Design of efficient lattice truss beams in bending and torsion for large-scale space structures

A rational analysis of the influence of geometric and material parameters on the triangular lattice truss beam’s performance is presented in this paper, along with a novel method for correlating static stiffnesses to natural frequencies in bending and torsion. Equilateral triangular cross-section composite lattice truss beams exhibit potential as the foundation for constructing large-scale space structures in the future. These truss beams are composed of several structural elements, each of which contributes to the overall structural behavior. To predict the overall structural performance of a lattice truss beam, it is necessary to estimate the impact of its members’ geometric and material properties on its stiffness and natural frequencies. The equivalent stiffnesses in bending and torsion are evaluated using finite element (FE) simulations with variations in the cross-section, material properties, location, and orientation of the individual composite tubes in the repeating unit of the lattice truss. As an efficient structure should be lightweight with high stiffness, the stiffness achieved for the linear mass distribution is taken as a comparison metric for the different truss configurations. A semi-analytical approach using established theories of solid mechanics is then adapted to compute the natural frequencies in torsion and bending with the equivalent stiffnesses obtained. These analytical frequencies are verified with those obtained from the finite element (FE) simulations. The demonstrated correlation between equivalent stiffnesses and natural frequencies allows them to be used interchangeably in the design of truss beams, thus reducing efforts.