Experimental investigation of failure process in compressed channel-section GFRP laminate columns assisted with the acoustic emission method

The experimental investigations of thin-walled channel section columns subjected to static compression are described. The columns under consideration were made of eight layers of a glass/epoxy unidirectional prepreg tape, with the autoclaving technique. Six different symmetrical layer arrangements were taken into account. The tests were performed on a Zwick Z100/SN3A universal testing machine with special self-aligning grips. The columns under investigation were loaded with the force values from zero to the maximal load destroying the profile, which allowed one to observe the column behaviour till its collapse. The strain gauges measurement technique was employed to determine the equilibrium paths, the buckling loads and the post-buckling behaviour. During all the tests, AMSY-5 AE equipment made by the Vallen company was applied to detect acoustic emission phenomena. The acoustic emission method allowed to investigate the behaviour of composite structures in the phase prior to their collapse. The results of the experimental investigations were employed to validate the proposed FE model in order to analyse the post-buckling behaviour and to determine the failure load with the well-known failure criteria.