ADAPTIVE BASELINE DAMAGE DETECTION SYSTEM AND METHOD

• US 20150308920A1
• Filed: 04/24/2014
• Published: 10/29/2015
• Est. Priority Date: 04/24/2014
• Status: Abandoned Application

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Hedl, Radek, Sandera, Cenek
• Application Number:
  US14/261,125
• Publication Number:
  US 20150308920A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01M 7/025 Measuring arrangements
• CPC Class Codes: G01N 2291/0258 Structural degradation, e.g. fatigue of composites, ageing of oils
• CPC Class Codes: G01N 29/449 Statistical methods not provided for in G01N29/4409, e.g. averaging, smoothing and interpolation

Abstract

A system and method for detecting damage growth in a structure includes sensing, with a sensor that is coupled to the structure, a physical quantity reflecting damage growth, to thereby generate and supply a sensor signal. Features are extracted from the sensor signal to thereby generate a current feature vector. The current feature vector is assigned to either a previously created cluster or to a new cluster. A stability measure is calculated based on clusters to which the current feature vector and a predetermined number of previous feature vectors are assigned. An alarm is selectively generated based on the calculated stability measure.

Claims

1. A method of detecting damage growth in a structure, comprising the steps of:

sensing, with a sensor that is coupled to the structure, a physical quantity reflecting damage growth, to thereby generate and supply a sensor signal;

extracting a plurality of features from the sensor signal to thereby generate a current feature vector;

assigning the current feature vector to either a previously created cluster or to a new cluster;

calculating a stability measure based on clusters to which the current feature vector and a predetermined number of previous feature vectors are assigned; and

selectively generating an alarm based on the calculated stability measure.

2. The method of claim 1, wherein the step of selectively assigning comprises:

computing a distance between the current feature vector and previously created clusters;

assigning the current feature vector to a previously created cluster when the distance is less than or equal to a predetermined threshold; and

assigning the current feature vector to the new cluster when the distance is greater than a predetermined threshold.

3. The method of claim 1, further comprising calculating the predetermined threshold based on a variance of all observed clusters.

4. The method of claim 1, wherein the step of calculating the stability measure comprises:

computing an average cluster creation time; and

dividing the average cluster creation time by current time.

5. The method of claim 1, wherein the stability measure is calculated according to:

6. The method of claim 1, further comprising:

transmitting ultrasonic waves into the structure;

sensing, with the sensor, the transmitted ultrasonic waves, to thereby generate and supply the sensor signal;

7. The method of claim 6, wherein the ultrasonic waves are ultrasonic guided waves.

8. A structural health monitoring system for detecting damage growth in a structure, comprising:

a transducer configured to transmit ultrasonic waves into the structure, and to sense the transmitted ultrasonic waves to thereby generate and supply a sensor signal; and

a processor in operable communication with the transducer and coupled to receive the sensor signal therefrom, the processor configured, upon receipt of the sensor signal to;

extract a plurality of features from the sensor signal to thereby generate a current feature vector,

assign the current feature vector to either a previously created cluster or to a new cluster,

calculate a stability measure based on clusters to which the current feature vector and a predetermined number of previous feature vectors are assigne, and

selectively generate an alarm signal based on the calculated stability measure.

9. The system of claim 8, wherein the processor is further configured to:

compute a distance between the current feature vector and previously created clusters;

assign the current feature vector to a previously created cluster when the distance is less than or equal to a predetermined threshold; and

assign the current feature vector to the new cluster when the distance is greater than a predetermined threshold.

10. The system of claim 8, wherein the processor is further configured to calculate the predetermined threshold based on a variance of all observed clusters.

11. The system of claim 8, wherein the processor is further configured to:

compute an average cluster creation time; and

divide the average cluster creation time by current time.

12. The system of claim 8, wherein the processor calculates the stability measure according to:

13. The system of claim 8, wherein the ultrasonic waves are ultrasonic guided waves.

14. A structural health monitoring system for detecting damage growth in a structure, comprising:

a plurality of transducers configured to transmit ultrasonic waves into the structure, and to sense the transmitted ultrasonic waves to thereby generate and supply sensor signals; and

a processor in operable communication with the transducers and coupled to receive the sensor signals therefrom, the processor configured, upon receipt of the sensor signals to;

extract a plurality of features from each sensor signal to thereby generate a current feature vector for each sensor signal,

assign each of the current feature vectors to either a previously created cluster or to a new cluster,

calculate a stability measure based on clusters to which the current feature vectors and a predetermined number of previous feature vectors are assigned, and

selectively generate an alarm signal based on the calculated stability measure.

15. The system of claim 14, wherein the processor is further configured to:

compute a distance between the current feature vector and previously created clusters;

assign the current feature vector to a previously created cluster when the distance is less than or equal to a predetermined threshold; and

assign the current feature vector to the new cluster when the distance is greater than a predetermined threshold.

16. The system of claim 14, wherein the processor is further configured to calculate the predetermined threshold based on a variance of all observed clusters.

17. The system of claim 14, wherein the processor is further configured to:

compute an average cluster creation time; and

divide the average cluster creation time by current time.

18. The system of claim 14, wherein the processor calculates the stability measure according to:

19. The system of claim 14, wherein the ultrasonic waves are ultrasonic guided waves.