Dynamic and wave propagation characteristics of the regular hexagonal prism modular tensegrity structure

Tensegrity structure is one of the ideal structural form to realize modular assembly of large spacecraft. Understanding the dynamic characteristics of modular tensegrity structures such as natural frequencies, vibration modes and wave behavior is crucial for the successful deployment of spacecraft in space. In this paper, according to the engineering practice of spacecraft assembly, we choose a regular hexagonal tensegrity structure module, and establish the dynamic model of tensegrity structure based on Lagrangian equation by finite element method and node coordinate vector. Subsequently, the natural frequencies and vibration modes of the modular tensegrity structure during the expansion process are analyzed. It is found that as the number of modules increases, the natural frequency tends to decrease and the torsional mode is more likely to occur. In addition, a comparison is made between the isotropic solid circular plate structure and the tensegrity structure, focusing on differences in modes and frequencies. The influence of self-stress on the modal characteristics and natural frequencies of tensegrity structures with varying numbers of modules is also investigated. Furthermore, according to the Bloch's theorem and the dynamic model, a wave propagation model for the tensegrity structure module units is established, from which the band structure and group velocity are derived. By comparing these results with the wave propagation paths obtained from numerical simulations of the large space tensegrity structure, it is demonstrated that the wave behavior of the large space tensegrity structure can be obtained by analyzing the wave characteristics of the module unit. Moreover, it is revealed that the regular hexagonal prism tensegrity structure exhibits difficulty in transmitting transverse waves and possesses a unique wave propagation directionality.