Breathing Vibrations of a Horizontal Circular Cylindrical Tank Shell, Partially Filled With Liquid

1995 ◽  
Vol 117 (2) ◽  
pp. 187-191 ◽  
Author(s):  
M. Amabili ◽  
G. Dalpiaz
Keyword(s):  
Dynamic Behavior ◽  
Theoretical Approach ◽  
Cylindrical Shells ◽  
Horizontal Axis ◽  
Experimental Results ◽  
Liquid Level ◽  
Mode Shapes ◽  
Cylindrical Tank ◽  
Qualitative Explanation ◽  
Good Agreement

A theoretical approach to study breathing vibrations of cylindrical shells with horizontal axis, partially filled with liquid, is delineated and the results of some modal tests conducted on an industrially-manufactured tank are presented and discussed. The good agreement between theoretical and experimental results is preliminarily verified in the case of both an empty and completely full shell, in order to confirm that it is possible to apply the theoretical approach to real structures. The modal properties of a partially-filled shell as a function of liquid level are then experimentally studied, the mode shapes are compared using the Modal Assurance Criterium and a qualitative explanation of the dynamic behavior is proposed.

Effect of the Wave Amplitude on the Dynamic Behavior of a Wave Journal Bearing

2008 ◽  
Author(s):  
Nicoleta M. Ene ◽  
Florin Dimofte ◽  
Fred B. Oswald
Keyword(s):  
Dynamic Behavior ◽  
Wave Amplitude ◽  
Journal Bearing ◽  
Experimental Results ◽  
Transient Method ◽  
Poincaré Maps ◽  
Poincare Maps ◽  
Bearing Clearance ◽  
Bearing Behavior ◽  
Good Agreement

The effect of the wave amplitude on the dynamic behavior of a three-wave journal bearing is analyzed. A transient method was used to predict the wave bearing behavior after Fractional Whirl Frequency (FFW) occurs. Dynamic trajectories, Poincare´ maps, and FFT analyses are used to study the dynamic behavior of the journal bearing. It was found that the threshold of stability is strongly influenced by the wave amplitude. However, even when FFW occurs, the journal maintains its trajectory inside the bearing clearance. The predicted data were found to be in good agreement with the experimental results obtained at the NASA GRC.

Novel RFID Conformal Tag Antennas for Liquid Level Detection Applications

2020 ◽  
Vol 35 (10) ◽  
pp. 1255-1263
Author(s):  
Bassant El Swiefy ◽  
Mohamed Ahmed ◽  
Hala El Sadek ◽  
Wagdy Anis
Keyword(s):  
Liquid Level ◽  
Flexible Substrates ◽  
Cylindrical Tank ◽  
Wide Bandwidth ◽  
Rfid Tag ◽  
Conformal Antenna ◽  
Vivaldi Antenna ◽  
Good Agreement ◽  
Liquid Level Detection ◽  
Cst Microwave Studio

Detection of liquid level in large tanks is presented in this paper. The liquid level is detected using a transmitter and RFID tag antennas as a receiver. The transmitter antenna is a Vivaldi with wide bandwidth from 0.5 GHz to 3 GHz. The Vivaldi antenna is fabricated on FR4 with 𝜀𝑟 = 4.3 and thickness of 0.8 mm. Two conformal RFID tag antennas are used as receiver antennas. The conformal antenna is placed on Rogers Ultram 3850 flexible substrates with 𝜀𝑟 = 2.9 and a thickness of 0.1016 mm. The conformal antenna is designed to set on a cylindrical tank made from PVC material. The first tag works at 0.9 GHz and the second tag works at 2.45 GHz. Water and Oil are used as liquids for testing. The antennas are simulated using CST microwave studio simulator Ver.14. The system is also fabricated and measured. Good agreement is achieved between simulated and measured results.

Longitudinal Impact of Cylindrical Shells With Discontinuous Cross-Sectional Area

1972 ◽  
Vol 39 (4) ◽  
pp. 1005-1010 ◽  
Author(s):  
R. W. Mortimer ◽  
J. L. Rose ◽  
A. Blum
Keyword(s):  
Cylindrical Shells ◽  
Cross Sectional Area ◽  
Experimental Results ◽  
Longitudinal Impact ◽  
Sectional Area ◽  
Governing Equations ◽  
Cross Sectional ◽  
Inertia Effects ◽  
Stress Ratios ◽  
Good Agreement

The reflections and transmissions of longitudinal strain pulses in cylindrical shells having cross-sectional area discontinuities are studied both analytically and experimentally. Three different theories were used to analyze this problem: the first, termed “bending” theory, includes the transverse shear, radial inertia, and rotary inertia effects; the second is based on a modified “membrane” theory; the last is derived from the “uniaxial” theory. Solutions were obtained by solving each of the three systems of governing equations by the method of characteristics. The longitudinal and circumferential incident, reflected, and transmitted strain pulses calculated from the bending and membrane theories are shown to be in good agreement with the experimental results, whereas the uniaxial comparisons are poor. In addition, the calculated reflected and transmitted stress ratios are in good agreement with the experimental results; the ratios obtained from the uniaxial theory are shown to be generally inadequate.

