Vibration and damping studies on a hollow sandwich box column with a viscoelastic/electrorheological/magnetorheological fluid core layer by the finite element method
01 Dec 2008-International Journal of Structural Stability and Dynamics (World Scientific Publishing Company)-Vol. 08, Iss: 04, pp 531-546
TL;DR: In this paper, the vibration and damping of a hollow sandwich box column containing a viscoelastic layer (VEL) or an electrorheological (ER) or magnetorheological fluid core with a constraining layer are analyzed and a comparison of performance is made.
Abstract: In this paper, the vibration and damping of a hollow sandwich box column containing a viscoelastic layer (VEL) or an electrorheological (ER) or magnetorheological (MR) fluid core with a constraining layer are analyzed and a comparison of performance is made. The hollow sandwich box column comprises two skin plates and a VEL/ER/MR fluid core layer. The finite element method is used to study the vibration and damping behaviors of the column. The natural frequencies and modal loss factors are obtained by solving the complex eigenvalue problem. The modal dampings and natural frequencies of the column are calculated for various electric as well as magnetic fields and their performance is compared with that of the viscoelastic core layer for the clamped-free boundary condition. Effects of core thickness, electric voltage and magnetic field on the vibration behavior of the sandwich box column are investigated.
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TL;DR: In this article, a three-layered sandwich beam with an adaptive magneto-rheological fluid (MRF) core layer is investigated, and the authors derived the instability bounds based on the 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.
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TL;DR: In this paper, an active flutter suppression of a simply supported circular sandwich cylindrical shell with a tunable electrorheological fluid (ERF) core, under axial supersonic gas flow, is studied.
Abstract: In this paper, active flutter suppression of a simply supported circular sandwich cylindrical shell with a tunable electrorheological fluid (ERF) core, under axial supersonic gas flow, is studied. The structural analysis is based on the classical thin shell theory, the ERF core is modeled as a first-order Kelvin–Voigt material, and the Krumhaar's modified supersonic piston theory is utilized to model the aerodynamic loading. Hamilton's principle is used to formulate the dynamic equations of motion together with the relevant boundary conditions. The generalized Fourier expansions in the circumferential and axial directions in conjunction with the classical Galerkin method are employed to set up the governing equations in the state-space domain. The critical free stream static pressures at which unstable oscillations arise are calculated for selected applied electric field strengths and cylinder length ratios. The Runge–Kutta time integration algorithm is used to determine the open-loop aeroelastic response of the system in two basic loading configurations, namely, a concentrated impulse point load and a sonic boom line load. Subsequently, a sliding mode control (SMC) strategy is adopted to actively suppress the closed loop system dynamic response in supersonic flight condition. Simulation results demonstrate performance and effectiveness of the adopted ERF-based SMC scheme. Limiting cases are considered and good agreements with the data available in the literature are obtained.
17 citations
TL;DR: In this article, the authors investigated the active control of the supersonic flutter motion of an elastically supported rectangular sandwich plate, which has a tunable electrorheological (ER) fluid core and rests on a Winkler-Pasternak elastic foundation, subjected to an arbitrary flow of various yaw angles.
Abstract: This paper investigates the active control of the supersonic flutter motion of an elastically supported rectangular sandwich plate, which has a tunable electrorheological (ER) fluid core and rests on a Winkler–Pasternak elastic foundation, subjected to an arbitrary flow of various yaw angles. The classical thin plate theory is adopted. The ER fluid core is modeled as a first order Kelvin–Voigt material, and the quasi-steady first order supersonic piston theory is employed for the aerodynamic loading. The generalized Fourier expansions in conjunction with Galerkin method are employed to formulate the governing equations in the state-space domain. The critical dynamic pressures at which unstable panel oscillations occur are obtained for a square sandwich plate, with or without an interacting soft/stiff elastic foundation, for selected applied electric field strengths and flow yaw angles. The Runge–Kutta method is then used to calculate the open-loop aeroelastic response of the system in various basic loading configurations. Subsequently, a sliding mode control (SMC) synthesis is set up to actively suppress the closed loop system response in yawed supersonic flight conditions with imposed excitations. The results demonstrate the performance, effectiveness, and insensitivity with respect to the spillover of the proposed SMC-based control system.
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References
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TL;DR: In this article, an efficient method for finite element modeling of three-layer laminates containing a viscoelastic layer is described, and modal damping ratios are estimated from undamped normal mode results by means of the modal strain energy method.
