Nonlinear elastic buckling of ultra-thin coilable booms

This paper presents a study of the elastic buckling behavior of Triangular Rollable And Collapsible (TRAC) booms under pure bending. An autoclave manufacturing process for ultra-thin composite booms is presented and the behavior of three test samples is investigated experimentally. Two regimes are observed, a pre-buckling regime and a stable post-buckling regime that ends when buckling collapse is reached. The buckling collapse moment, marking the end of the stable post-buckling regime, is typically four times higher than the initial buckling moment. A numerical simulation of the boom behavior with the Abaqus finite element package is presented and all of the features observed experimentally are captured accurately by the simulation, except buckling collapse. The numerical model is also used to study the effect of varying the boom length from 0.3 m to 5.0 m. It is shown that the pre-buckling deformation of the flanges under compression leads to a constant wavelength lateral-torsional buckling mode for which the critical moment is mostly constant across the range of lengths.