Magnetorheological Fluid Sandwich Research Articles

Dynamic instability, free vibration, and buckling analysis of MR fluid sandwich plates with FG face layers using the HSDT-based finite strip method

In the present study, by using a higher-order shear deformation plate theory (HSDT) and considering the second model proposed by Frostig and Thomsen, Dynamic instability, static buckling, and free vibration of the Magneto-Rheological (MR) fluid sandwich plates subjected to an axial periodic force is investigated. MR fluids are a group of smart materials whose rheological properties change rapidly with the application of a magnetic field. The upper and lower layers of the core (face layers) are selected from two different types. In the first group, they are made of functionally graded materials (FGMs), and the second group, consists of a matrix phase reinforced with carbon nanotubes (CNTs). The mechanical properties of the nanocomposite are considered in accordance with the extended rule of mixtures. The governing equations are derived using Hamilton’s principle and discretized by the finite strip method. The results obtained from the finite strip method are compared with the results of available literature. The impact of various parameters such as magnetic field intensity, core thickness, static and dynamic load factors, different boundary conditions, and the CNT distribution on the critical static buckling, natural frequency, and instability zone of the structure are investigated. The results show that increasing the MR fluid thickness has a stabilizing effect on the dynamic instability of the MR fluid sandwich plates.

Dynamic behavior of sandwich beams with different compositions of magnetorheological fluid core

ABSTRACT Magnetorheological fluid (MRF) sandwich beams belong to a class of adaptive beams that consists of MRF sandwiched between two or more face layers and have a great prospective for use in semi-active control of beam vibrations due to their superior vibration suppression capabilities. The composition of MRF has a strong influence on the MRF properties and hence affects the vibration characteristics of the beam. In this work, six MRF samples (MRFs) composed of combination of two particle sizes and three weight fractions of carbonyl iron powder (CIP) were prepared and their viscoelastic properties were measured. The MRFs were used to fabricate different MRF core sandwich beams. Additionally, a sandwich beam with commercially available MRF 132DG fluid as core was fabricated. The modal parameters of the cantilever MRF sandwich beams were determined at different magnetic fields. Further, sinusoidal sweep excitation tests were performed on these beams at different magnetic fields to investigate their vibration suppression behavior. MRF having larger particle size and higher weight fraction of CIP resulted in higher damping ratio and vibration suppression. Finally, optimal particle size and weight fraction of CIP were determined based on the maximization of damping ratio and minimization of weight of MRF.

A new reformulation of vibration suppression equations of functionally graded magnetorheological fluid sandwich beam

• Vibration suppression analysis of a FGMRF sandwich beam is analyzed. • A new decoupling approach is employed to exactly solve the problem. • Complex shear modulus of the MRF depend only severely upon the magnetic field. • Effects of various parameters on the modal parameters are considered. This article presented a new reformulation of governing equations of functionally graded magnetorheological fluid (FGMRF) sandwich beams using new auxiliary functions. This technique led to the decoupled vibration equations of the FGMRF sandwich beams and also to the analytical solutions for the in-plane and out of plane displacement fields by considering the Euler-Bernoulli beam theory (EBBT). The material properties of top and bottom layers were changed through the layer thickness according to a power-law distribution of the volume fraction of the constituents. Complex shear modulus of the magnetorheological fluid was varied continuously as a quadratic function of magnetic field intensity. Natural frequencies and corresponding loss factors were calculated with high accuracy in comparison with those available in literature. The effects of boundary conditions, geometric and material properties and the magnetic field intensity on vibrational modes were investigated. Results revealed that unlike the natural frequencies, the loss factors were more affected by the magnetic field.

