Mode Of Cylinder Research Articles

Random Vibration Spectrum Analysis Based on Finite Element Method of High-Pressure Cylindrical Cylinders

In order to solve the vibration problems of car high-pressure cylindrical cylinders, Plate and Shell Vibration Theory is used for the calculation and analysis of the vibration characteristics. The vibration frequencies and modes of such cylinders are obtained. At the same time, the corresponding results are gotten through ANSYS12.0 simulation calculation. The similarities and differences of the both vibration frequencies and the changes of the respective modes are compared and analyzed to support the farther safety performance analysis of such cylinders in the vibration environment.

Vibration Analysis of High-Pressure Cylindrical Cylinders

In order to solve the vibration problems of car high-pressure cylindrical cylinders, Plate and Shell Vibration Theory is used for the calculation and analysis of the vibration characteristics. The vibration frequencies and modes of such cylinders are obtained. At the same time, the corresponding results are gotten through ANSYS12.0 simulation calculation. The similarities and differences of the both vibration frequencies and the changes of the respective modes are compared and analyzed to support the farther safety performance analysis of such cylinders in the vibration environment.

Coupled vibrations in hollow cylindrical shells of arbitrary aspect ratio

Vibrations of hollow cylinders have been the subject of considerable interest for many years. Piezoelectric cylinders offer a convenient system to study the vibration mode shapes, resonance frequencies and their mode coupling do to the ability to strongly and symmetrically excite extensional circumferential and axial vibration modes as well as flexural bending axial modes. While the mode repulsion of coupled circumferential and axial modes is generally widely known, their interaction gives rise to tubular flexural resonances in cylinders of finite thickness. Junger et al. [JASA 26, 709–713 (1954)] appears to have been first to discredit the notion of a forbidden zone, a frequency band free of resonant modes, as being an artifact of treating thin cylinders in the membrane limit. Aronov [JASA 125(2), 803–818 (2009)] showed experimental and theoretical proof of the presence of resonant modes throughout the spectrum as a result of the extensional mode coupling induced symmetric tubular bending modes in cylinders and their relationships as a function of different piezoelectric polarizations. That analysis used the energy method and the Euler-Lagrange equations based on the coupling of assumed modes of vibration and the synthesis of results using equivalent electromechanical circuits. This paper aims to both summarize and generalize those results for the applicability of passive cylindrical shells.

Surface vibrational modes in disk-shaped resonators

The natural frequencies and distributions of displacement components for the surface vibrational modes in thin isotropic elastic disks are calculated. In particular, the research is focused on even solutions for low-lying resonant vibrations with large angular wave numbers. Several families of modes are found which are interpreted as modified surface modes of an infinitely long cylinder and Lamb modes of a plate. The results of calculation are compared with the results of the experimental measurements of vibrational modes generated by means of resonant excitation in duraluminum disk with radius of ≈90mm and thickness of 16mm in the frequency range of 130–200kHz. An excellent agreement between the calculated and measured frequencies is found. Measurements of the structure of the resonant peaks show splitting of some modes. About a half of the measured modes has splitting Δfsplit/fmode at the level of the order of 10−5. The Q-factors of all modes measured in vacuum lie in the interval (2…3)×105. This value is typical for duraluminum mechanical resonators in the ultrasonic frequency range.

Analysis and Design of Hydraulic System of a Hydraulically Actuated Quadruped Robot

Abstract.Quadruped not only possess excellent kinetic speed and stability but also can adapt to various complex terrains, with the result that hydraulically actuated quadruped bionic robots with high load and outstanding adaptability have become the research hotspot. Hydraulic system, which is regarded as the dynamic part of a hydraulic quadruped robot, has a direct effect on the kinetic capability of robots. Based on dog’s structure bionics, hydraulically actuated quadruped robot was designed. In accordance with distribution modes of hydraulic cylinders which drive robot’s kinetic joints, a hydraulic oil-line system of the robot was designed in this paper. Combining the maximum design kinetic velocity, trotting movement pattern within foot’s work space was planned. Velocity curve of each joint’s hydraulic cylinder was obtained through simulation analysis of dynamic analysis software. According to the structure of asymmetrical hydraulic cylinder, minimum flux which the oil hydraulic pump theoretically requires at the robot’s maximum kinetic speed was calculated. With practical experience, the oilsource parameter which could meet the demands of hydraulic quadruped robot were determined.

