Measurement and Analysis of Shipboard Vibrations

Excessive shipboard vibrations can cause structural and machinery failures, crew discomfort and fatigue, and increased maintenance requirements for shipboard systems. In many cases ship construction specifications require the shipyard to demonstrate "acceptable " levels of vibration using measurements completed during sea trials. This paper provides an overview of standards for these measurements and modern techniques used to collect and analyze the specified vibration data. A brief discussion of the types of vibrations found on ships and their causes is followed by a review of codes, guides and standards for vibration measurement. Instrumentation suitable for measurement of each type of vibration response is described and the design of a typical trial measurement system is presented. Techniques for analyzing and presenting trial results are reviewed and compared with analysis methods specified by SNAME, ISO and NAVSEA. Finally, a discussion of potential problems faced by an owner and shipyard in developing and meeting a vibration measurement specification is offered.

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Experience With the Non-Contacting Blade Vibration Measurement Method Using Two Sensors in a Low Pressure Model Steam Turbine

2002 International Joint Power Generation Conference ◽

10.1115/ijpgc2002-26070 ◽

2002 ◽

Author(s):

Zechun Hu ◽

Gerhard Eyb ◽

David Regnery

Keyword(s):

Steam Turbine ◽

Measurement System ◽

Low Pressure ◽

Vibration Measurement ◽

Mode Shapes ◽

Blade Vibration ◽

Vibration Data ◽

Operation Conditions ◽

Excited Vibration ◽

Extended Operation

This paper presents an application of a non-contacting blade tip timing measurement system using two-sensor method (so-called BSSM) at a low-pressure model steam turbine to investigate dynamic blade stress in extended operation conditions (so-called windage). An analysis method to identify the vibration frequencies and to determine the response amplitudes for the first few excited vibration mode shapes is described in detail. Objective of this paper is to discuss the performance and inherent limitations of the non-contacting measurement system. For that the BSSM results were compared with the blade vibration data obtained from strain gauges. Some experiences and suggestions are also made to improve the reliability and accuracy of this measurement system.

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Wavelet Analysis of Vibration: Part 1—Theory

Journal of Vibration and Acoustics ◽

10.1115/1.2930443 ◽

1994 ◽

Vol 116 (4) ◽

pp. 409-416 ◽

Cited By ~ 225

Author(s):

D. E. Newland

Keyword(s):

Signal Analysis ◽

Spectral Composition ◽

Vibration Measurement ◽

Harmonic Wavelets ◽

Time Frequency ◽

Orthogonal Wavelets ◽

Vibration Data ◽

Measurement And Analysis ◽

Frequency Map ◽

Selection Of

Wavelets provide a new tool for the analysis of vibration records. They allow the changing spectral composition of a nonstationary signal to be measured and presented in the form of a time-frequency map. The purpose of this paper, which is Part 1 of a pair, is to introduce and review the theory of orthogonal wavelets and their application to signal analysis. It includes the theory of dilation wavelets, which have been developed over a period of about ten years, and of harmonic wavelets which have been proposed recently by the author. Part II is about presenting the results on wavelet maps and gives a selection of examples. The papers will interest those who work in the field of vibration measurement and analysis and who are in positions where it is necessary to understand and interpret vibration data.

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