Abstract: An efficient method is described for finite element modelling of three-layer laminates containing a viscoelastic layer. Modal damping ratios are estimated from undamped normal mode results by means of the modal strain energy method. Comparisons are given between results obtained by the MSE method implemented in NASTRAN, by various exact solutions for approximate governing differential equations, and by experiment. Results are in terms of frequencies, modal damping ratios, and mechanical admittances for simple beams, plates, and rings. Application of the finite element -- MSE method in design of integrally damped structures is discussed.
542 citations
TL;DR: In this paper, a detailed analysis of vibration control capabilities of adaptive structures based on magnetorheological and electrorheological (ER) materials is presented. And the relative performances of both MR and ER adaptive beams are discussed in detail and their advantages and disadvantages are listed.
Abstract: Magnetorheological (MR) and electrorheological (ER) materials show variations in their rheological properties when subjected to varying magnetic and electric fields, respectively. They have quick time response, in the order of milliseconds, and thus are potentially applicable to structures and devices when a tunable system response is required. When incorporated into an adaptive structural system, they can yield higher variations in the dynamic response of the structure. This study presents a detailed analysis of vibration control capabilities of adaptive structures based on MR and ER materials, and compares their vibration minimization rates, time responses and energy consumption rates. Homogeneous one-dimensional MR and ER adaptive beam configurations were considered. A structural dynamic modeling approach was discussed and vibration characteristics of MR and ER adaptive beams were predicted for different magnetic and electric field levels. In addition to the model predictions, actual MR and ER adaptive beams were fabricated and tested. Both studies illustrated the vibration minimization capabilities of the MR and ER adaptive beams at different rates and environmental conditions. The relative performances of both MR and ER adaptive beams were discussed in detail and their advantages and disadvantages were listed.
167 citations
TL;DR: In this paper, the authors investigated the vibration suppression capabilities of magnetorheological (MR) materials in adaptive structures by varying the externally applied magnetic field level over the MR layer, the stiffness and damping properties of the adaptive beam can be varied.
Abstract: This paper discusses the investigation of vibration suppression capabilities of magnetorheological (MR) materials in adaptive structures. Homogeneous three-layered adaptive beams with MR materials sandwiched between two elastic layers were considered. By varying the externally applied magnetic field level over the MR layer, the stiffness and damping properties of the adaptive beam can be varied. These variations in the damping and stiffness properties can be used to tune the vibration characteristics of the adaptive beams such as natural frequencies, vibration amplitudes, mode shapes and loss factors. In this study, theoretical investigation of the MR adaptive beams vibration behavior based on the energy approach is accomplished. Experiments were performed to observe the theoretically predicted vibration responses in real time. From both studies, vibration suppression capabilities of MR adaptive beams were observed in the forms of shifts in natural frequency values, variations in loss factors, and vibration amplitudes.
159 citations
TL;DR: In this paper, a dynamic model of the beam structure based on thin plate theory was developed to predict the structural vibration characteristics of the ER adaptive beam, which included natural frequencies, loss factors, and transverse vibration responses at any location on the beam surface.
Abstract: The semi-active vibration control capabilities of Electrorheological (ER) material based adaptive beams were investigated in this study. The adaptive nature of such ER beams was achieved by controlling the pre-yield rheology of the ER material in response to varying applied electric field levels. The cross-sectional configuration of the beams considered was based on sandwiching the ER material between elastic face plates. A dynamic model of the beam structure based on thin plate theory was developed. The resulting dynamic model was able to predict the structural vibration characteristics of the ER adaptive beam. The information determined included natural frequencies, loss factors, and transverse vibration responses at any location on the beam surface. These vibration characteristics were determined as functions of excitation frequency and applied electric field level. Also the beam model was developed for generalized boundary conditions. The boundary conditions considered in this study were: clamped-clamped, clamped-free, clamped-simply supported and simply supported. Variations in the natural frequencies, loss factors, and transverse vibration response of the adaptive structure were analyzed for the listed boundary conditions. Additionally, effects of variations of the damping layer thickness of the adaptive beam on the structural loss factor was studied. Results were compared for the boundary conditions studied, and considerable variations in beam vibration responses were observed. As a result, the semi-active control capabilities of ER material based adaptive beams were theoretically illustrated.
80 citations
TL;DR: Many finite element models have been proposed for the analysis of sandwich plates as mentioned in this paper, and these models can be classified into two broad streams: the assumed displacement approach and the assumed-stress hybrid approach.
71 citations