Document Type : Dynamics, Vibrations, and Control
Authors
1
PhD Student, Aerospace Research Institute (Ministry of Science, Research and Technology), Tehran, Iran
2
Associate Professor, Aerospace Research Institute (Ministry of Science, Research and Technology), Tehran, Iran
Abstract
Tensegrity structures, characterized by their high stiffness-to-mass ratio and deployable capabilities, represent a promising solution for applications such as support structures. This paper explores the extraction of dynamic equations, form-finding, and geometric optimization of a tensegrity support structure designed for a planar antenna featuring a central ring and six petals. The nonlinear dynamic equations of the system were derived utilizing the Lagrangian approach and Finite Element Method, while the form-finding of the structure was achieved through a force density approach. For optimization, support structures with various configurations—maintaining a constant height and outer diameter while varying the curvature of the upper surface—were designed and optimized by altering the diameter of the middle ring. To enhance the accuracy of the optimization process, a hybrid optimization method was employed to finalize the geometry of the support structure, with the objectives of minimizing mass, increasing stiffness, and enhancing natural frequency. This hybrid optimization process, which integrates genetic algorithms with nonlinear constrained optimization algorithms, constitutes a novel contribution of this research. To assess the strength of the support structure, both free and forced vibrations of the system were analyzed regarding natural frequencies, mode shapes, deformation, nodal displacement, and internal member forces. The results affirm the improved vibrational performance of the structure following optimization and illustrate the advantages of utilizing feedback from vibrational analysis in finalizing the geometry, alongside a deeper understanding of dynamic behavior.
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