Characterization of Transient Effects in Rotordynamic Vibrations Using Harmonic Wavelets

Volume 7A: 17th Biennial Conference on Mechanical Vibration and Noise ◽

10.1115/detc99/vib-8311 ◽

1999 ◽

Author(s):

Valeta Carol Chancey ◽

George T. Flowers

Keyword(s):

Steady State ◽

Journal Bearing ◽

Wavelet Coefficients ◽

Transient Effects ◽

State Behavior ◽

Absolute Value ◽

Harmonic Wavelets ◽

Oil Whirl ◽

Harmonic Wavelet

Abstract Traditional vibration analysis methods for rotating machinery consider steady state or near steady state behavior. Perhaps a key to identifying the source of some complex behaviors may be the transients associated with such phenomena. In an effort to develop a means of identifying transients, the application of harmonic wavelets is explored. Simple vibratory models were studied using harmonic wavelet analysis. Several general observations were made with characteristics found in the harmonic wavelet coefficients associated with particular behavior. Specifically, a relationship with transient growth and the absolute value of the harmonic wavelet coefficients was identified. Example experimental data was collected and analyzed from a bench top test rig with a journal bearing exhibiting oil whirl to illustrate the proposed methods.

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A Harmonic Wavelets Approach for Extracting Transient Patterns From Measured Rotor Vibration Data

Volume 4: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education; IGTI Scholar Award ◽

10.1115/2001-gt-0241 ◽

2001 ◽

Author(s):

Valeta Carol Chancey ◽

George T. Flowers ◽

Candice L. Howard

Keyword(s):

Vibration Analysis ◽

Transient Effects ◽

Rotor Vibration ◽

Harmonic Wavelets ◽

Vibration Data ◽

Harmonic Wavelet ◽

Vibration Signature ◽

The Fourier Transform ◽

Traditional Approaches

Vibration analysis is a powerful diagnostic tool for rotating machinery problems. Traditional approaches to vibration signature analysis have focused on the Fourier transform, which tends to average out transient effects. Recent work in the area of wavelets has allowed for the characterization of signals in frequency and in time, which, if properly interpreted, can provide substantial insight, particularly with regard to transient behaviors. There are many different wavelets, but the harmonic wavelet was developed specifically for vibration analysis. It uses an algorithm based upon the FFT, which makes it particularly attractive to many in the vibration analysis community. This paper considers the harmonic wavelet as a tool for extracting transient patterns from measured vibration data. A method for characterizing transient behaviors using the harmonic wavelet is described and illustrated using simulation and experimental results.

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A Harmonic Wavelets Approach for Extracting Transient Patterns From Measured Rotor Vibration Data

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.1520156 ◽

2002 ◽

Vol 125 (1) ◽

pp. 81-89 ◽

Cited By ~ 10

Author(s):

V. C. Chancey ◽

G. T. Flowers ◽

C. L. Howard

Keyword(s):

Fourier Transform ◽

Vibration Analysis ◽

Transient Effects ◽

Harmonic Wavelets ◽

Vibration Data ◽

Harmonic Wavelet ◽

Vibration Signature ◽

The Fourier Transform ◽

Traditional Approaches

Vibration analysis is a powerful diagnostic tool for rotating machinery problems. Traditional approaches to vibration signature analysis have focused on the Fourier transform, which tends to average out transient effects. Recent work in the area of wavelets has allowed for the characterization of signals in frequency and in time, which, if properly interpreted, can provide substantial insight, particularly with regard to transient behaviors. There are many different types of wavelets, but the harmonic wavelet was developed specifically for vibration analysis. It uses an algorithm based upon the fast Fourier transform (FFT), which makes it particularly attractive to many in the vibration analysis community. This paper considers the harmonic wavelet as a tool for extracting transient patterns from measured vibration data. A method for characterizing transient behaviors using the harmonic wavelet is described and illustrated with simulation and experimental results.

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Dynamic Characterization of Typical Electrical Circuits via Structural Properties

Mathematical Problems in Engineering ◽

10.1155/2016/7870462 ◽

2016 ◽

Vol 2016 ◽

pp. 1-13 ◽

Cited By ~ 8

Author(s):

Sofía Avila-Becerril ◽

Gerardo Espinosa-Pérez ◽

Paul Fernandez

Keyword(s):

Graph Theory ◽

Steady State ◽

Structural Properties ◽

Mesh Networks ◽

Dynamic Characterization ◽

State Behavior ◽

Electrical Circuits ◽

Mathematical Properties ◽

Steady State Behavior

The characterization of a class of electrical circuits is carried out in terms of both stability properties and steady-state behavior. The main contribution is the interpretation of the electrical topology (how the elements that conform the circuits are interconnected) in terms of mathematical properties derived from the structure of their models. In this sense, at what extent the topology by itself defines the dynamic behavior of the systems is explained. The study is based on the graph theory allowing capturing, departing from the well-known Kirchhoff laws, the topology of the circuits into several matrices with specific structure. The algebraic analysis of these matrices permits identifying conditions that determine whether the system is stable in the sense of Lyapunov and the kind of steady-state behavior that it exhibits. The approach is mainly focused on typical topologies widely used in practice, namely, radial, ring, and mesh networks.

