Applications of Electro-Rheological Fluids for Constrained Layer Damping Treatment of Structures

Constrained layer damping (CLD) technique employs solid viscoelastic materials for controlling the vibration characteristics of structures. The effectiveness of the CLD treatment depends on the dynamic mechanical properties and geometrical dimensions of the viscoelastic and constraining layers. It also depends on the percentage coverage of the structure by the viscoelastic and constraining layers. Since the complex dynamic properties of electro-rheological (ER) fluids vary between those of viscoelastic liquids (at low levels of electric field strengths) and those of viscoelastic solids (at high levels of electric field strengths), ER fluids can be used in an adaptive form for CLD applications. The results of experimental and analytical studies on the vibration characteristics of a clamped-clamped plate which is partially and totally filled with an ER fluid are presented. The ER fluid employed is a mixture of 50 wt% of an analytical reagent grade of starch dissolved in 50 wt% of a silicone oil. It is shown that for the particular ER fluid utilised, the variations of the frequency response functions and the modal parameters of the composite plate are more strongly dependent on the location and size of the ER fluid CLD treatment than on the electric field strength.