Method and apparatus for measuring internal mechanical stress of a ferromagnetic body by determining the third harmonic of the induction
US5047717A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 4, 1989 |
| Grant date | Sep 10, 1991 |
| Priority date | — |
| Expiry date | Dec 4, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L1/127
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for measuring the mechanical internal stress of a body of ferromagnetic material includes generating a sinusoidal magnetic field at given site of a ferromagnetic body. First and second amplitudes of the third harmonic component of the induction at first and second measuring sites at the body being mutually spaced apart by an angle of 90.degree. with respect to the given site, are measured. An associated first curve from a first predetermined family of curves representing the third harmonic component of the induction as a function of the mechanical stress for the first amplitude, is located. An associatead second curve from a second predetermined family of curves representing the third harmonic component of the induction as a function of the mechanical stress for the second amplitude, is located. Especially the first family of curves is associated with a first predetermined measuring direction or a direction parallel thereto and the second family of curves is associated with a second measuring direction perpendicular to the first predetermined measuring direction. A point of intersection of the first and the second curves is determined. A given direction is de…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.