Equivalent mechanical properties of tensegrity truss structures with self-stress included

Abstract

Due to the complex structure of tensegrity systems it is often hard to understand their behaviour and estimate their mechanical properties. As a result, they are rarely used in real engineering applications. The present paper focuses on the evaluation of equivalent mechanical properties of various tensegrity modules based on a continuum model. The aim of the applied model is to facilitate the identification and understanding of mechanical characteristics of tensegrities through their comparison with a continuum body with equivalent features. The model is built by assuming that the strain energy of an unsupported tensegrity module or structure is equivalent to the strain energy of a solid. The approach enables to estimate the influence of self-stress on deformation of the structure, identify the influence of cables and struts on the properties of the whole system, determine equivalent mechanical characteristics, such as Young's moduli, shear moduli, Poisson's ratios etc., and conditions that limit their values. What is more, a qualitative as well as quantitative evaluation and comparison of mechanical properties for various tensegrity modules and systems is possible with the use of the applied technique. A comprehensive analysis of typical tensegrity modules with various elastic symmetries is presented. Using the adopted model, mechanical characteristics are determined and graphs of identified mechanical coefficients for five typical tensegrity modules are presented in relation to the self-stress multiplier and cable to strut properties ratio. The analysis can be useful for the development of extreme mechanical properties of smart tensegrity-inspired 2D or 3D lattices or metamaterials.