Method and apparatus for nondestructive inspection utilizing phase integration and recording of induced vibrating nodal patterns
US5410406A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 1, 1993 |
| Grant date | Apr 25, 1995 |
| Priority date | — |
| Expiry date | Feb 1, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/2694
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A semi-monocoque structure is nondestructively tested by affixing an exciter to the outer skin of the structure for causing it to vibrate with an out-of-plane motion in a nodal pattern. Sensors either attached to or spaced from the outer surface provide signals representative of phase and acceleration information at likely anti-nodal points from which a computer-programmed controller senses resonant frequencies and amplitude of displacement. The controller automatically scans the excitation frequency through a predetermined range, and upon sensing a resonant frequency examines the signal to ascertain phase and amplitude of displacement of the anti-nodes and automatically adjusts their amplitude of displacement until the anti-nodes are optimized to be either bi-concave or concave/convex. When it has sensed optimum conditions, the controller twice triggers the Pockels cell of a double-pulse holographic camera at times of maximum plus and maximum minus displacement, respectively, whereby the resulting overlaid holograms are synchronized to points of maximum displacement of the anti-nodal pattern. It is from the fringe map of resulting interference patterns contouring the anti-nodal pa…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.