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Steady-state behavior of finite compliant journal bearing using a piezoviscous polar fluid as lubricant

Mechanics & Industry ◽

10.1051/meca/2015040 ◽

2015 ◽

Vol 16 (6) ◽

pp. 608 ◽

Cited By ~ 4

Author(s):

Ahcene Mouassa ◽

Hamid Boucherit ◽

Benyebka Bou-Saïd ◽

Mustapha Lahmar ◽

Hamza Bensouilah ◽

...

Keyword(s):

Steady State ◽

Journal Bearing ◽

State Behavior ◽

Polar Fluid ◽

Steady State Behavior

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The Effect of Thermal Distortion on the Characteristics of Large Hydrodynamic Bearings

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/pime_proc_1988_202_110_02 ◽

1988 ◽

Vol 202 (3) ◽

pp. 219-225 ◽

Cited By ~ 1

Author(s):

P G Morton ◽

J H Johnson ◽

G D Wale

Keyword(s):

Experimental Investigation ◽

Steady State ◽

Journal Bearing ◽

Thermal Distortion ◽

Hydrodynamic Bearings ◽

Damping Coefficients ◽

Dynamic Coefficients ◽

Oil Whirl ◽

Stabilizing Effect ◽

Stiffness And Damping

An experimental investigation has been carried out on a 350 mm partial arc journal bearing to determine the steady state characteristics and the stiffness and damping coefficients. The bearing was found to distort due to thermal influences and the pressure distribution and dynamic coefficients consequently differed markedly from those obtained using standard theoretical techniques. Calculations of the speed at which resonant oil whirl develops in a rotor supported by bearings of this type show that the threshold speed is far higher using experimental coefficients than theoretical coefficients. It is concluded that thermal distortion has a significant stabilizing effect on large hydrodynamic bearings.

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Effect of Surface Roughness on the Pressure Generation in a Finite Rough Hydrodynamic Journal Bearing under Micropolar Lubrication in Steady-State

Reason-A Technical Journal ◽

10.21843/reas/2016/39-53/158775 ◽

2016 ◽

Vol 15 (0) ◽

pp. 39

Author(s):

Gautam Kumar ◽

Sujeet Kumar Jha ◽

Ujjal Baidya ◽

Santanu Das ◽

Sanjoy Das

Keyword(s):

Surface Roughness ◽

Steady State ◽

Journal Bearing ◽

Hydrodynamic Journal Bearing ◽

Micropolar Lubrication ◽

Effect Of Surface

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Characterization of a DNA polymerase from the hyperthermophile archaea Thermococcus litoralis. Vent DNA polymerase, steady state kinetics, thermal stability, processivity, strand displacement, and exonuclease activities.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)53949-1 ◽

1993 ◽

Vol 268 (3) ◽

pp. 1965-1975

Author(s):

H. Kong ◽

R.B. Kucera ◽

W.E. Jack

Keyword(s):

Thermal Stability ◽

Steady State ◽

Dna Polymerase ◽

Strand Displacement ◽

Thermococcus Litoralis ◽

Steady State Kinetics

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Effects of slide-to-roll ratio and varying velocity on the lubrication performance of grease at low speed

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650121993362 ◽

2021 ◽

pp. 135065012199336

Author(s):

Yiming Han ◽

Jing Wang ◽

Xuyang Jin ◽

Shanshan Wang ◽

Rui Zhang

Keyword(s):

Steady State ◽

Critical Speed ◽

Industrial Applications ◽

Transient Effects ◽

Disintegration Time ◽

Low Speed ◽

Existence Time ◽

Pure Rolling ◽

Lubrication Performance ◽

Long Time

Under steady-state pure rolling conditions with low speed, the thickener fiber agglomerations can be maintained for a long time, generating a beneficial thicker film thickness. However, in industrial applications, motions with sliding or transient effects are very common for gears, rolling-element bearings or even chain drives, evaluation of the grease performance under such conditions is vital for determining the lubrication mechanism and designing new greases. In this project, optical interferometry experiments were carried out on a ball-disk test rig to study the disintegration time of the grease thickener agglomerations with the increase of the slide-to-roll ratio under steady-state and reciprocation motions. Under steady-state conditions, the thickener fiber agglomeration can exist for a while and the time becomes shorter with the increase of the slide-to-roll ratio above the critical speed. Below the critical speed, the thickener fiber can exist in the contact in the form of a quite thick film for a very long time under pure rolling conditions but that time is decreased with the increase of the slide-to-roll ratio. The introduction of the transient effect can further reduce the existence time of the thickener.

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