Influence of manufacturing process technology on buckling behaviour of thinwalled, GFRP columns with a square cross-section

Abstract

In this study, static compression of thin-walled, composite columns with square cross-section is presented. The influence of heat transfer during the manufacturing process of thin-walled column on the behaviour during compressive load has been investigated. Two series of the columns made of GFRP laminate with symmetric layup [45/-45/45/-45]s were manufactured using the autoclaving technique. To check the way of heat transfer during the curing process the two different methods of retaining and giving off heat from the produced element during its cooling in the autoclave process by using other process durations and mandrels were used. It is a well-known fact that different curing speeds and cooling rates affect the distribution of residual stresses inside the structure that could have a significant impact on its future structural performance. In case of this study, the target of these operations was to verify how the manufacturing process and generated in this process residual stresses are affecting buckling and postbuckling behaviour of the structures. Therefore, manufactured in this manner two series of four specimens were experimentally tested. The static compression tests were performed on Instron universal testing machine employing additionally a contactless digital image correlation system GOM ARAMIS ®. Additionally, the numerical model has been developed and used to perform FEM analysis including cooling process (manufacturing procedure simulation) and compression test (operating load simulation). TheThe obtained load-deflection and load-shortening function enabled to determine critical loads and postcritical stiffness and verify how different distribution of residual stresses is affecting the stability of such columns.