Modal characteristics of the mirror-assembled six-bar rotational tensegrity module

Tensegrity structures are considered ideal candidates for the modular assembly of large spacecraft. Designing high stiffness tensegrity modules and analyzing their dynamic behavior are crucial for the successful deployment of spacecraft in orbit. In this study, a mirror-assembled six-bar rotational tensegrity module with diagonal cables is proposed, tailored for spacecraft assembly. The internal force distribution of the module is first obtained using a stiffness-matrix-based form-finding method, followed by a Lagrangian finite element dynamic analysis to investigate its modal characteristics before and after mirror assembly, with comparisons made to conventional six-bar rotational tensegrity modules. The results show that adding diagonal cables can optimize the internal force distribution and provide geometric constraints. After mirror assembly, the modules form a self-equilibrated structure dominated by material stiffness, which increases the stiffness and fundamental frequency. Furthermore, by varying the tilted and torsion angles, the modal characteristics of modules under different geometric parameters are explored, revealing the sensitivity of natural frequencies and mode shapes to changes in internal force and geometry both before and after mirror assembly. Based on these findings, the module with the highest fundamental frequency is selected to form one-dimensional (1D) and two-dimensional (2D) arrays of multi-module tensegrity structures. The dynamic behavior of these assemblies is investigated and compared with corresponding homogeneous structures, showing that as the number of modules increases, the dynamic characteristics of the multi-module tensegrity structures increasingly resembles that of the equivalent homogeneous system.