Frequency Analysis of Linearly Coupled Modes of MEMS Arrays

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Prashant N. Kambali ◽  
Gyanadutta Swain ◽  
Ashok Kumar Pandey
Keyword(s):  
Frequency Tuning ◽  
Approximate Model ◽  
Sensors And Actuators ◽  
Coupled Modes ◽  
Coupling Region ◽  
Reduced Order ◽  
Single Beam ◽  
Tuning Parameters ◽  
Out Of Plane ◽  
Fringing Field

Microelectromechanical system (MEMS) based arrays have been employed to increase the bandwidth and sensitivity of many sensors and actuators. In this paper, we present an approximate model to demonstrate the tuning of in-plane and out-of-plane frequencies of MEMS arrays consisting of fixed–fixed beams. Subsequently, we apply the Galerkin's method with single approximate mode to obtain the reduced-order static and dynamic equations. Corresponding to a given direct current (DC) voltage, we first solve the static equations and then obtain corresponding frequencies from the dynamic equation for single beam and arrays of multibeams. We compare the model with available experimental results. Later, we show the influence of different frequency tuning parameters such as the initial tensions, fringing field coefficients and the variable inter beam gaps between the microbeam and electrodes to control the coupling region and different modal frequencies of the beam. Finally, we obtain a compact model which can be used in optimizing the bandwidth and sensitivity of microbeams array.

Energy harvesting from aeroelastic vibrations induced by discrete gust loads

2016 ◽  
Vol 28 (1) ◽  
pp. 47-62 ◽  
Author(s):  
Claudia Bruni ◽  
James Gibert ◽  
Giacomo Frulla ◽  
Enrico Cestino ◽  
Pier Marzocca
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Flow Region ◽  
Rotational Displacement ◽  
Reduced Order ◽  
Piezoelectric Elements ◽  
Out Of Plane ◽  
Gust Loads ◽  
Three Degree Of Freedom ◽  
Euler Bernoulli Beam

This article evaluates the amount of energy that can be extracted from a gust using an aeroelastic energy harvester composed of a flexible wing with attached piezoelectric elements. The harvester operates in a subcritical flow region. It is modeled as a linear Euler–Bernoulli beam sandwiched between two piezoceramics. The extended Hamilton’s principle is used to derive the harvester’s equations of motion and an eigenfunction expansion is used to form a three-degree-of-freedom reduced-order model. The degrees of freedom retained in the model are two flexural degrees for the in-plane and out-of-plane displacements, and a torsional degree for the rotational displacement. Wagner and Küssner functions are used to represent the unsteady aerodynamic and gust loading, respectively. The amount of energy extracted from the system is then compared for two different deterministic gust profiles, 1-COSINE and two sharp-edged gusts forming a square gust, for various magnitudes and durations. The results show that the harvester is able to extract more energy from the square gust profile, although for both profiles the harvester extracts more power after the gust has subsided.

Insights into the displacement field in magnetoelectric composites

2019 ◽  
Vol 31 (3) ◽  
pp. 436-444 ◽  
Author(s):  
George Youssef ◽  
Scott Newacheck ◽  
Louay S Yousuf
Keyword(s):  
Computational Models ◽  
Excitation Frequency ◽  
Interface Condition ◽  
Composite Cylinder ◽  
Sensors And Actuators ◽  
Interferometric Technique ◽  
Magnetoelectric Composite ◽  
Out Of Plane ◽  
Finite Element Package ◽  
Plane Displacement

The performance of strain-mediated magnetoelectric composite multiferroics hinges on the interface condition in both direct and converse coupling paradigms. The objective of this article is to report experimentally validated computational models of composite cylinder structure consisting of an outer piezoelectric cylinder mechanically attached to an inner magnetostrictive layer. Three contact conditions were computationally investigated, including bonding, no separation, and standard definitions from the used finite element package. The simulations were used to extract the harmonic, modal, and transient responses of the composite cylinder structure, which were compared to experimental work. Under the influence of an AC electric field, the in-plane and out-of-plane displacement maps were simultaneously measured using a noncontact interferometric technique. Results from the harmonic analysis were used to tune the material properties and boundary conditions used in all subsequent simulations, whereas the resonance frequency was in excellent agreement with the experiment. The modal analysis was validated by comparing a subset of the experimental and computational vibrational modes. Finally, the transient analysis was found to be in reasonable agreement with the experimental results with a focus on the response at the excitation frequency. The validated analysis framework can be used in the development of sensors and actuators based on composite multiferroics cylinder structures.

Identification of Structural Systems With Limited Number of Sensors and Actuators

2004 ◽  
Author(s):  
Jun Yu ◽  
Maura Imbimbo ◽  
Raimondo Betti
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Solution Space ◽  
Order Model ◽  
Sensors And Actuators ◽  
Common Assumption ◽  
Reduced Order ◽  
Different Types ◽  
The Common ◽  
Inverse Vibration

The common assumption in the so-called linear inverse vibration problem, which provides the mass/stiffness/damping matrices of second order dynamic models, is the availability of a full set of sensors and actuators. In “reduced-order” problems (with limited number of instrumentation), only the components of the eigenvector matrix regarding the measured degrees of freedom can be successfully identified while nothing can be said about the components connected to the unmeasured degrees of freedom. This paper presents a recently developed “reduced-order” model and expands such a model to a “full-order” one that is quite useful in damage detection. The five representative categories of “reduced-order” problems, defined by considering different types of geometrical conditions, are analyzed and a discussion on their solution space has been performed. The effectiveness and robustness of this approach is shown by means of a numerical example.