Undulator radiation inside a dielectric waveguide

We investigate the radiation emitted by a charged particle moving along a helical orbit around a dielectric cylinder immersed into a homogeneous medium. Formulae are presented for the radiation intensity at large distances from the cylinder and for the radiation energy flux through the cross section of the cylinder. Under the Cherenkov condition for dielectric permittivity of the cylinder and the velocity of the particle image on the cylinder surface, strong narrow peaks appear in the angular distribution of the radiation in the exterior medium. The radiated energy inside the cylinder is redistributed among the cylinder modes and, as a result, the corresponding spectrum differs significantly from the homogeneous medium or free-space results. It is shown that the presence of the cylinder can lead to the considerable increase of the radiation intensity.

Adjustable subwavelength localization in a hybrid plasmonic waveguide

The hybrid plasmonic waveguide consists of a high-permittivity dielectric nanofiber embedded in a low-permittivity dielectric near a metal surface. This architecture is considered as one of the most perspective candidates for long-range subwavelength guiding. We present qualitative analysis and numerical results which reveal advantages of the special waveguide design when dielectric constant of the cylinder is greater than the absolute value of the dielectric constant of the metal. In this case the arbitrary subwavelength mode size can be achieved by controlling the gap width. Our qualitative analysis is based on consideration of sandwich-like conductor-gap-dielectric system. The numerical solution is obtained by expansion of the hybrid plasmonic mode over single cylinder modes and the surface plasmon-polariton modes of the metal screen and matching the boundary conditions.

Study on Identification Model of Cylinder Liner-Piston Ring Using Vibration Analysis Based on Fuzzy C-means Clustering

Diesel engines have been widely used in various engineering applications. The performance of diesel engines is influenced greatly by the operation condition of the cylinder liner-piston ring. It is therefore crucial to investigate and assess the working condition of the cylinder liner-piston ring. Literature review indicated that there are few studies on this issue. Therefore, this study proposes a condition identification model for the cylinder liner-piston ring via fuzzy C-means clustering technique. The experiments of different surface treatment of cylinder and several typical fault modes were carried out using an internal combustion engine simulation tester. The fuselage vibration signals of the diesel engine were collected.The wavelet packet was then used to obtain the high frequency components of the vibration signal and extract its energy characteristics. The vibration identification model based on fuzzy C-means clustering has been established according to these characteristics. The analysis results show that the proposed model can identify the operating mode of cylinder liner-piston ring according to the vibration characteristics effectively.

Vibrational modes of GaN nanowires in the gigahertz range**This manuscript is a contribution of the National Institute of Standards and Technology and is not subject to copyright in the United States.

Brillouin-light-scattering measurements and finite-element modeling of vibrational spectra in the range of 5–40 GHz are presented for an array of monocrystalline GaN nanowires with hexagonal cross sections. Analysis of the spectra is substantially complicated by the presence of a distribution of nanowire diameters. The measurements and calculations reveal a variety of modes with simple flexural, higher-order flexural, approximately ‘plane-strain’, approximately longitudinal and torsional displacement patterns that are similar to the corresponding modes of isotropic cylinders. The largest peaks in the spectra with acoustic angular wavenumbers in the range of 4 to ∼15 μm−1 were determined to arise from modes with relatively large transverse displacements, consistent with inelastic light scattering arising predominantly from surface ripple. These dominant modes have finite frequencies in the limit of zero wavenumber, corresponding to transverse standing waves. At higher wavenumbers, the spectra provide evidence for increased scattering through elasto-optic coupling, especially with respect to the emergence of a peak from a mode analogous to the longitudinal guided modes of thin films.

