scholarly journals Free Vibration Characteristics of Rectangular Membranes Assuming Rounded-Edges Boundary

Vibration ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 265-270 ◽  
Author(s):  
Ouakad
Keyword(s):  
Wave Propagation ◽  
Free Vibration ◽  
Numerical Method ◽  
Higher Order ◽  
Differential Quadrature ◽  
Engineering Applications ◽  
Complex Mode ◽  
Discretization Methods ◽  
Higher Order Modes ◽  
Practical Engineering

This study examines the vibratory characteristics of rectangular membranes having an outer rounded-edges periphery. This class of membranes with rounded outer corners has a great advantage over membranes with a rectangular platform wave propagation at the boundary being greatly diffused. As a result, such membranes have a great potential for use in practical engineering applications, especially in waveguides-based structures. Based on an effective 2D Differential-Quadrature numerical method, the frequencies and respective modeshapes of a rectangular membrane with rounded-edges are computed. This method is shown to yield better versatility, efficiency and less computational execution than other discretization methods. The simulated results, showing complex mode exchanges occurring for the higher order modes, demonstrate advantageous use for such membrane patterns in the design of tunable waveguides.

Vibration Control of Hakucho Bridge Tower under Construction Using Actively-Controlled Mass Damper

1994 ◽  
Vol 6 (3) ◽  
pp. 262-265 ◽  
Author(s):  
Morito Takahashi ◽  
◽  
Satoshi Nishimoto ◽  
Koh Hashimoto ◽  
Yuji Koike ◽  
...  
Keyword(s):  
Free Vibration ◽  
Vibration Control ◽  
High Performance ◽  
Higher Order ◽  
Free Standing ◽  
Higher Order Modes ◽  
Mass Damper ◽  
Modes Of Vibration ◽  
Under Construction ◽  
Bridge Tower

Free-standing bridge towers, in general, suffer from vibrations caused by wind. In order to reduce vibrations, an actively-controlled mass damper was applied to Hakucho Bridge tower. In controlling vibrations, the node of the 2nd mode was selected as a settling point of sensors in order to maintain stability for higher order modes of vibration than that to be controlled. The damper was tested to verify damping performance by free vibration and measurement of vibrations caused by wind. High performance has been obtained from results of tests and the effectiveness of this method has been demonstrated.

scholarly journals Qualitative analysis of wave propagation in a 3-D magnetic flux tube

2007 ◽  
Vol 3 (S247) ◽  
pp. 355-359
Author(s):  
C. Jaimes ◽  
V. Fedun
Keyword(s):  
Wave Propagation ◽  
Magnetic Flux ◽  
Radial Velocity ◽  
Flux Tube ◽  
Phase Speed ◽  
Higher Order ◽  
Radial Dependence ◽  
Magnetic Flux Tube ◽  
Higher Order Modes ◽  
Kink Waves

AbstractIn this work wave propagation in a 3-D magnetic flux tube is solved numerically. The aim is to find interaction between kink waves and higher order modes (flute modes).A 60x60x60 cube is set up, containing a vertically oriented uniform magnetic flux tube, to solve numerically. Waves are observed propagating after triggering them with solution to the linearized system.The waves propagate acquiring a distinctive shape (seen in the crosscut of the tube at an arbitrary height showing the radial velocity maps). It is discarded that this is caused by the existence of higher order modes and is found that the radial dependence of the phase speed creates the motion.It was also found that the study of the profile of the radial velocity map of a slice of the system is a very intuitive way of analysing the modes of waves propagating through the flux tube.

A Higher Order Perturbational Approach in the Lubricated EHL Contacts With Non-Newtonian Lubricant

1992 ◽  
Vol 114 (1) ◽  
pp. 95-99 ◽  
Author(s):  
Jianming Wang ◽  
He Hao Zhang
Keyword(s):  
Newtonian Fluid ◽  
Higher Order ◽  
Line Contact ◽  
Order Method ◽  
Engineering Applications ◽  
Reynolds Equations ◽  
First Order ◽  
Practical Engineering ◽  
First Order Method

In previous papers [7–9], investigations have been made on the influence of several kinds of non-Newtonian lubricants on the line contact EHL by using a first-order perturbational method. The practical engineering applications have been also tried successfully through papers [10–14]. However, when the slide/roll ratio reduces to zero the derived Reynolds equations become either the exact equations for a Newtonian lubricant or totally invalid. This, of course, is not the case for a natural non-Newtonian fluid. The facts show the limitation of the first-order method and also implies that with a tendency of decreased slide/roll ratio the first-order perturbational approach may bring a larger error and cannot describe accurately the behavior of non-Newtonian lubricants in the lubricated region. To improve it, a higher-order perturbational procedure is proposed in this paper.

