-VELOCITY IMPACT DAMAGE IN COMPOSITE SANDWICH BEAMS

Impact damage in sandwich beams consisting of graphite/epoxy face shee ts and Rohacell foam core was investigated. Low velocity impact tests were conducted to investigate damage mechanisms and damage modes in th e face sheet and the core. The major modes of failure included local ' yielding' of the core, matrix cracking and delamination in the face la minate. A finite element analysis was performed to predict the onset o f matrix cracking composite laminate using the maximum principal stres s failure criterion. Subsequent delamination was analyzed using fractu re mechanics. In the analysis the core was assumed to be elastic-plast ic. The predicted delamination crack length agreed very well with the experimental data.