Fundamentals of Vibrations
01 Dec 2013-Vol. 61, Iss: 12, pp 131-131
About: The article was published on 2013-12-01 and is currently open access. It has received 185 citations till now.
Citations
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TL;DR: In this paper, the authors combine piezoelectric shunt damping (PSD) and EMSD, and establish a unified governing equation of PSD and EMSD, and report the unique vibration control performance of these shunts.
Abstract: Smart materials and structures have attracted a significant amount of attention for their vibration control potential in engineering applications. Compared to the traditional active technique, shunt damping utilizes an external circuit across the terminals of smart structure based transducers to realize vibration control. Transducers can simultaneously serve as an actuator and a sensor. Such unique advantage offers a great potential for designing sensorless devices to be used in structural vibration control and reduction engineering. The present literature combines piezoelectric shunt damping (PSD) and electromagnetic shunt damping (EMSD), establishes a unified governing equation of PSD and EMSD, and reports the unique vibration control performance of these shunts. The schematic of shunt circuits is given and demonstrated, and some common control principles and equations of these shunts are summarized. Finally, challenges and perspective of the shunt damping technology are discussed, and suggestions made based on the knowledge and experience of the authors.
66 citations
TL;DR: In this paper, a force tracking control scheme for magnetorheological (MR) dampers is presented. But the authors focus on the nonlinearity of the MR damper force and use a control-oriented mapping approach to compensate for it.
Abstract: SUMMARY
This paper describes a novel force tracking control scheme for magnetorheological (MR) dampers. The feed forward, which is derived by a control-oriented mapping approach to reduce modelling effort of the inverse MR damper behaviour, compensates for the main steady-state nonlinearity of the MR damper force and thereby linearizes the plant. The resulting force tracking error due to model imperfections and parameter uncertainties is reduced by parallel proportional and integral feedback gains that are formulated based on the absolute values of actual MR damper force and desired control force due to the semi-active constraint of the MR damper force. The feedback is enriched by an anti-reset windup to account for MR damper current constraints and the concept of current reversal to accelerate demagnetization. The experimental validations of the force tracking control scheme on a rotational and a long-stroke MR damper demonstrate its robustness and efficacy. Copyright © 2015 John Wiley & Sons, Ltd.
57 citations
Cites methods from "Fundamentals of Vibrations"
...1002/stc is numerically computed from the energy of the measured actual force fa during one full period of length Td (20) and by the equivalent stiffness coefficient kequiv that is numerically computed from the potential energy of fa according to [44] which is stored from xa = 0 to xa =Xa and released from xa =Xa to xa = 0 by the damper (21)....
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TL;DR: In this paper, the authors describe the application of an on-line algebraic identification methodology for parameter and signal estimation in vibrating mechanical systems, which is used to estimate mass, stiffness, and viscous damping in simple mechanical systems using only position measurements.
Abstract: This paper describes the application of an on-line algebraic identification methodology for parameter and signal estimation in vibrating mechanical systems. An important property of the algebraic identification is that the parameter identification is not asymptotic but algebraic, that is, the parameters are computed as fast as the system dynamics are being excited by some external input or by changes in the initial conditions. The algebraic identification is then employed to estimate mass, stiffness, and viscous damping in simple mechanical systems using only position measurements. This approach is also used in the identification of frequency, phase, and amplitude of exogenous vibrations affecting a mechanical system. The algebraic identification is then combined with a certainty equivalence controller to asymptotically stabilize the system response and, simultaneously, cancel harmonic vibrations. The proposed adaptive-like control scheme is fast and robust against unknown parameters and frequency variations. Some numerical and experimental results illustrate the dynamic and robust performance of the algebraic identification and the active vibration controller.
42 citations
Cites background from "Fundamentals of Vibrations"
...Note that, the algebraic identification of wn would resemble an expression similar to the so-called Rayleigh’s quotient [14]....
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..., Rayleigh’s quotient, Stodola, Dunkerley, Rayleigh-Ritz) to get approximate values of fundamental/highest natural frequencies and mode shapes, however, they require a good knowledge of the mass and stiffness matrices [5,9,14]....
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TL;DR: The system design is motivated by the need for enabling technologies to replicate hovering flight and swimming in biological systems and using radio frequency magnetically coupled coils and in-house designed power electronics for low-frequency IPMC actuation.
Abstract: In this paper, we present the design of a wireless powering system for ionic polymer metal composites (IPMCs). The system design is motivated by the need for enabling technologies to replicate hovering flight and swimming in biological systems. IPMC wireless powering is achieved by using radio frequency magnetically coupled coils and in-house designed power electronics for low-frequency IPMC actuation. Parameters of the circuit components describing the resonantly coupled coils and the IPMC are experimentally identified. The power transfer from the external power source to the receiver at the IPMC is experimentally analyzed for a broad range of system parameters. Flow visualization and particle image velocimetry are used to ascertain the system capabilities. Moreover, the IPMC vibration in the wireless and wired configurations is compared.
40 citations
TL;DR: Unlike the previous ways to achieve the stop band, it is found that the zero rotational stiffness can provide a broad stop band at extremely low frequency, which starts from even almost zero frequency.