Ultrasonic resonant modes of piezoelectric balloons under internal pressure

Properties of a piezoelectric polymeric angioplasty balloon that may decrease the problems of acute closure and restenosis are evaluated in this study. Polyvinylidene difluoride (PVDF), a piezoelectric and pyroelectric polymer, has sufficient strength to serve as a standard angioplasty balloon as well as functioning as an ultrasonic transmitter and/or receiver. These properties enable potential therapeutic applications using ultrasound such as plaque ablation and sonotherapy as well as vulnerable plaque diagnosis using thermography. This study investigates the resonant structure of the PVDF balloon catheter in the frequency range 5-100 kHz. Vibrations of the piezoelectric balloon are modeled using cylindrical shell theory and compared with the observed modal frequencies of PVDF cylinders with and without internal pressure. Modal frequencies are determined by measuring the near-field pressure response of the PVDF cylinders using a high frequency microphone. A rich nodal structure is observed between 5 and 100 kHz with peak relative amplitudes measured between 42 and 45 kHz. Higher order modes for cylinders with 9 μm and 28 μm wall thickness increase in frequency as the internal pressure is increased. Experimental measurements confirm theoretical models that predict both pressure-dependent and pressure-independent resonant frequencies. Frequencies of pressure-dependent modes are calculated within 2.2% of measured values at high pressure.

Experiments on the periodic oscillation of free containers driven by liquid sloshing

AbstractExperiments on the time-periodic liquid sloshing-induced sideways motion of containers are presented. The measurements are compared with finite-depth potential theory developed from standard normal mode representations for rectangular boxes, upright cylinders, wedges and cones of$9{0}^{\ensuremath{\circ} } $apex angles, and cylindrical annuli. It is assumed that the rectilinear horizontal motion of the containers is frictionless. The study focuses on measurements of the horizontal oscillations of these containers arising solely from the liquid waves excited within. While the wedge and cone exhibit only one mode of oscillation, the boxes, cylinders and annuli have an infinite number of modes. For the boxes, cylinders and one of the annuli, we have been able to excite motion and record data for both the first and second modes of oscillation. Frequencies$\omega $were acquired as the average of three experimental determinations for every filling of mass$m$in the dry containers of mass${m}_{0} $. Measurements of the dimensionless frequencies$\omega / {\omega }_{R} $over a range of dimensionless liquid masses$M= m/ {m}_{0} $are found to be in essential agreement with theoretical predictions. The frequencies${\omega }_{R} $used for normalization arise naturally in the mathematical analysis, different for each geometry considered. Free surface waveforms for a box, a cylinder, the wedge and the cone are compared at a fixed value of$M$.

Study of Circumferential Waves on a Poroelastic Cylinder

The dispersion relations of acoustic modes in poroelastic cylinders with and without elastic shell coating are determined and solved. The influence of elastic frame parameters and the Biot parameters on the dispersion curves is studied in the configuration with and without coating. The dispersive Rayleigh and whispering gallery waves are highly sensitive to the density and the shear modulus of the skeleton, opening a perspective for the evaluation of the mechanical parameters of poroelastic materials confined in cylindrical tubes during the manufacturing process. The predicted dispersion curves are validated with experimental results obtained by use of different experimental set-up in the case of a porous circular cylinder.

Mode properties and coupling conditions for scattering by circular cylinders: Comparison of liquid‐filled shells and solid cylinders.

Simple circular cylinders are sometimes used as proud test objects when developing and testing sonar systems in realistic environments [Williams et al., J. Acoust. Soc. Am. 127, 3356–3371 (2010)]. In endeavors of this type it remains important to have a good physical understanding of the coupling of sound to the modes of infinite and finite tilted and broadside circular cylinders. The present talk reviews some experimental and theoretical investigations of the free field scattering properties including some results of quantitative ray theory for scattering amplitudes. Plotting the frequency response as a function of the tilt angle of a cylinder reveals coupling loci normally associated with axial modes of the cylinder. In certain limiting cases the coupling loci for helical modes of solid metallic cylinders resemble the coupling loci for liquid‐filled shells having appropriate boundary conditions. It is also possible for internal modal properties of long liquid‐filled metallic shells to modulate the backscattering amplitude of meridional ray features. [Work supported by the ONR.]

