Jérôme Quirant

Designing tensegrity systems: the case of a double layer grid

Abstract Tensegrity systems are innovative strut and cable systems used in Civil Engineering. Their lightness and the impression of transparency they convey represent new sources of inspiration for architects. Nevertheless, their conception and their design are not easy insofar as these systems are reticulate, spatial and self-stressed. In this article we set out to present the different stages of the conception and the design of tensegrity systems. The study of the selfstress, the choice of its level, the design of the elements and the study of the sensitivity to manufacturing element errors are the different subjects described. We will then present the concrete case of a double layer grid of 81 m 2 area.

Selfstressed Systems Comprising Elements with Unilateral Rigidity: Selfstress States, Mechanisms and Tension Setting

Selfstressed reticulated systems have given rise to many studies in the past. However, the theoretical studies undertaken were based on the assumption that their components had bilateral rigidities when, in fact for systems with elements as cables (tensegrity or cable-strut systems) this hypothesis is not valid any more. We propose here to extend the methods of research of the selfstress states or the mechanisms for such systems. Then we can at the same time: choose the relevant selfstress states verify that cables do not induce unilateral mechanisms optimize the number of active elements for the tension setting of the system.

Conceptual Design and Analysis of a Deployable Structure with Flexible Joints

The conceptual design of a self-deployable structure with flexible joints is presented in this paper. Joints store elastic energy in the folded, prestressed position and allow deployment until they are stopped by tendons. A study on a wire rope joint is first presented to determine its mechanical behavior with experimental, theoretical, and numerical approaches. An analysis is then performed on a bidimensional structure to propose the specific modeling of introducing prestress to the joints. The method is applied to a spatial system in an analysis that uses static equilibrium and kinematic deployment simulations. The results show good concordance among the different approaches.

Structural design and control of modular tensegrity structures

Tensegrity systems are self-stressed reticulate structures, composed of a set of compressed struts assembled inside a continuum of tendons. This principle can be at the origin of large, lightweight and transparent structures. In practice, a few structures of this kind were built, partly because they are very demanding in design and analysis. In the wish to contribute to the development of practical structural applications, we propose in this paper a design procedure that combines form-finding and structural dimensioning under static load. To optimise the behaviour in the dynamic domain, we present a general methodology suited for the control of the first vibration modes. The case of a modular tensegrity footbridge is taken for application, taking into account different materials.

Behavior of a Double-Layer Tensegrity Grid under Static Loading: Identification of Self-Stress Level

AbstractThe determination of the state of internal stress is important to define the rigidity of a tensegrity structure and its stability. Several methods can be used; some are based on direct measurements of the forces in the elements, but are not easily transferable to a real structure. The authors opt for indirect measurement techniques, which seem more appropriate for implementation on-site. One can consider the vibratory analysis of the elements, the vibratory analysis of the whole structure, or the analysis of the structure’s behavior under static loading. Here, the node displacement fields of a tensegrity structure in different states of self-stress under several strategies of static loadings is studied by comparing the measurement obtained by a tachometer with simulations. The aim of this work is to show the feasibility of a displacement field to identify the state of self-stress by this analysis. It is shown that under certain conditions, plans can be made to replace the direct measurement of the...

Interactive Dynamic Design and Analysis of Tensegrity Systems

In this paper, an implementation of the discrete element method is presented with applications in interactive design and dynamic non linear analysis of tensegrity systems, a class of lightweight reticulate space structures. These systems are simulated efficiently using an explicit time integration scheme coupled to a 3D visualization interface, which brings the possibility to interactively model a structure, to follow its evolution in real time and to perform advanced structural analysis. To validate and justify this particular approach in the case of tensegrity systems, a static analysis comparison with other structural analysis softwares is carried out on a representative example. The benefits and versatility of the method are further illustrated through simulations of planar and deployable structures.

Study and construction of a pentagon-based tensegrity ring

ABSTRACT Tensegrity rings are composed of strut circuits and based on straight prism geometry. Recently, authors developed a general study for this kind of structure and discovered their ability of folding. In this paper, we present our recent studies on the pentagon-based tensegrity ring from a mechanical, kinematical and experimental point of view. In term of theoretical study, numerical simulations are carried out. We analyse the influence of the self-stress level and element stiffness (cables and struts) on the global system. In matter of experimentation, we present design of our first human-scaled prototype which provides a remarkable lightness. Finally, we describe the folding of this system with a comparison between experiments and numerical simulations.

Etude de la déformée d'une grille de tenségrité pour l'identification de son niveau d'autocontrainte

ABSTRACT We study the possibility to use the measurement of the displacement fields of the nodes of a tensegrity structure under static loading to obtain a new method for the identification of its self-stress state. We try to determinate the correlation between the precision of this identification and the precision of the measure. With a tacheometer we obtain a precision of identification as good as the standard method using efforts measurements.

L'autocontrainte dans les systèmes de tenségrité

ABSTRACT Tensegrity systems are innovative systems, whose stiffness only results from an initial state of stresss, without external loading: selfstress. Their use as civil engineering constructive systems requires a deap knowledge of the compatible selfstress states, that they can accept. In response to this requirement two methods are submitted. First on, so to say geometric method, is based on the topology of the structure and the know of the designer. It introduces the concept of local selfstress state. The second one, a sthenic method, defines the partial selfstress states.

Towards Tensegrity Systems Design

Tensegrity systems are innovative systems in the field of Civil Engineering. Architects have been spurred on by their light weight and their apparent transparency. “A tensegrity system is system in a stable self equilibrate state comprising discontinuous compressed components inside a continuum set of tensioned components”.