Using of tensegrity grid dynamic behavior to identify its self-stress level

• As one classically calculates the self-stress state of a tensegrity grid by measuring the forces in the elements of the structure, we present in this paper an innovative alternative method using dynamic behavior of the structure.
• We first determine numerically the influence of the self-stress state on the Eigen modes. Our simulations of these Eigen modes have been confronted and validated by results of experimental tests.
• We then determine the link between the identification of the self-stress state and the Eigen mode to underline the importance of the choice of this latter to obtain good results.

The structures of tensegrity are light structures of which stability is conditioned in a state of prestressing called self-stress. Work presented relates to a structure with double layer which is instrumented with gauges of deformation to determine the forces in the bars. The aim of work is to find the forces in the elements by indirect measurement for further in-situ applications when the bars instrumentations will be impossible. Here, we explore the possibility of using the measurement of the fields of acceleration of the nodes of a structure of tensegrity under dynamic loading in order to identify the self-stress state. We show the effect of the self-stress level on the modes of vibration of the structure to determine the correlation between the precision of this identification and the influence of the mode concerned. The results confirm the complex relation which exists between the Eigen-modes and the identification of self-stress state. The identification is generally more powerful for the first global modes which are impacted by all self-stress states than for the local modes which are often dependent only of one self-stress state.