An Investigation of Inner Flange Buckling in Furlable Composite Booms

The triangular rollable and collapsible (TRAC) boom is an attractive architecture for deployable spacecraft structures due to its minimal flattened height-to-deployed stiffness ratio. A challenge for TRAC booms however is the development of a buckling mode that occurs (on the inner flange) when furling the boom around a hub for stowage. In this research, the buckling mode was found to be sensitive to boom flange length and the composite flexural stiffnesses dictated by the laminate materials, fiber orientations and ply stacking sequence. Finite element studies were performed to investigate the influence of flange arc length and composite layup on critical stresses and strains prompted by the buckled wave. Longer flange lengths resulted in higher strains but could be offset through modifications to the laminate architecture allowing for larger booms to be packaged without increasing the minimum stowage (hub) diameter. The analysis model was validated through experimental furling tests and successful correlation between the simulation strains and experimental strain gages.