Shape memory alloys for structural control

The design of large flexible space structures evolve around stringent structural requirements for dimensional stability, pointing accuracy and vibration attenuation. In addition to the use of feedback controls, these structures must have some sort of inherent passive damping to achieve the desired objectives. One potential method of providing passive damping is to use a coupling or static member made of shape memory alloys.; This thesis focuses on the use of shape memory alloys (SMA) for augmenting structural damping. Non-linear models of the stress-strain behaviour of shape memory alloys are developed and compared to experimental stress-strain curves. These curves are markedly different from linear material due to a pseudoelastic hysteresis. Experimental results of the dynamics of a cantilever beam constrained by shape memory alloy wires are presented and compared with simulations obtained using the non-linear models. A physical-based, input-output model is also posed to permit passive shape memory elements to be treated as feedback elements in the structure model. To validate and verify theoretical developments, a passive shape memory alloy device is developed and attached to a flexible structure experiment.; The experimental structure is used to investigate the application of shape memory alloy passive damping devices for vibration attenuation of flexible structures. Robust multivariable control techniques, specifically {dollar}mu{dollar}-synthesis. are used to design controllers to increase the vibration attenuation of the augmented structure. Experimental results and simulations are presented and demonstrate the effectiveness of SMA wires as an integrated approach to vibration attenuation for flexible structures. Potential applications of the combination of passive SMA devices and robust multivariable control design include: control of buildings and bridges due to excitation from earthquakes and wind, vibration attenuation and control of large flexible space structures, modern automotive suspension systems, and flutter suppression.