Crack detection in fracture-critical machine parts

• US 20030122682A1
• Filed: 12/28/2001
• Published: 07/03/2003
• Est. Priority Date: 12/28/2001
• Status: Active Grant

• Current Assignee: Raytheon Technologies Corporation d/b/a RTX
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Gass, Frank D., Rey, Gonzalo J.
• Granted Patent: US 6,756,908 B2
• Time in Patent Office: Days
• US Class Current: 340/679
• CPC Class Codes: C23C 4/12 characterised by the method of spraying
• CPC Class Codes: F01D 21/003 Arrangements for testing or measuring for measuring vibrations G01H
• CPC Class Codes: F01D 21/045 special arrangements in stators or in rotors dealing with breaking-off of part of rotor
• CPC Class Codes: G01N 27/20 Investigating the presence of flaws
• CPC Class Codes: G01N 27/205 in insulating materials

Abstract

A plurality of wires (33, 34; 35, 36) are disposed near the bottom (23-25) of blade root sockets (16-18) of a rotating disk 39 of a gas turbine engine by vapor deposition and etching, the wires including connections to excitation nodes (40, 42) and detection nodes (41, 43). A nearby stationary member of the engine mounts an oscillator amplifier (55) which drives a coil (57) that excites the circuitry, and a coil (62) drives an amplifier (65) and a processor (67) which provides an indication of whether or not one or more of the wires are broken by a crack.

Claims

1. Apparatus for sensing cracks at or near the surface of a part of a machine, comprising:

(a) a layer of insulation disposed on said part;

(b) a plurality of electrical conductors formed on said layer of insulation, said conductors including at least one wire electrically connected between an excitation node and a detection node, said wire being disposed across a path along which a crack may potentially form on or near the surface of said part;

(c) excitation means disposed on a static member of said machine for exciting said conductors through said excitation node; and

(d) detection means disposed on said static member for receiving, in response to excitation of said conductors, an electrical signal through said detection node indicative of the condition of said at least one wire and for providing a signal indicative thereof.

2. Apparatus according to claim 1 wherein:

said excitation node and said detection node magnetically couple said electrical circuitry to said excitation coupling means and to said detection coupling means.

3. Apparatus according to claim 1 wherein:

said electrical conductors include at least two wires electrically connected in parallel between said nodes.

4. Apparatus according to claim 1 wherein:

said excitation node provides magnetic coupling between said conductors and said excitation means.

5. Apparatus according to claim 1 wherein:

said detection node provides electromagnetic coupling between said conductors and said detection means.

6. Apparatus according to claim 1 further comprising:

a protective layer disposed over said electrical conductors.

7. Apparatus according to claim 1 wherein said insulation and said conductors are disposed on a rotatable part.

8. Apparatus according to claim 7 further comprising:

a plurality of second electrical conductors formed on said layer of insulation, said second conductors including at least one wire electrically connected between a second excitation node disposed at the same radius as said first named excitation node on said rotatable part and a second detection node disposed at the same radius as said first-named detection node on said rotatable part.

9. Apparatus according to claim 8 wherein at least one wire of said second plurality of electrical conductors is disposed across the same path, along which a crack may potentially form, as said at least one wire of said first named plurality of electrical conductors.

10. Apparatus according to claim 8 wherein at least one wire of said second plurality of electrical conductors is disposed at a position on said rotary member other than across the same path, along which a crack may potentially form, as said at least one wire of said first named plurality of electrical conductors.