Er Damper Damping Applications

Electro-rheological(ER) fluid is a kind of smart material. Because of its two attractive characteristics: controllability of its apparent viscosity and quick response (in several microseconds) to externally applied electric field, ER fluid can be applied to mechanical vibration control, used as controllable damping medium, mainly in the form of controllable dampers.In this thesis, a series of ER fluids which consist of starch and transformer oil were developed, their mechanical properties such as shear strength, shear module, etc. were measured using a homemade ER fluid static shear stress measuring meter. The influence of some factors, including ingredients of ER fluid, conductivity, intensity of applied electric field and environmental temperature etc., were discussed. During the investigation, an ER fluid, IAS-5, was developed and it has a static yield stress of 2.4Kpa at 3KV/mm, which is quite suitable for experimental research purpose.Upon analyzing the existing ER dampers, it is found that the operation mode of ER dampers can be classified into three categories: flow mode, shear mode and squeeze mode. In the present work, three shear mode multi-electrode ER dampers were designed and manufactured. For the standing-type ER damper, its damping properties were tested on LNSTRON8871 test machine, the force-displacement hysteresis cycles at different conditions were tested. Based on these experimental data, a mechanical model was proposed to describe the dynamic behavior of the damper and the parameters of the model were identified by an optimization method. Simulation results show that this model can represent the dynamic property of the damper quite well.Vibration control is regarded as the most promising application of ER fluid. In this work, the designed ER dampers were applied to control two type of structural vibrations: aircraft control surface flutter and truss vibration. In the flutter suppression test, two ER dampers were used to supply controllable damping to bending and torsion degree of freedoms of the control surface model, and wind tunnel flutter test show that the flutter speed of the model can be increased by 15%. The vibration suppression experiments of a two-floor truss were performed using one multi-electrode ER damper and the results show the feasibility of using ER damper to suppress vibration of truss structures.