How Reliable is the Pattern Adaptation Technique? A Modeling Study

2009 ◽  
Vol 102 (4) ◽  
pp. 2245-2252 ◽  
Author(s):  
Jay Hegdé
Keyword(s):  
Spatial Frequency ◽  
Frequency Tuning ◽  
Spatial Vision ◽  
Neural Mechanisms ◽  
System Level ◽  
Sinusoidal Grating ◽  
Tuning Parameters ◽  
Neuronal Ensemble ◽  
Spatial Frequency Tuning ◽  
Spatial Frequencies

Upon prolonged viewing of a sinusoidal grating, the visual system is selectively desensitized to the spatial frequency of the grating, while the sensitivity to other spatial frequencies remains largely unaffected. This technique, known as pattern adaptation, has been so central to the psychophysical study of the mechanisms of spatial vision that it is sometimes referred to as the “psychologist's microelectrode.” While this approach implicitly assumes that the adaptation behavior of the system is diagnostic of the corresponding underlying neural mechanisms, this assumption has never been explicitly tested. We tested this assumption using adaptation bandwidth, or the range of spatial frequencies affected by adaptation, as a representative measure of adaptation. We constructed an intentionally simple neuronal ensemble model of spatial frequency processing and examined the extent to which the adaptation bandwidth at the system level reflected the bandwidth at the neuronal level. We find that the adaptation bandwidth could vary widely even when all spatial frequency tuning parameters were held constant. Conversely, different spatial frequency tuning parameters were able to elicit similar adaptation bandwidths from the neuronal ensemble. Thus, the tuning properties of the underlying units did not reliably reflect the adaptation bandwidth at the system level, and vice versa. Furthermore, depending on the noisiness of adaptation at the neural level, the same neuronal ensemble was able to produce selective or nonselective adaptation at the system level, indicating that a lack of selective adaptation at the system level cannot be taken to mean a lack of tuned mechanisms at the neural level. Together, our results indicate that pattern adaptation cannot be used to reliably estimate the tuning properties of the underlying units, and imply, more generally, that pattern adaptation is not a reliable tool for studying the neural mechanisms of pattern analysis.

Frequency Tuning Characteristics of Multi-Layered Micro-Resonators Using Thermal and Piezoelectric Actuation

2006 ◽  
Vol 324-325 ◽  
pp. 647-650
Author(s):  
Il Kwon Oh ◽  
Dong Hyun Kim
Keyword(s):  
Thermal Loading ◽  
Frequency Tuning ◽  
Plane Deformation ◽  
Initial Imperfection ◽  
Piezoelectric Actuation ◽  
Natural Modes ◽  
Nonlinear Responses ◽  
Geometric Nonlinear ◽  
Out Of Plane ◽  
Selection Of

Frequency tuning characteristics of the multi-layered micro-resonators have been extensively investigated by using thermal and piezoelectric actuations. Based on the layerwise displacement theory and geometric nonlinear formulation, the nonlinear deformation and its attendant vibration characteristics of un-symmetrically deposited camped-camped micro-beams under piezoelectric and thermal actuations have been analyzed. The effects of the eccentric piezoelectric actuation and uniform thermal loading on the large deflection and natural modes were discussed with respect to geometric nonlinear responses and initial imperfection. Present results show that both piezoelectric and thermal actuations can effectively tune the resonant frequencies as increasing and decreasing desired values by the alternative selection of the dominance between in-plane deformation and out-of-plane deformation.

scholarly journals Reduced Order Model for Nonlinear Multi-Field-Coupled Spinning Shaft During Transient Operation Based on Coupled Modes Extracted by POD

2021 ◽  
Author(s):  
Mohammad A. Bani-Khaled ◽  
Ioannis Georgiou
Keyword(s):  
Natural Frequencies ◽  
Body Motion ◽  
Reduced Model ◽  
Order Model ◽  
Coupled Modes ◽  
Reduced Order ◽  
Operational Conditions ◽  
Proper Orthogonal ◽  
Deformation Modes ◽  
Spinning Shaft

Abstract Processing the numerical solution for the nonlinear spinning shaft using the Time- (Proper Orthogonal Decomposition) transform identifies the coupling between the rigid body motion and deformation as well as the coupling between the deformation modes. Laying on the fact that the POD characterizes the motion into set of optimum coupled modes, it is convenient to relay on them to derive nonlinear reduced order models. In this work, the discrete dynamics of nonlinear spinning shaft are processed using the POD method to produce optimum modes that are used to furnish bases to derive nonlinear coupled reduced model. The derived reduced model is tested at several operational conditions and compared to the full model characteristics. The reduced model produces back the dynamics; captures the natural frequencies and whirling.

Frequency Tuning Investigation of an Out-of-Plane Resonant Microstructure for a Capacitive Detection Magnetometer

2017 ◽  
pp. 65-100
Author(s):  
Petros Gkotsis ◽  
Mohamed Hadj Said ◽  
Farès Tounsi ◽  
Brahim Mezghani ◽  
Laurent A. Francis
Keyword(s):  
Frequency Tuning ◽  
Out Of Plane ◽  
Capacitive Detection
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