Exact solution for shear deformable model of free damped vibration of magnetorheological fluid sandwich beam

An exact procedure is proposed to analyze vibration suppression of magnetorheological fluid (MRF) sandwich beams based on the Timoshenko shear deformable beam model. The equations of motion and corresponding boundary conditions are extracted using Hamilton’s principle. Then, by introducing four innovative functions, five highly coupled equations of motion are divided into three coupled equations and two independent equations. Employing a systematic procedure, the displacement fields and consequently frequency characteristic equation of the beam are exactly derived. High accuracy and stability of the exact natural frequencies and corresponding loss factors are shown in comparison with those available in literature.

Effects of carbon nanotube reinforcements on vibration suppression of magnetorheological fluid sandwich beam

Vibration suppression of a carbon nanotube–reinforced sandwich beam with magnetorheological fluid core is numerically investigated by employing the differential quadrature method. The beam has functionally graded carbon nanotube–reinforced composite base and constraining layers while its core layer is made of magnetorheological fluid. Four different types of distribution of carbon nanotubes along the thickness direction are considered. The extended rule of mixture is used to explain the effective material properties of the base and constraining layers of the beam. The equations of motion and corresponding boundary conditions are derived by applying Hamilton’s principle, and then these coupled differential equations are transformed into a set of algebraic equation applying the differential quadrature method. Natural frequencies and loss factors are extracted and compared with those available in literature. Convergence study has been performed to verify stability of the method. Effects of various parameters such as magnetic field intensity, mode number, and thickness of the magnetorheological fluid core layer on the natural frequencies and loss factors are studied.

Optimal locations of magnetorheological fluid pockets embedded in an elastically supported honeycomb sandwich beams for supersonic flutter suppression

In this paper, the optimal locations of finite number of embedded magneto-rheological fluid (MRF) pockets are calculated by using Single Objective Genetic Algorithm (SOGA) to suppress the supersonic flutter of an elastically supported sandwich beam with regular honeycomb interlayer. The structural formulation is based on the classical beam theory along with the Winkler-Pasternak foundation model, the MRF is modeled as a first order Kelvin-Voigt material, and the quasi-steady first order supersonic piston theory is employed to define the aerodynamic loading. The aeroelastic time response of honeycomb sandwich beams with different number of embedded MRF pockets are measured with/without foundation and flow stream under impact load. The simulation shows that by using MRF pockets in optimized locations in honeycomb sandwich structure, not only both lightness of honeycombs and variability of structural damping of MRF are considered, but also the supersonic flutter can be postponed to higher dynamic pressure compared to entirely honeycomb or MRF sandwich beams. Finally, in order to achieve the optimum compromise between mass and the flutter suppression, the best number of MR pockets along with the optimum magnetic field values in honeycomb sandwich structure is presented.

Aeroelastic analysis of a sandwich panel with partially treated magneto-rheological fluid core

This study considers the aeroelastic instability of a partially treated magneto-rheological fluid sandwich panel in supersonic airflow. The linear first-order piston theory is used for modeling the aerodynamic pressure. Using classical Hamilton’s principle along with the finite element method, the equations of motion are derived. The critical value of the non-dimensional aerodynamic pressure is obtained by traditional p-method scheme. The validity of the finite element formulation is examined through comparison with those obtained from the assumed mode formulation and the available results in the literature. Various parametric studies including the effects of applied magnetic field, core and constraining layer thicknesses are examined for several configurations of the core at simply-supported and clamped–clamped boundary conditions. The results show that the critical non-dimensional aerodynamic pressure of the sandwich panel is influenced not only by the magnetic field strength, core and constraining layer thicknesses but also strongly by the configuration of the core.

Dynamic characterization and parametric instability analysis of rotating magnetorheological fluid composite sandwich plate subjected to periodic in-plane loading

In this present study, the dynamic characterization and instability analysis of a rotating composite magnetorheological fluid sandwich plate under periodic in-plane loading are investigated. The go...

