Impact of the bars behavior on the design of soft tensegrities

Abstract

Soft tensegrity is a recent concept, which can be described as a prestressed assembly of soft cables in tension and bars in compression. In this paper, we investigate the impact of the bar behavior on the mechanical properties of a tensegrity. It is achieved through the change of bar material, from soft (e.g. silicone) to stiff (e.g. steel) materials. First, we show that it is possible to realize a self-supporting tensegrity where both cables and bars are made of soft material. Second, we highlight that the bar material impacts the isotropy of the tensegrity's stiffness matrix and the range of achievable stiffnesses. Last, we demonstrate that bar material has a significant impact on the precision of stiffness variation, when active elements are integrated in the tensegrity. From these effects, we extract design guidelines for the choice of bar material in a soft tensegrity.