Abstract
Partially flat tape springs have been proposed as deployment booms that allow flat conductive elements to be embedded in the cross section. This paper presents an energy model that can predict the moment-rotation behaviour and second stable geometry of partially flat tape springs/booms. The energy model is implemented through Matlab using a constrained optimiser. The model is validated using a combination of analytical approaches and a Finite Element (FE) model. The energy model is in good agreement with previous literature for tapes with a uniform cross section radius. It is shown that the introduction of the flat section decreases the maximum snap-through moment of tape springs and increases the second stable coiled radius of booms. For a tape spring of uniform radius the snap-through moment is approximately 353 Nmm and 400 Nmm, predicted by the energy and FE model, respectively. The introduction of a 5 mm flat section, whilst maintaining the total arc length, results in a snap-through moment of 220 Nmm and 175 Nmm from the energy and FE model, respectively. For small deformations the energy model agrees well with the finite elements results.