Buckling and Postbuckling of a Delaminated Composite Beam in Bending

A study was conducted to model the thin delaminated layer using the Elastica theory and investigate the postbuckling behavior for a delaminated beam under compression. Static tests were performed to understand the buckling and propagation behavior of 16-ply, laminated beams with a through-width delamination created by a polytetrafluoroethylene (PTFE) layer of 0.02 mm thickness and 40 mm length placed at the mid length of the beam between the second and third ply. A unidirectional plate made of M21-T800 carbon material was laid up and cured using an autoclave. An INSTRON-1332 servo-hydraulic machine with 10 kN load cell was used for loading application. The strain gauges and loading channel from the servo-hydraulic machine were connected to a SPIDER-8 data acquisition system which was attached to a PC. The specimens were also loaded through a four point bending fixture under displacement control.