ROTATIONAL STATISTICAL VIBRATION ANALYSIS EMPLOYING SIDEBANDS AND/OR WEIGHTING

• US 3,758,758 A
• Filed: 03/10/1972
• Issued: 09/11/1973
• Est. Priority Date: 03/10/1972
• Status: Expired due to Term

• Current Assignee: Albert J. Wyrostek, John E. Games
• Original Assignee: Albert J. Wyrostek, John E. Games
• Inventors: Games, John E., Wyrostek, Albert J.
• Primary Examiner(s): Gruber, Felix D.
• Assistant Examiner(s): Smith, Jerry
• Application Number:
  US05/233,654
• Time in Patent Office: 550 Days
• Field of Search: 235/151,151.3,151.31 73/67,67.1,67.2,71.4 324/77A,77B 340/261
• US Class Current: 702/56
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G01M 7/00 Vibration-testing of structures; Shock-testing of structures G01M9/00 takes precedence
• CPC Class Codes: G01M 7/025 Measuring arrangements

Abstract

A method of statistical analysis of the vibrational characteristics of rotary machinery includes a mechanical analysis of the involved machinery to identify pertinent frequencies therein, such as gear mesh frequencies, together with sidebands of pertinent frequencies created by FM modulation due to imperfections of parts; selective, narrow band filtering of vibrational response of the machinery, at frequency bands including fundamental frequencies, harmonics thereof and certain upper and lower sidebands of each; statistical analysis to determine standard deviations from normal responses and choice of integral numbers thereof to be taken as indicative of degradation; and weighting of the results of the test in accordance with analytical evaluation of the various responses in indicating the health of the apparatus under test. A typical system for performing vibrational analysis in a helicopter, with on-line airborne equipment or ground based equipment, employing a general purpose digital computer, and typical logic flow of a related general purpose computer are also disclosed.

Claims

1. In a method of vibrational analysis which includes comparision of coefficients of selected frequency bands, in a complex wave representing the magnitude of vibration at a point on rotary machinery, with values representing magnitudes of vibration taken as limits of magnitude of acceptable vibration, the improvement comprising:

determining a distinct coefficient for each of a plurality of frequency bands, at least two of said frequency bands comprising respective sidebands of a fundamental or harmonic gear mesh frequency.

2. In the method of claim 1, the additional improvement which comprises weighting the occurrence of exceedances of coefficients above the upper limit of acceptable performance magnitudes.

3. In a method of vibrational analysis, for determination of not only faulty gears, but faulty bearings, which includes comparison of coefficients of selected frequency bands, in a complex wave representing the magnitude of vibration at a point on rotary machinery, with values representing magnitudes of vibration taken as limits of magnitude of acceptable vibration, the improvement comprising:

determining a distinct coefficient for each of a plurality of frequency bands, at least two of said frequency bands comprising respective sidebands of a fundamental or harmonic gear mesh frequency.

4. In the method of claim 3, the additional improvement which comprises weighting the occurrence of exceedances of coefficients above the upper limit of acceptable performance magnitudes to allow fault isolation, and greatly reduce the amount of data storage by rating most bands at zero.