Non-linear analysis of the postbuckling behaviour of eccentrically compressed composite channel-section columns

Abstract

This analysis investigates short thin-walled channel-section columns made of CFRP laminate. Columns with four multi-ply composite layups were tested, each layup having 8 plies symmetric to the midplane. The columns were subjected to compressive loads, including an eccentric compressive load applied relative to the centre of gravity of their cross-section. The study involved performing a nonlinear analysis of the structures with implemented geometric imperfections that reflected the first buckling mode. The nonlinear analysis was conducted using the Tsai–Wu criterion to determine effort of the composite material. The computations were run until the critical parameter in the Tsai–Wu criterion was reached, which made it possible to describe the failure initiation mechanism in the composite material. Experiments were conducted to detect first signs of damage to the composite material by the acoustic emission method (AEM). Experimental results were used to determine postbuckling equilibrium paths of the numerical models. The equilibrium paths were then compared with the experimental characteristics of real structures. The numerical and experimental results showed satisfactory agreement. That confirmed that the developed numerical models were suitable for estimating the postbuckling behaviour of composite structures depending on the amplitude of compressive load eccentricity.