Finite cylinder mode identification in scattering using finite elements, Fourier decomposition, and background subtraction.

Finite elements are widely used for calculating the acoustic scattering by objects for which a partial wave series solution is not available. When interpreting the results of such calculations for the purpose of developing signal processing methods, it can be helpful to identify the elastic modes of the object excited by the incident sound. One approach to this is examined here for a finite metallic circular cylinder. Since the object is rotationally symmetric it is convenient to use a Fourier basis to speed up the calculations [Zampolli et al., J. Acoust. Soc. Am. 122, 1472–1485 (2007)]. This also has the advantage of using the scattering amplitude associated with a given Fourier index to extract mode information. It is also helpful to subtract from the computed complex amplitude the corresponding scattering by a rigid or nearly rigid object having the same size and shape as the cylinder. For some situations this can be compared with quantitative ray theory and experimental results using reversible synthetic aperture sonar processing. [Work supported by ONR.]

The Hydraulic Jack-Up System Design on the Ocean Petroleum Platform 161 - the First Self-Installing Product Platforms in China

The paper introduces the hydraulic jack-up system design about the first domestic self-installing product platform. According to the production platform features, the jack-up system chooses the mode of hydraulic cylinder driving. So the jack-up system is both economy and safe reliability. The jack-up system is equipped with proportional valve and the PLC programmable controller which has a touch panel to show the inclination of the platform, the synchronism of hydraulic cylinders in the four legs of the platform, the state of the piston pin and the alarm indication of the hydraulic power station etc.

Buckling Modes and Developable Postbuckling Modes of Axially Compressed Short Circular Cylindrical Shells

The developability of thin circular cylindrical shells of infinite length leads to the postbuckling modes described by Yoshimura for shells under axial compression. Yamaki et al. calculated and measured experimentally the postbuckling modes of a cylindrical shell of finite length under axial compression. However, they did not calculate the buckling mode of the cylinder. To clarify the entire process of mode changes during buckling and postbuckling, an axial buckling mode is calculated and drawn for the cylinder whose corresponding postbuckling modes have been investigated by Yamaki et al. The axial postbuckling modes of finite length cylinders are shown to be deployable on flat surfaces due to the developability of cylindrical shells.

Study on the Acoustic Field Characters of a Flame Tube Model of An Annular Combustion Chamber

Combustion chamber is a core component of the hot section parts of aero engines, since it works under high-temperature and strong-noise circumstance for a long term, its lifespan is relative low and failure rate is relative high. The vibration generated by unstable combustion in the combustion chamber is very serious and the vibration generate noise, the vibration and noise will cause acoustic fatigue damage, thus affect the lifespan of the combustion chamber. According to the requirements of the integrated program on the design of aero engine structure, the structural fatigue prediction and lifespan analysis of combustion chamber are the critical issues in engine design, especially with the advent of new concepts like high efficiency and low pollution, design of new type combustion chamber is becoming more and more important. The present paper elaborated on the basic theory of cavity acoustic mode, analyzed the characteristics of acoustic field of flame tube model of an annular combustion chamber based on the FEM and BEM, and measured the open acoustic modes of dual wall cylinder modes with the experimental approach.