Mechanics of Punching Circular Holes in Materials for Data Handling

1966 ◽  
Vol 88 (4) ◽  
pp. 377-386
Author(s):  
C. A. Queener ◽  
T. C. Smith ◽  
H. E. Gilkey
Keyword(s):  
Theoretical Model ◽  
Total Energy ◽  
Theoretical Approach ◽  
Experimental Results ◽  
Operating Parameters ◽  
Theoretical Treatment ◽  
Data Handling ◽  
Circular Holes ◽  
Punch Displacement ◽  
Good Agreement

A theoretical model is developed in an effort to predict the effect of various design and operating parameters on the mechanics of punching circular holes in relatively ductile, nonmetallic materials which are commonly used in data-handling equipment. Solutions are obtained for the various punch geometries most frequently used. Experimental results for punching force versus punch displacement, maximum punching force, and total energy expended during punching are in good agreement with the theoretical solutions. Although this work is primarily concerned with circular holes, the theoretical approach used is equally applicable to the punching of other hole geometries, such as rectangular holes. The possibility of extending the theoretical treatment to metal punching is also discussed briefly.

Dynamic Analysis of a Flapper-Nozzle Valve

1991 ◽  
Vol 113 (1) ◽  
pp. 163-167 ◽  
Author(s):  
S. J. Lin ◽  
A. Akers
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Nonlinear Theory ◽  
Previous Analysis ◽  
Experimental Results ◽  
Piston Flow ◽  
Good Agreement

A previous analysis into the dynamic behavior of the flapper-nozzle component of the electrohydraulic servovalve was performed after linearization of the equations relating to control piston flow (Lin and Akers, 1989a). This paper reports results for first-stage gain and for dynamic behavior when linearization has not been performed. Good agreement has been achieved between results calculated from the nonlinear theory presented and experimental results.

An accurate model for free vibration of porous magneto-electro-thermo-elastic functionally graded cylindrical shells subjected to multi-field coupled loadings

2021 ◽  
pp. 1045389X2098689
Author(s):  
Yiwen Ni ◽  
Shengbo Zhu ◽  
Jiabin Sun ◽  
Zhenzhen Tong ◽  
Zhenhuan Zhou ◽  
...  
Keyword(s):  
Free Vibration ◽  
Cylindrical Shells ◽  
Functionally Graded ◽  
Mode Shapes ◽  
Comparison Study ◽  
Accurate Model ◽  
Various Boundary Conditions ◽  
Proposed Model ◽  
Good Agreement ◽  
Analytical Frequency

An accurate model for vibration of a porous magneto-electro-thermo-elastic functionally graded (METE-FG) cylindrical shell made of barium titanate (BaTiO3) and cobalt diiron tetraoxide (CoFe2O4) with magneto-electro-thermal loadings is proposed within the framework of Hamiltonian system. Four types of porosity distribution profiles in the thickness direction are considered. By introducing a new total eigenvector, the higher-order governing differential equations are transformed into a set of lower-order equations. The exact solution for free vibration of METE-FG shells can be expanded in terms of specific symplectic eigenfunctions having seven possible explicit forms. Subsequently, analytical frequency equations and vibration mode shapes for METE-FG shells with various boundary conditions are derived simultaneously. A comparison study is presented to demonstrate the accuracy of the proposed model and very good agreement is observed. The effects of material properties and magneto-electro-thermal loadings on free vibration characteristics of METE-FG cylindrical shells are analyzed and discussed in detail.

Tire Vibrations

1977 ◽  
Vol 5 (4) ◽  
pp. 202-225 ◽  
Author(s):  
G. R. Potts ◽  
C. A. Bell ◽  
L. T. Charek ◽  
T. K. Roy
Keyword(s):  
Natural Frequencies ◽  
Standing Waves ◽  
Resonant Mode ◽  
Mode Shapes ◽  
Resonant Vibrations ◽  
Resonant Frequencies ◽  
Radial Tire ◽  
Analysis Techniques ◽  
Thin Ring ◽  
Good Agreement

Abstract Natural frequencies and vibrating motions are determined in terms of the material and geometric properties of a radial tire modeled as a thin ring on an elastic foundation. Experimental checks of resonant frequencies show good agreement. Forced vibration solutions obtained are shown to consist of a superposition of resonant vibrations, each rotating around the tire at a rate depending on the mode number and the tire rotational speed. Theoretical rolling speeds that are upper bounds at which standing waves occur are determined and checked experimentally. Digital Fourier transform, transfer function, and modal analysis techniques used to determine the resonant mode shapes of a radial tire reveal that antiresonances are the primary transmitters of vibration to the tire axle.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

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