Semi-active friction tendons for vibration control of space structures

• A new semi-active vibration control system has been proposed and numerically studied.
• The system uses cables to link semi-active friction dampers to the structure.
• The use of cables makes the system especially suitable for (large) space structures.
• Auxiliary springs, and a semi-active control law, prevent the cables from slackening.
• The system can work as semi-active or passive, being more effective as semi-active.

Semi-active vibration control systems are becoming popular because they offer both the reliability of passive systems and the versatility of active control without high power demands. In this work, a new semi-active control system is proposed and studied numerically. The system consists of variable-friction dampers linked to the structure through cables. Auxiliary soft springs in parallel with these friction dampers allow them to return to their initial pre-tensioned state. Using cables makes the system suitable for deployable, flexible and lightweight structures, such as space structures (spacecraft). A control system with three control laws applied to a single-degree-of-freedom structure is studied. Two of these laws are derived by using Lyapunov theory, whereas the third one is developed heuristically. In order to assess the performance of the control system, a parametric study is carried out through numerical simulations. An application of the proposed method to multi-degree-of-freedom structures is also presented and demonstrated through a numerical example. The system in semi-active mode is more effective than in passive mode and its effectiveness is less sensitive to loss of pre-tension.

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