Vibration Modes of Radial Tires: Measurement, Prediction, and Categorization Under Different Boundary and Operating Conditions

2005 ◽  
Author(s):  
Robert L. Wheeler ◽  
Hans R. Dorfi ◽  
Brian B. Keum
Keyword(s):  
Operating Conditions ◽  
Vibration Modes

Tire Vibration Modes and Effects on Vehicle Ride Quality

1993 ◽  
Vol 21 (1) ◽  
pp. 23-39 ◽  
Author(s):  
R. W. Scavuzzo ◽  
T. R. Richards ◽  
L. T. Charek
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Operating Conditions ◽  
Modal Testing ◽  
Ride Quality ◽  
Vibration Modes ◽  
Inflation Pressure ◽  
Passenger Cars ◽  
Element Modeling ◽  
Road Surfaces

Abstract Tire vibration modes are known to play a key role in vehicle ride, for applications ranging from passenger cars to earthmover equipment. Inputs to the tire such as discrete impacts (harshness), rough road surfaces, tire nonuniformities, and tread patterns can potentially excite tire vibration modes. Many parameters affect the frequency of tire vibration modes: tire size, tire construction, inflation pressure, and operating conditions such as speed, load, and temperature. This paper discusses the influence of these parameters on tire vibration modes and describes how these tire modes influence vehicle ride quality. Results from both finite element modeling and modal testing are discussed.

Design of Ultrasonic Vibrator for Conformal Coating Spray in LED Packaging

2009 ◽  
Vol 79-82 ◽  
pp. 715-718
Author(s):  
Byeong Ho Son ◽  
Seung Bok Choi ◽  
Quoc Hung Nguyen ◽  
Seung Min Hong ◽  
Soo Jin Lee ◽  
...  
Keyword(s):  
Longitudinal Vibration ◽  
Flow Characteristics ◽  
Film Surface ◽  
Wave Theory ◽  
Operating Conditions ◽  
Vibration Modes ◽  
Element Analysis ◽  
Surface Theory ◽  
Conformal Coating ◽  
Fluid Flow Characteristics

This paper presents the design of ultrasonic vibrator utilizing a piezoelectric actuator. After describing a geometric configuration of the proposed atomizer, an analytical model of the ultrasonic atomizer is formulated by considering liquid film surface theory and wave theory. The dynamic analysis is then undertaken using a finite element analysis to determine principal longitudinal vibration modes. An optimization is performed by taking the amplitude of the tip displacement as an objective function. The fluid flow characteristics of the proposed atomizer is also analyzed under operating conditions through commercial software FLUENT.

Evaluating Vibration Performance of a Subsea Pump Module by Full-Scale Testing and Numerical Modelling

2016 ◽  
Author(s):  
Pieter J. G. van Beek ◽  
Hajo P. Pereboom ◽  
Harmen J. Slot
Keyword(s):  
Evaluation Criteria ◽  
Full Scale ◽  
Operating Conditions ◽  
Piping System ◽  
Vibration Modes ◽  
Surrounding Water ◽  
Pipe System ◽  
Vibration Performance ◽  
Submerged Conditions ◽  
Pipe Vibration

Prior to subsea installation, a subsea system has to be tested to verify whether it performs in accordance with specifications and component specific performance evaluation criteria. It is important to verify that the assembled components work in accordance with the assumptions and design criteria used in the detailed engineering. These criteria also cover the vibration performance. In the current study, the pump module within the Åsgard subsea compression station has been subjected to such system evaluation test, including its vibration performance. Vibrations may be caused by internal and external flow through a complex process that is affected by numerous factors such as the piping geometry, flow and operating conditions and also the fluid properties. When severe, mechanical vibrations can lead to fatigue failure of the equipment components. One of the major parameters that affects the vibration response of the subsea piping is the surrounding water. It is generally known that surrounding water does participate in some vibration modes by adding mass to the total, dynamic mass participating in the vibration. Therefore, resonant frequencies of a piping system will have different values for non-submerged and submerged cases. In addition, the surrounding water can also lead to higher damping of the vibration modes. In this paper the effect of submerging a pipe system in water is quantified, by analyzing the changes in damping coefficient and the characteristics of measured pipe vibration in-situ. This is achieved by analysis of full-scale frequency response tests performed on a subsea pipe system within the pump module in both non-submerged and submerged conditions. The results are used for validation of numerical techniques that are used to quantify pipe vibration in submerged conditions. Different modeling techniques for the submerged case are investigated. It is shown that the effects from the surrounding water on pipe vibrations are different for small-bore piping than that for main piping. Furthermore the different modeling approaches and general observations and trends in damping coefficients are discussed and compared with the measurements.

scholarly journals Effect of Operating Conditions on Gearbox Noise

1992 ◽  
Author(s):  
Fred B. Oswald ◽  
James J. Zakrajsed ◽  
Dennis P. Townsend ◽  
William Atherton ◽  
Hsiang Hsi Lin
Keyword(s):  
Gear Tooth ◽  
Near Field ◽  
Operating Conditions ◽  
Sound Power ◽  
Vibration Modes ◽  
Spur Gears ◽  
Contact Ratio ◽  
Acoustic Intensity ◽  
Gear Noise ◽  
Constant Torque

