System and method for locating material fatigue using multiple sensors

• US 5,293,555 A
• Filed: 05/24/1991
• Issued: 03/08/1994
• Est. Priority Date: 05/24/1991
• Status: Expired due to Fees

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Anthony, Michael
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): ZANELLI, MICHAEL J
• Application Number:
  US07/705,247
• Time in Patent Office: 1,019 Days
• Field of Search: 364/507, 364/508, 364/559, 364/551.01, 73/577, 73/583, 73/587
• US Class Current: 702/36
• CPC Class Codes: G01M 5/0033 by determining damage, crack or wear
• CPC Class Codes: G01M 5/0066 by exciting or detecting vibration or acceleration vibration testing of structures G01M7/00
• CPC Class Codes: G01N 2291/106 one or more transducer arrays
• CPC Class Codes: G01N 29/075 by measuring or comparing phase angle measuring frequencies or phase angles per se G01R23/00, G01R25/00
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01V 1/001 Acoustic presence detection

Abstract

A system for locating a fatigue point on a structure (10) employing a smart sensor patch (12) having three triangularly adjacent acoustic sensors (40 a,b,c). The smart sensor patch (12) has a local processor (34) associated therewith, which triangulates the location of the fatigue point.

Claims

1. A system for locating a fatigue point on a structure wherein the emergence of the fatigue point propagates an acoustic wave through the structure, the system comprising:

at least one sensor patch, having a base layer, attached to the structure;

three triangularly adjacent sensor means, attached to said base layer of said sensor patch, for generating signals in response to receiving the incoming propagated acoustic wave;

processing means, located on said sensor patch and coupled to each of said sensor means, for determining the location of the fatigue point on the structure as a function of said generated signals from said sensor means;

a plurality of said sensor patches and a plurality of processing means, each sensor patch having a processing means associated therewith; and

a central processor means for collecting said determined fatigue point locations from each of said processing means.

2. The system of claim 1 wherein said processing means determines the location of the fatigue point by comparing the phase difference between said signals generated by said sensor means.

3. The system of claim 1 wherein said sensor means are equidistantly triangularly adjacent.

4. The system of claim 1 wherein said base layer of said sensor patch is flexible and resilient.

5. The system of claim 1 wherein said sensor means are piezoelectric transducers.

6. A system for locating a fatigue point on a structure wherein an acoustic signal is propagated through the structure when the fatigue point emerges, the system comprising:

a plurality of sensor patches attached to the structure, each sensor patch having a base layer and three triangularly adjacent acoustic sensors attached to said base layer, wherein each acoustic sensor generates a signal in response to receiving the propagated acoustic signal;

a plurality of processing means, one said processing means located on each of said sensor patches, each said processing means being coupled to said acoustic sensors on said sensor patch, for determining the location of the fatigue point in relation to the position of said sensor patch on the structure; and

a central processing means for collecting said determined relative fatigue point locations from each of said processing means.

7. A system of claim 6 wherein each of said processing means determines the relative location of the fatigue point in relation to the position of said sensor patch by determining the phase difference between said generated signals from said acoustic sensors on said sensor patch.

8. A system of claim 6 wherein said base layer of said sensor patch is flexible and resilient.

9. A system of claim 6 wherein said acoustic sensors are comprised of piezoelectric transducers.

10. A system of claim 6 wherein said acoustic sensors are equidistantly triangularly adjacent.

11. A method for locating a fatigue point on a structure, the method comprising:

attaching three triangularly adjacent acoustic sensor to a sensor patch;

attaching a processor to said sensor patch;

attaching said sensor patch to the surfaces of the structure;

receiving an acoustic signal at said acoustic sensors, said acoustic signal being propagated by the emergence of a fatigue point on the structure;

generating an electric signal from each of said acoustic sensors in response to said receiving of said acoustic signal;

coupling said generated signals to said processor;

using said processor to compute the phase difference between said generated signals from each of said acoustic sensors;

attaching a plurality of said sensor patches to the structure;

determining the location of the fatigue point in relation to the location of each of said sensor patches;

coupling a central computer means to each of said processors on said sensor patches;

determining the location of the fatigue point as a function of said determined relative fatigue point locations transmitted from said processors to said central computer means; and

determining the location of the fatigue point as a function of said computed phase difference.

12. A method of claim 11 wherein said acoustic sensors are equidistantly triangularly adjacent.

13. A method of claim 11 wherein said sensor patch is attached to the structure by an adhesive.

14. A method of claim 11 wherein said sensor patch has a flexible and resilient base layer which is attached to the structure and upon which is attached said acoustic sensors.

15. A method of claim 11 wherein said acoustic sensors are piezoelectric transducers.