Finite element analysis of smart wind turbine blades sandwiched with magnetorheological fluid

A brand-new smart wind turbine blade with magnetorheological fluid (MRF) sandwiched was proposed in the research. The three-dimension entity model of a 750 KW wind turbine blades was established through the use of UG software, and three kinds of MRF sandwich layouts were considered into the blade model, that is, at the blade tip, at the blade root and at the whole blade from the root till the tip. The MRF was simplified as Kelvin-Voigt model in order to implement the finite element analysis based on ANSYS software, so that the mode shapes of smart wind turbine blade were revealed under various conditions with three different layout forms of MRF sandwich wind turbine blades. Analysis results showed that the magnetic field would influence the mode shapes of the wind turbine blade with MRF sandwiched, especially the torsion vibration. When the MRF was inserted through the blade from the root till the tip, the blade would dramatically influence the torsion vibration, so that the torsion vibration, which originally would have happened at higher orders, would arise in advance. While the MRF was located at the root of wind turbine blade, the torsion vibration would be postponed to arise at the higher orders. Therefore, the MRF should be located at the blade root, instead of the middle and the tip of wind turbine blade. Smart sandwich wind turbine blade will provide a new way to the vibration control of wind turbine blade.

Semi-Active Vibration Control of Laminated Composite Sandwich Plate – An Experimental Study

Abstract In this study, the vibration analysis of fully and partially treated laminated composite Magnetorheological (MR) fluid sandwich plates has been investigated experimentally. The natural frequencies of fully and partially treated laminated composite MR fluid sandwich plates have been measured at various magnetic field intensities under two different boundary conditions. The variations of natural frequencies with applied magnetic field, boundary conditions and location of MR fluid pocket have been explored. Further, a comparison of natural frequencies of fully and partially treated MR fluid sandwich structure has been made at various magnetic field intensities.

Aeroelastic characteristics of magneto-rheological fluid sandwich beams in supersonic airflow

Supersonic aeroelastic instability of a three-layered sandwich beam of rectangular cross section with an adaptive magneto-rheological fluid (MRF) core layer is investigated. The panel is excited by an airflow along it’s longitudinal direction. The problem formulation is based on classical beam theory for the face layers, magnetic field dependent complex modulus approach for viscoelastic material model and the linear first-order piston theory for aerodynamic pressure. The classical Hamilton’s principle and the assumed mode method are used to set up the equations of motion. The validity of the derived formulation is confirmed through comparison with the available results in the literature. The effects of applied magnetic field, core layer thickness and constraining layer thickness on the critical aerodynamic pressure are studied. The onset of instability in terms of the critical value of the nondimensional aerodynamic pressure for the sandwich beam is calculated using the p-method scheme. Simply supported, clamped–clamped and clamped-free boundary conditions are considered. The results show that the magnetic field intensity and thickness ratios have significant effects on the instability bounds.

Optimal layout of a partially treated laminated composite magnetorheological fluid sandwich plate

In this study, the optimal location of the MR fluid segments in a partially treated laminated composite sandwich plate has been identified to maximize the natural frequencies and the loss factors. The finite element formulation is used to derive the governing differential equations of motion for a partially treated laminated composite sandwich plate embedded with MR fluid and rubber material as the core layer and laminated composite plate as the face layers. An optimization problem is formulated and solved by combining finite element analysis (FEA) and genetic algorithm (GA) to obtain the optimal locations to yield maximum natural frequency and loss factor corresponding to first five modes of flexural vibration of the sandwich plate with various combinations of weighting factors under various boundary conditions. The proposed methodology is validated by comparing the natural frequencies evaluated at optimal locations of MR fluid pockets identified through GA coupled with FEA and the experimental measurements. The converged results suggest that the optimal location of MR fluid pockets is strongly influenced not only by the boundary conditions and modes of vibrations but also by the objectives of maximization of natural frequency and loss factors either individually or combined. The optimal layout could be useful to apply the MR fluid pockets at critical components of large structure to realize more efficient and compact vibration control mechanism with variable damping.