On wave propagation and free vibration of piezoelectric sandwich plates with perfect and porous functionally graded substrates

2022 ◽  
pp. 1045389X2110721
Author(s):  
Mahmoud Askari ◽  
Eugenio Brusa ◽  
Cristiana Delprete
Keyword(s):  
Wave Propagation ◽  
Free Vibration ◽  
Analytical Solutions ◽  
Order Theory ◽  
Higher Order ◽  
Functionally Graded ◽  
Numerical Results ◽  
Rectangular Plates ◽  
Fg Plates ◽  
Higher Order Theory

This paper aims to develop analytical solutions for wave propagation and free vibration of perfect and porous functionally graded (FG) plate structures integrated with piezoelectric layers. The effect of porosities, which occur in FG materials, is rarely reported in the literature of smart FG plates but included in the present modeling. The modified rule of mixture is therefore considered for variation of effective material properties within the FG substrate. Based on a four-variable higher-order theory, the electromechanical model of the system is established through the use of Hamilton’s principle, and Maxwell’s equation. This theory drops the need of any shear correction factor, and results in less governing equations compared to the conventional higher-order theories. Analytical solutions are applied to the obtained equations to extract the results for two investigations: (I) the plane wave propagation of infinite smart plates and (II) the free vibration of smart rectangular plates with different boundary conditions. After verifying the model, extensive numerical results are presented. Numerical results demonstrate that the wave characteristics of the system, including wave frequency and phase velocity along with the natural frequencies of its bounded counterpart, are highly influenced by the plate parameters such as power-law index, porosity, and piezoelectric characteristics.

Importance of Higher Order Modes and Refined Theories in Free Vibration Analysis of Composite Plates

2009 ◽  
Vol 77 (1) ◽  
Author(s):  
S. Brischetto ◽  
E. Carrera
Keyword(s):  
Free Vibration ◽  
Degrees Of Freedom ◽  
Shear Deformation Theory ◽  
Single Layer ◽  
Free Vibration Analysis ◽  
Composite Plates ◽  
Higher Order ◽  
Harmonic Forms ◽  
Closed Form Solutions ◽  
Higher Order Modes

This paper evaluates frequencies of higher-order modes in the free vibration response of simply-supported multilayered orthotropic composite plates. Closed-form solutions in harmonic forms are given for the governing equations related to classical and refined plate theories. Typical cross-ply (0 deg/90 deg) laminated panels (10 and 20 layers) are considered in the numerical investigation (these were suggested by European Aeronautic Defence and Space Company (EADS) in the framework of the “Composites and Adaptive Structures: Simulation, Experimentation and Modeling” (CASSEM) European Union (EU) project. The Carrera unified formulation has been employed to implement the considered theories: the classical lamination theory, the first-order shear deformation theory, the equivalent single layer model with fourth-order of expansion in the thickness direction z, and the layerwise model with linear order of expansion in z for each layer. Higher-order frequencies and the related harmonic modes are computed by varying the number of wavelengths (m,n) in the two-plate directions and the degrees of freedom in the plate theories. It can be concluded above all that—refined plate models lead to higher-order frequencies, which cannot be computed by simplified plate theories—frequencies related to high values of wavelengths, even the fundamental ones, can be wrongly predicted when using classical plate theories, even though thin plate geometries are analyzed.

scholarly journals Electrical characterisation of higher order spin wave modes in vortex-based magnetic tunnel junctions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Alex. S. Jenkins ◽  
Lara San Emeterio Alvarez ◽  
Samh Memshawy ◽  
Paolo Bortolotti ◽  
Vincent Cros ◽  
...  
Keyword(s):  
Spin Wave ◽  
Tunnel Junctions ◽  
Magnetic Tunnel Junctions ◽  
Higher Order ◽  
Spin Torque ◽  
Micromagnetic Simulations ◽  
Higher Order Modes ◽  
Spin Diode ◽  
Super High Frequency ◽  
Wave Modes

AbstractNiFe-based vortex spin-torque nano-oscillators (STNO) have been shown to be rich dynamic systems which can operate as efficient frequency generators and detectors, but with a limitation in frequency determined by the gyrotropic frequency, typically sub-GHz. In this report, we present a detailed analysis of the nature of the higher order spin wave modes which exist in the Super High Frequency range (3–30 GHz). This is achieved via micromagnetic simulations and electrical characterisation in magnetic tunnel junctions, both directly via the spin-diode effect and indirectly via the measurement of the coupling with the gyrotropic critical current. The excitation mechanism and spatial profile of the modes are shown to have a complex dependence on the vortex core position. Additionally, the inter-mode coupling between the fundamental gyrotropic mode and the higher order modes is shown to reduce or enhance the effective damping depending upon the sense of propagation of the confined spin wave.

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