Multi-mode interactions in vortex-induced vibrations of flexible curved/straight structures with geometric nonlinearities

A general low-order fluid–structure interaction model capable of evaluating the multi-mode interactions in vortex-induced vibrations of flexible curved/straight structures is presented. Cross-flow motions due to unsteady lift forces of inclined sagged cables and tensioned beams in uniform currents are investigated. In contrast to a linear equation governing the transverse motion of straight beams or cables typically considered in the literature, coupled horizontal/vertical (axial/transverse) displacements and geometric nonlinearities of curved cable (straight beam) are accounted for. A distributed nonlinear wake oscillator is considered in the approximation of space–time varying hydrodynamics. This semi-empirical fluid force model in general depends on the mass-damping parameter and has further been modified to capture both the effects of varying initial curvatures of the inclined cylinder and the Reynolds number. Numerical simulations are performed in the case of varying flow velocities and parametric results highlight several meaningful aspects of vortex-induced vibrations of long flexible cylinders. These comprise multi-mode lock-in, sharing, switching and interaction features in the space and time domains, the estimated maximum modal and total amplitudes, the resonant nonlinear modes of flexible cylinders and their space–time modifications, and the influence of fluid/structure parameters. A shortcoming of single-mode or linear structural model is underlined. Some quantitative and qualitative comparisons of numerical/experimental results are discussed to demonstrate the validity and required improvement of the proposed modelling and analysis predictions.

Effects of the Source on Wave Propagation in Pile Integrity Testing

One-dimensional stress wave theory is widely used to analyze quantitatively the reflections in low-strain integrity testing of piles. However, a point or disk loading produces body and Rayleigh waves near the pile top. The multireflections of these waves from the lateral surface of a pile are present in the wave field near the pile top. Effects of three-dimensional waves on the near field responses are obvious. These effects can be interpreted erroneously by an inexperienced user as “noises” or “pile anomalies.” To investigate wave propagation in the longitudinal direction, the behavior of the waves in the far field (some distance below the pile top) is studied by theoretical analysis of the longitudinal modes in free cylinders and numerical simulations. The wave pattern at the pile top is analyzed based on the response of an elastic half-space to a harmonic disk loading. The results show that when the ratio of the characteristic length of an impact pulse to the cylinder radius is large enough, the components of Rayleigh waves in the wave field at the pile top are diminished; the waves in the far field behave approximately as plane waves; the responses at positions between 1/2R and 3/4R from the pile axis are less affected by the multireflections. The results from numerical simulations support the practical recommendation to use a ratio of characteristic wavelength to pile radius larger than four. Under this condition, the reflections from the far field (say deeper than two pile diameters) can be analyzed from the responses at receiver positions about 0.6R from the pile axis based on one-dimensional stress wave theory.

Actuating Mechanism and Design of a Cylindrical Traveling Wave Ultrasonic Motor Using Cantilever Type Composite Transducer

BackgroundUltrasonic motors (USM) are based on the concept of driving the rotor by a mechanical vibration excited on the stator via piezoelectric effect. USM exhibit merits such as simple structure, quick response, quiet operation, self-locking when power off, nonelectromagnetic radiation and higher position accuracy.Principal FindingsA cylindrical type traveling wave ultrasonic motor using cantilever type composite transducer was proposed in this paper. There are two cantilevers on the outside surface of cylinder, four longitudinal PZT ceramics are set between the cantilevers, and four bending PZT ceramics are set on each outside surface of cantilevers. Two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the cylinder are excited by the composite transducer. In this new design, a single transducer can excite a flexural traveling wave in the cylinder. Thus, elliptical motions are achieved on the teeth. The actuating mechanism of proposed motor was analyzed. The stator was designed with FEM. The two vibration modes of stator were degenerated. Transient analysis was developed to gain the vibration characteristic of stator, and results indicate the motion trajectories of nodes on the teeth are nearly ellipses.ConclusionsThe study results verify the feasibility of the proposed design. The wave excited in the cylinder isn't an ideal traveling wave, and the vibration amplitudes are inconsistent. The distortion of traveling wave is generated by the deformation of bending vibration mode of cylinder, which is caused by the coupling effect between the cylinder and transducer. Analysis results also prove that the objective motions of nodes on the teeth are three-dimensional vibrations. But, the vibration in axial direction is minute compared with the vibrations in circumferential and radial direction. The results of this paper can guide the development of this new type of motor.