Abstract: Metamaterials realizing stop bands have attracted much attentions recently since they can break-through the well-known mass law. However, achieving the stop band at extremely low frequency has been still a big challenge in the fields of elastic metamaterials. In this paper, we propose a new metamaterial based on the idea of the zero rotational stiffness, to achieve extremely low frequency stop band for flexural elastic waves. Unlike the previous ways to achieve the stop band, we found that the zero rotational stiffness can provide a broad stop band at extremely low frequency, which starts from even almost zero frequency. To achieve the zero rotational stiffness, we propose a new elastic metamaterial consisting of blocks and links with the hinge connection. Analytic developments as well as numerical simulations evidence that this new metamaterial can exhibit extremely low and broad stop band, even at the quasi-static ranges. In addition, the metamaterial is shown to exhibit the negative group velocity at extremely low frequency ranges, as well as the quasi-static stop band, if it is properly designed.
39 citations
References
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TL;DR: In this paper, the authors combine piezoelectric shunt damping (PSD) and EMSD, and establish a unified governing equation of PSD and EMSD, and report the unique vibration control performance of these shunts.
Abstract: Smart materials and structures have attracted a significant amount of attention for their vibration control potential in engineering applications. Compared to the traditional active technique, shunt damping utilizes an external circuit across the terminals of smart structure based transducers to realize vibration control. Transducers can simultaneously serve as an actuator and a sensor. Such unique advantage offers a great potential for designing sensorless devices to be used in structural vibration control and reduction engineering. The present literature combines piezoelectric shunt damping (PSD) and electromagnetic shunt damping (EMSD), establishes a unified governing equation of PSD and EMSD, and reports the unique vibration control performance of these shunts. The schematic of shunt circuits is given and demonstrated, and some common control principles and equations of these shunts are summarized. Finally, challenges and perspective of the shunt damping technology are discussed, and suggestions made based on the knowledge and experience of the authors.
66 citations
TL;DR: The system design is motivated by the need for enabling technologies to replicate hovering flight and swimming in biological systems and using radio frequency magnetically coupled coils and in-house designed power electronics for low-frequency IPMC actuation.
Abstract: In this paper, we present the design of a wireless powering system for ionic polymer metal composites (IPMCs). The system design is motivated by the need for enabling technologies to replicate hovering flight and swimming in biological systems. IPMC wireless powering is achieved by using radio frequency magnetically coupled coils and in-house designed power electronics for low-frequency IPMC actuation. Parameters of the circuit components describing the resonantly coupled coils and the IPMC are experimentally identified. The power transfer from the external power source to the receiver at the IPMC is experimentally analyzed for a broad range of system parameters. Flow visualization and particle image velocimetry are used to ascertain the system capabilities. Moreover, the IPMC vibration in the wireless and wired configurations is compared.
40 citations
TL;DR: Unlike the previous ways to achieve the stop band, it is found that the zero rotational stiffness can provide a broad stop band at extremely low frequency, which starts from even almost zero frequency.
Abstract: Metamaterials realizing stop bands have attracted much attentions recently since they can break-through the well-known mass law. However, achieving the stop band at extremely low frequency has been still a big challenge in the fields of elastic metamaterials. In this paper, we propose a new metamaterial based on the idea of the zero rotational stiffness, to achieve extremely low frequency stop band for flexural elastic waves. Unlike the previous ways to achieve the stop band, we found that the zero rotational stiffness can provide a broad stop band at extremely low frequency, which starts from even almost zero frequency. To achieve the zero rotational stiffness, we propose a new elastic metamaterial consisting of blocks and links with the hinge connection. Analytic developments as well as numerical simulations evidence that this new metamaterial can exhibit extremely low and broad stop band, even at the quasi-static ranges. In addition, the metamaterial is shown to exhibit the negative group velocity at extremely low frequency ranges, as well as the quasi-static stop band, if it is properly designed.
39 citations
TL;DR: In this paper, an analytical solution for nonlinear vibra tion behavior of Euler-Bernoulli beams subjected to axial loads is provided. And the effect of vibration amplitude on the nonlinear frequency is discussed.
Abstract: The current research deals with application of a new analytical technique called Energy Balance Method (EBM) for a nonlinear problem. Energy Balance Method is used to obtain the analytical solution for nonlinear vibra tion behavior of Euler-Bernoulli beams subjected to axial loads. Analytical expressions for geometrically nonlinear vibration of beams are provided. The effect of vibration amplitude on the nonlinear frequency is discussed. Com parison between Energy Balance Method results and those available in literature demonstrates the accuracy of this method. In Energy Balance Method contrary to the con ventional methods, only one iteration leads to high accu racy of the solutions which are valid for a wide range of vibration amplitudes. http://dx.doi.org/10.5755/j01.mech.17.2.335
38 citations
TL;DR: Flexural vibrations of two thin beams that are coupled through an otherwise quiescent viscous fluid are studied and a boundary integral formulation is proposed to compute pertinent hydrodynamic functions to study the fluid effect.
Abstract: In this paper, we study flexural vibrations of two thin beams that are coupled through an otherwise quiescent viscous fluid. While most of the research has focused on isolated beams immersed in placid fluids, inertial and viscous hydrodynamic coupling is ubiquitous across a multitude of engineering and natural systems comprising arrays of flexible structures. In these cases, the distributed hydrodynamic loading experienced by each oscillating structure is not only related to its absolute motion but is also influenced by its relative motion with respect to the neighbouring structures. Here, we focus on linear vibrations of two identical beams for low Knudsen, Keulegan–Carpenter and squeeze numbers. Thus, we describe the fluid flow using unsteady Stokes hydrodynamics and we propose a boundary integral formulation to compute pertinent hydrodynamic functions to study the fluid effect. We validate the proposed theoretical approach through experiments on centimetre-size compliant cantilevers that are subjected to underwater base-excitation. We consider different geometric arrangements, beam interdistances and excitation frequencies to ascertain the model accuracy in terms of the relevant non-dimensional parameters.
37 citations