Propagating Instabilities in Coilable Booms

Coilable booms consisting of thin composite shells bonded along a common edge are being considered for novel deployable spacecraft structures. These booms have many desirable features such as light weight, high stiffness, and high packaging efficiency, but this successful realization poses new challenges. In this paper, we study the propagating buckles that have been observed in the transition region between the coiled and deployed parts of the booms. These buckles, which can cause local stress concentrations and material failure, are typical of booms with built-up sections. They do not occur in tape springs. We investigate the root cause for the propagating buckles and discuss the possibility of limiting the buckle growth by increasing the material shear modulus.