Vibration Suppression in a Simple Tension-Aligned Array Structure

Tension-aligned structures have been proposed for space-based antenna applications that require a high degree of accuracy. The structure uses a compression member to impart tension on the antenna, thus helping to maintain shape and facilitate disturbance rejection. These structures can be very large and therefore sensitive to low-frequency excitation. A simple control strategy for tension-aligned structures is proposed, based on the concept of stiffness variation by sequential application and removal of constraints. The process funnels vibration energy from low-frequency to high-frequency modes of the structure, where it is dissipated naturally due to internal damping. A simple model for the arrangement is used to demonstrate the effectiveness of the control strategy. It consists of a curved beam modeled as a nonlinear elastica arch (the support structure), connected to an array of hinged panels (the antenna). Two methods for stiffness switching are investigated: variable stiffness hinges in the panels and variable stiffness elastic bars connecting the panels to the structure. It is shown in simulations that sequential application and removal of the constraints is an effective mechanism to remove energy from the system. Variable stiffness hinges are effective in low-tension applications, while combining hinges with elastic bars is required in the presence of high-tension loads.