Vibration Control of Sandwich Beams Using Electro-Rheological Fluids

109

Magnetorheological (MR) materials exhibit rapid variations in their rheological properties when subjected to varying magnetic field and thus offer superior potential for applications in smart structures requiring high bandwidth. MR sandwich structures can apply distributed control force to yield variations in stiffness and damping properties of the structure in response to the intensity of the applied magnetic field and could thus provide vibration suppression over a broad range of external excitation frequencies. This study investigates the properties of a multi-layered beam with MR fluid as a sandwich layer between the two layers of the continuous elastic structure. The governing equations of a multi-layer MR beam are formulated in the finite element form and using the Ritz method. A free oscillation experiment is performed to estimate the relationship between the magnetic field and the complex shear modulus of the MR materials in the pre-yield regime. The validity of the finite element and Ritz formulations developed is examined by comparing the results from the two models with those from the experimental investigation. Various parametric studies have been performed in terms of variations of the natural frequencies and loss factor as functions of the applied magnetic field and thickness of the MR fluid layer for various boundary conditions. The forced vibration responses of the MR sandwich beam are also evaluated under harmonic force excitation. The results illustrate that the natural frequencies could be increased by increasing the magnetic field while the magnitudes of the peak deflections could be considerably decreased, which demonstrates the vibration suppression capability of the MR sandwich beam.

Section: Introductionmentioning

confidence: 99%

Vibration analysis of a multi-layer beam containing magnetorheological fluid

Rajamohan¹,

Rakheja²

2009

109

“…The damping characteristics of ER fluid-filled cantilevered beams in free oscillation were theoretically and/or experimentally investigated by several researchers [2][3][4][5][6]. Other investigations on ER sandwich structures include an ER-filled insert in a solid beam [7], an ER beam embedded with a fibre optic sensor [8] and cantilever ER beams rotating in the horizontal plane [9].…”

Section: Introductionmentioning

confidence: 99%

Vibration characteristics of MR cantilever sandwich beams: experimental study

Lara-Prieto¹,

Parkin²,

Jackson³

et al. 2009

Abstract.The concept of vibration controllability with smart fluids within flexible structures has been in the centre of interest in the past two decades. Although much research has been done on structures with embedded electrorheological (ER) fluids, there has been little investigation of magnetorheological (MR) fluid adaptive structures. In particular, a body of research on experimental work of cantilever MR beams is still lacking. This experimental study investigates controllability of vibration characteristics of magnetorheological cantilever sandwich beams. These adaptive structures are produced by embedding an MR fluid core between two elastic layers. The structural behaviour of the MR beams can be varied by applying an external magnetic field to activate the MR fluid. The stiffness and damping structural characteristics are controlled, demonstrating vibration suppression capabilities of MR fluids as structural elements. MR beams were fabricated with two different materials for comparison purposes. Diverse excitation methods were considered as well as a range of magnetic field intensities and configurations. Moreover, the cantilever MR beams were tested in horizontal and vertical configurations. The effects of partial and full activation of the MR beams were outlined based on the results obtained. Controllability of the beam's vibration response was observed in the form of variations in vibration amplitudes and shifts in magnitudes of the resonant natural frequency.

“…The impact of varying the stacking sequence of beams on the stiffness and the damping properties was studied. Phani and Venkatraman (2003) did an experimental investigation on the behavior of a sandwich beam with ER fluids acting as the core material. Significant improvements in the damping properties have been achieved in experiments and the damping contributions by viscous and non-viscous forces can be estimated by a force-state mapping (FSM) technique.…”

Section: Introductionmentioning

confidence: 99%

Vibration characteristics of electrorheological elastomer sandwich beams

Wei

Bai

Meng

et al. 2011

The vibration characteristics and control capabilities of a cantilever sandwich beam with electrorheological (ER) elastomers subjected to different electric fields are investigated in this study. Considering ER elastomers as viscoelastic damping materials with electrically controllable properties, a finite element model of a sandwich beam with an ER elastomer core is developed to predict the vibration responses of the proposed beam. An experimental analysis was also conducted to illustrate and evaluate the effects of an electric field on the frequency responses and natural frequencies of the sandwich beam. The results show that natural frequencies of the ER elastomer sandwich beam increase and vibration amplitudes at natural frequencies of the ER elastomer beam decrease, as the strength of the applied electric field increases. It is demonstrated that the vibration characteristics of ER elastomer beams are similar to those of ER fluid beams, which could be controlled by changing the strength of the applied electric field. This controllable characteristic of ER elastomer beams is useful for applications in engineering structures where variable performance is desired.