Morphing composite cylindrical lattices: modelling and applications

Morphing composites have the potential to significantly reduce the mass and volume of deployable space components, expanding the applicability of smaller spacecraft to interplanetary missions and beyond. In this thesis, the analytical modelling of the morphing composite cylindrical lattice is further developed from a one-dimensional model by including the transverse curvatures, membrane strains and thermal residual effects, to improve the applicability of the morphing lattice to deployable systems. To this end, the analytical model is utilised in the development of a deployable space boom and a new deployable toroidal lattice. The morphing composite lattice is a structure comprising helical strips of carbon fibre composite, bound to a cylindrical shape. By tailoring the manufacturing parameters of the composite strips, the lattice is capable of morphing from a compact stowed shape to an extended deployed shape and any configuration in-between. In this work, the modelling of the lattice is enhanced by including the transverse curvature and membrane strains in the calculation of the stability landscape. The new formulation is capable of modelling lattice strips of arbitrary width that use symmetrical laminates. Further improvements include the addition of thermal strains and curvatures that develop during the cool down after curing at an elevated temperature. These thermal components have the potential to significantly alter the stability landscape of the lattice. This model was subsequently used to develop a thermally actuating lattice that is stowed at room temperature and self-deploys at 120°C. The accuracy of these models is verified through comparison with both finite element modelling and experimental testing. The developed model is then used to design two lattices for use in a deployable space boom. This boom weighs only 0.4kg and morphs from a compact 1U (1000 cm3 ) form factor, to an extended length of 2m. The lattices of the boom are tested in deployment force and bending experiments, which correlate well with numerical models. Finally, a new type of morphing lattice has also been developed that deploys along a toroidal path, rather than a straight one. It achieves its unique deployment path by the tailoring the pitch of the lattice fasteners. A numerical model of the curved lattice is developed to predict the stability landscape, which is verified by comparison with experimental testing.