Abstract Low-contact-ratio spur gears were tested in the NASA gear-noise rig to study the noise radiated from the top of the gearbox. The measured sound power from the gearbox top was obtained from a near-field acoustic intensity scan taken at 63 nodes just above the surface. The sound power was measured at a matrix of 45 operating speeds and torque levels. Results are presented in the form of a spectral speed map and as plots of sound power versus torque (at constant speed) and as sound power versus speed (at constant torque). Because of the presence of vibration modes, operating speed was found to have more impact on noise generation than torque level. A NASA gear dynamics code was used to compute the gear tooth dynamic overload at the same 45 operating conditions used for the experiment. Similar trends were found between the analytical results for dynamic tooth overload and experimental results for sound power. Dynamic analysis may be used to design high-quality gears with profile relief optimized for minimum dynamic load and noise.

scholarly journals Study of dynamics and rigidity of multifunctional coating of protective element of aircraft

2021 ◽  
Vol 5 (1) ◽  
pp. 86-94
Author(s):  
Keyword(s):  
Software Package ◽  
Operating Conditions ◽  
Vibration Modes ◽  
Structural Elements ◽  
Tabular Form ◽  
Space Technology ◽  
Structural Rigidity ◽  
Protective Element ◽  
Element Study ◽  
Protective Systems

In this work using a finite element study the author has numerically solved the problem of the dynamic behavior of a multifunctional coating of an aircraft protective element. The researcher conducted the simulation using the Femap with NX Nastran software package, The result of the modal analysis is the values and patterns of natural and secondary vibration modes of the multifunctional coating of the protective element of the aircraft using a special module the author has determined the distribution of effective modal masses in tabular form, Also, as a result of calculations, the author of the article obtained the value of the structural rigidity of the protective coating, The results presented in this work allow us to analyze the behavior of protective systems and structural elements of an aircraft with a multifunctional coating applied to the outer surface in real operating conditions, The design team can use the research results of this article in order to increase the efficiency of the development of a new structures and structures of a composite coating for multifunctional purposes, protective elements and materials for space technology

Asynchronous periodic contact modes for rotor vibration within an annular clearance

2003 ◽  
Vol 217 (10) ◽  
pp. 1101-1115 ◽  
Author(s):  
M O T Cole ◽  
P S Keogh
Keyword(s):  
Operating Conditions ◽  
Test Cases ◽  
Vibration Modes ◽  
Rotor Vibration ◽  
Contact Mode ◽  
System Parameters ◽  
Periodic Contact ◽  
Harmonic Decomposition ◽  
Mode Vibration ◽  
Annular Clearance

The dynamics of a multimode rotor-bearing system are analysed when the rotor contacts with a stator having annular clearance. By transforming to a rotating frame, all possible steady state rotor vibration modes that involve periodic contact with the surround may be predicted. Using a harmonic decomposition with generalized fundamental frequency, periodic solutions are obtained for rotor motions that involve asynchronous periodic contact. The analytical solutions are compared with previously published experimental results, which are predicted with considerable accuracy thus confirming the efficacy of the approach. Solutions are obtained for different test cases, which show how the amplitude and stability of the periodic contact modes are dependent on system parameters and operating conditions. In particular, for increased unbalance levels, the amplitude of the contact mode vibration is increased and the response of the rotor progresses from a bouncing forward whirl to a backward whirl-type motion. The nature of the identified rotor responses and implications for machine operation and reliability are discussed.

Cathodoluminescence of Catalyst Crystallites

1982 ◽  
Vol 40 ◽  
pp. 664-665
Author(s):  
E.D. Boyes ◽  
P.L. Gai ◽  
D.B. Darby ◽  
C. Warwick
Keyword(s):  
Defect Density ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Semiconductor Materials ◽  
Environmental Cell ◽  
High Resolution Structure ◽  
Commercially Important ◽  
Crystallographic Defects ◽  
Resolution Structure

The extended crystallographic defects introduced into some oxide catalysts under operating conditions may be a consequence and accommodation of the changes produced by the catalytic activity, rather than always being the origin of the reactivity. Operation without such defects has been established for the commercially important tellurium molybdate system. in addition it is clear that the point defect density and the electronic structure can both have a significant influence on the chemical properties and hence on the effectiveness (activity and selectivity) of the material as a catalyst. SEM/probe techniques more commonly applied to semiconductor materials, have been investigated to supplement the information obtained from in-situ environmental cell HVEM, ultra-high resolution structure imaging and more conventional AEM and EPMA chemical microanalysis.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

Slow-scan CCD cameras and low-dose High-Resolution Electron Microscopy: Direct and quantitative

1994 ◽  
Vol 52 ◽  
pp. 412-413
Author(s):  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Damage ◽  
Low Dose ◽  
Dynamic Range ◽  
High Resolution Electron Microscopy ◽  
Operating Conditions ◽  
Digital Data ◽  
Ccd Cameras ◽  
Resolution Electron

It has been known for many years that materials such as zeolites, polymers, and biological specimens have crystalline structures that are vulnerable to electron beam irradiation. This radiation damage severely restrains the use of high resolution electron microscopy (HREM). As a result, structural characterization of these materials using HREM techniques becomes difficult and challenging. The emergence of slow-scan CCD cameras in recent years has made it possible to record high resolution (∽2Å) structural images with low beam intensity before any apparent structural damage occurs. Among the many ideal properties of slow-scan CCD cameras, the low readout noise and digital recording allow for low-dose HREM to be carried out in an efficient and quantitative way. For example, the image quality (or resolution) can be readily evaluated on-line at the microscope and this information can then be used to optimize the operating conditions, thus ensuring that high quality images are recorded. Since slow-scan CCD cameras output (undistorted) digital data within the large dynamic range (103-104), they are ideal for quantitative electron diffraction and microscopy.

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

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