Vibration analysis of a partially treated laminated composite magnetorheological fluid sandwich plate

In this study, the vibration responses of a partially treated laminated composite magnetorheological (MR) fluid sandwich plate have been investigated. The governing differential equations of motion for a partially treated laminated sandwich plate embedding MR fluid and rubber as the core layer and the laminated composite plate as the face layers are presented in finite element formulation. The validity of the developed finite element formulation is demonstrated by comparing the results in terms of natural frequencies derived from the present finite element formulation with the experimental measurements. Various configurations of a partially treated laminated composite MR fluid sandwich plate are considered to study the effect of location and size of the MR fluid segment under various boundary conditions. The effect of magnetic field on the variation of natural frequencies and loss factor of the partially treated laminated composite MR fluid sandwich plate are also analyzed for various configurations at different boundary conditions. The free vibration mode shapes of various configurations of a partially treated laminated composite MR fluid sandwich plate are also presented. The forced vibration responses of the various configuration of a partially treated laminated composite MR fluid sandwich plate are also analyzed under harmonic force excitations. This analysis suggests that the natural frequency, loss factor and transverse displacements of the partially treated laminated composite MR fluid sandwich plate are strongly influenced by the location and size of the MR fluid segment apart from the intensities of the applied magnetic field. The application of the partial treatment alters the deflection pattern of the sandwich plate, particularly the location of peak deflection, which shows that it can be applied to critical components of a large structure to realize a more efficient and compact vibration control mechanism with variable damping.

Dynamic characterization of a laminated composite magnetorheological fluid sandwich plate

This study investigates the dynamic properties of a laminated composite magnetorheological (MR) fluid sandwich plate. The governing differential equations of motion of a sandwich plate embedding a MR fluid layer as the core layer and laminated composite plates as the face layers are presented in a finite element formulation. The validity of the developed finite element formulation is demonstrated by comparing the results in terms of the natural frequencies derived from the present finite element formulation with those in the available literature. Various parametric studies are also performed to investigate the effect of a magnetic field on the variation of the natural frequencies and loss factors of the MR fluid composite sandwich plate under various boundary conditions. Furthermore, the effect of the thickness of the MR fluid layer and the ply orientation of the composite face layers on the variation of the natural frequencies and loss factors are studied. The free vibration mode shapes under various boundary conditions of a MR fluid laminated composite sandwich plate are also presented. The forced vibration response of a MR fluid composite plate is investigated to study the dynamic response of the sandwich plate under harmonic force excitations in various magnetic fields. The study suggests that the natural frequency increases with increasing magnetic field, irrespective of the boundary conditions. The reduction in peak deflection at each mode under a harmonic excitation force with variation of the applied magnetic field shows the effectiveness of the MR fluid layer in reducing the vibration amplitude of the composite sandwich plate.

Finite Element Vibration Analysis of a Magnetorheological Fluid Sandwich Beam

This study investigates the dynamic properties of a sandwich beam with magnetorheological (MR) fluid as a core material between the two layers of the continuous elastic structure. Timoshenko beam theory has been employed to derive the governing differential equation of motion in the finite element form for the transverse vibration response of MR fluid sandwich beam. The validation of the developed finite element formulation is demonstrated by comparing the results in terms of natural frequencies evaluated with those of available literature. Various parametric studies are also 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.

Finite Element Analysis of a Simply Supported MR Fluid Sandwich Beam Based on ANSYS

This paper presents a method to simulate the mechanical behavior of magnetorheological fluid (MRF) subjected to magnetic field in the pre-yield region in ANSYS. The main idea is to devide an MRF element into two coincident elements, one of them has density and viscosity without shear modulus while another has shear modulus without density and viscosity. Taking a simply supported MRF sandwich beam as an example, good results and reasonable conclusion are obtained by comparing the results with the theoretical analysis and experimental study of Ref.[1]. The validity of finite element analysis is also investigated in this paper. At present, there is no exactly appropriate element type in ANSYS to model MRF, this kind of method called coincident elements method (CEM) will provide a new way to model the structures with MRF or MR dampers in ANSYS, and it also has reference roles for the future development of related elements in ANSYS.