Smart TLCD using synthetic hydrocarbon based MR fluid: An experimental study

A new smart semi-active device, called magneto-rheological - tuned liquid column damper (MR-TLCD) has recently been devised by the authors for wind-induced vibration control of tall building structures. The damping performance of this device can be continuously changed and is controllable by altering magnetic filed applied on the MR fluid at the bottom of a U-tube container. Numerical simulations have been conducted to demonstrate its effectiveness in both open-loop and closed-loop control modes, and MR - TLCD prototypes using different solvents in magneto-rheological fluid (MRF) have been manufactured in laboratory. This paper presents an experimental study of an MR-TLCD using one kind of synthetic hydrocarbon - poly-alpha-olefin (PAO) as solvent of MRF. The prototype is fabricated using a U-tube container with PAO-based MRF, of which the viscosity can be altered in milliseconds by exerting voltage to the electromagnetic coils at the bottom of the tube. It was tested on a hanging shaking table by positioning it on the top of a structural model which was subjected to ground excitation. Open-loop control tests were carried out with a spectrum of voltage inputs to the MR - TLCD under sweeping sine excitation. The tests show that the smart MR-TLCD can effectively mitigate structural vibration response and a maximum response reduction can be achieved when an optimal voltage input to the damper is exerted, validating the findings of theoretical and simulation studies.