Reticulated spatial systems in tensegrity state. Recent developments

Spatial reticulated systems in a state of tensegrity belong to the class of lightweight structures. Their structural composition is associated with a state of self-stress that requires a search for a form compatible with its realization. They represent a generalization of "prestressing" to spatial structures. They are characterized by a strong coupling between morphology and mechanics.

In the field of construction, due to their apparent complexity, the applications of this type of system have not come naturally to designers, but a few projects have demonstrated their feasibility. They are relevant in sometimes unexpected applications, such as in the medical field, but also in that of controllable systems. Their ability to be modified geometrically without removing components, and to be deployed rigidly without adding components, is a decisive factor in progress in the field of foldable unfoldable structures: they represent an innovative solution compared with other existing modes.

To meet the challenges associated with their specificity, several developments were necessary. New morphological configurations have been proposed. In particular, cells with irregular geometries and a high number of components are proving useful for modeling the cytoskeleton of endothelial cells. The definition of a tensegrity ring and the study of its foldability have led to proposals for deployable footbridges; the very principle of ring assembly is not restricted to horizontal systems, and vertical or even inclined towers can be built with tensegrity rings. Other projects are under study for two- and three-dimensional global morphologies.

The existence of self-tensioning, and the possibility of using sensors and actuators, make it possible to control tensegrity systems, either to control their deployment, or to modify their mechanical characteristics to meet frequency requirements. These advances have been made possible by the simultaneous development of control software. These qualities are now being fully exploited in the design of robots used for both space conquest and terrestrial applications. The design of reticulated space systems is now facilitated by numerical models integrating the coupling between morphology and mechanics, models based on procedures such as dynamic relaxation: the designer can literally model his project in interaction and, for example, modify the curvatures of an arch while respecting the possibility of the existence of self-stressing states.

Due to their characteristics, space reticulated systems in a state of tensegrity open the way to controllable constructive systems with evolving morphology. They are perhaps the forerunners of civil engineering in Space.

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