Dynamic Performance of a Novel Magnetorheological Pin Joint

Abstract

Magnetorheological fluid (MRF) has received significant attention lately and MRF based devices have been proposed for structural control applications in recent years. The unique characteristics of MR fluid lies in its abilities to reversibly, repeatedly and instantly change from a free flowing liquid to a semi-solid state when exposed to a magnetic field. The electric power required to drive the MR devices can be easily provided by a battery. Possessing such unique properties, MR fluid based devices, such as MR damper, have become promising candidates in the semi-active control for civil structure applications. However, most of the published research has focused on application of MR dampers instead of exploring other type of MR devices. In addition, MR based devices exhibit complex nonlinear hysteresis behaviour and thus making their modelling a challenging task. In this paper, a novel MR fluid based device, namely MR pin joint, is proposed as a smart structural member in development of an intelligent civil structure that can suppress unwanted vibrations to ensure safety and serviceability of the structure. After design and fabrication, experiments have been conducted to characterise dynamic behaviours of the new device under different harmonic excitations with various input currents. Response time of the MR pin joint is compared when the MR pin joint is driven under different applied currents and moving speeds. Test data shows that the MR pin joint possesses a unique behaviour in the moment-angular velocity plot. A hyperbolic hysteresis model is proposed to model such unique behaviour. The investigation presented in the paper explores dynamic performance of MR pin joint. Finally, a parametric model is developed following the investigation on the correlation of coefficients in the proposed model with the loading conditions and applied currents.

A hysteresis model and parameter identification for MR pin joints using immune particle swarm optimization

“…The initial development of the smart device is to facilitate the real time control of civil structures [4]. The MRP can be used as a rotational connector at the column-beam connection in a structural frame.…”

“…Magnetorheological (MR) devices such as MR damper [1], [2], MR pin joint [3], [4], MR elastomer isolator [5], are recognized as smart devices for protection of engineering structures subject to external dynamic loadings such as seismic events, strong winds, destructive waves and vibration shocks. The application of visco-elastic MR fluid in civil or mechanical structures has received an increasing interest in comparison with other smart materials.…”

“…The research on mathematical modelling of MR pin joint (MRP) is relatively limited. A rotational hyperbolic hysteresis model of MRP was reported in [4] to be identified with a tangent hyperbolic function used for the evolutionary variable in the Bouc-Wen hysteresis. The model contains a torsional spring, a viscous dashpot and hyperbolic hysteretic element.…”

Future Intelligent Civil Structures: Challenges and Opportunities

“…With an electromagnetic coil to provide varying magnetic field, a smart pin-joint was capable of producing controllable moment resistance in a range of less than 1Nm to 30 Nm. Steady rotational testing [11][12] and dynamic cycling testing [13][14], shown in figure 4, were conducted using experimental setups shown in Figure 3. Theoretical evaluation [15] and hysteresis modelling [13][14] were carried out to characterise the performance of the MR pin-joint.…”

“…Steady rotational testing [11][12] and dynamic cycling testing [13][14], shown in figure 4, were conducted using experimental setups shown in Figure 3. Theoretical evaluation [15] and hysteresis modelling [13][14] were carried out to characterise the performance of the MR pin-joint. In the next stage work, the smart pin-joint will be installed in a two-story building model for applications on structural control and online system identification.…”