A multi-modal adaptive tuned mass damper based on shape memory alloys

This article deals with the design of an innovative adaptive multi-modal tuned mass damper able to change its eigenfrequencies to recover shifts of the natural frequencies of the primary system which needs to be damped. This is accomplished using systems of shape memory alloy wires connected to a number of masses equal to the number of modes to be damped. This article presents the analytical model used to describe the behaviour of the adaptive tuned mass damper, showing which parameters can affect the performances of the device. The layout proposed for the tuned mass damper proves to be able to act on a wide frequency range and to work adaptively on at least two eigenfrequencies at the same time with a given level of independence. The last goal is accomplished, thanks to the special features of the shape memory alloys, by heating (or cooling) each wire of the device independently and allowing the exploitation of two different effects: the change of the axial load in the wires and the change of the geometry of the device. The reliability of both the design approach and the model of the new device is proved by means of an experimental campaign performed considering a random disturbance.