Crack detection method for shaft at rest
US5068800A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 19, 1990 |
| Grant date | Nov 26, 1991 |
| Priority date | — |
| Expiry date | Sep 19, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/2693
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The presence, size and location of a crack in a shaft is determined by comparing actual measured natural frequencies of the shaft system with the results of an analytical model. From a multi-station analytical model of an uncracked shaft system, natural frequencies and associated mode shapes are derived. A suspected axial location of a crack is defined, and a natural frequency of interest is selected which has an associated mode shape exhibiting significant localized bending at the suspected axial location of the crack and at a site of response measurement. The analytical model is modified to include a representation of an asymmetric crack at the suspected crack location, and a predicted split and downward shift of a lateral natural frequency of interest and/or a predicted downward shift of a torsional natural frequency of interest as a function of crack depth is calculated from the modified model. The actual shaft system is subjected to an excitation force, and vibrational response measurements are taken. A fast Fourier transform analyzer derives a frequency response function from the measurements which indicates the actual natural frequencies of the shaft system. A comparison of …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.