Method and apparatus for determining in real-time the fatigue life of a structure

• US 6,449,565 B1
• Filed: 04/05/1999
• Issued: 09/10/2002
• Est. Priority Date: 04/05/1999
• Status: Expired due to Term

• Current Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Davis, Jeffrey R., Plotts, Kurt A., Budrow, Steven E.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Charioui, Mohamed
• Application Number:
  US09/286,378
• Time in Patent Office: 1,254 Days
• Field of Search: 702/42, 702/34, 702/43, 703/7, 701/14, 378/72, 735/87, 244/1.R
• US Class Current: 702/42
• CPC Class Codes: F05D 2220/323 for aircraft propulsion, e.g. jet engines
• CPC Class Codes: G07C 3/00 Registering or indicating the condition or the working of machines or other apparatus, other than vehicles

Abstract

A method and apparatus for determining the fatigue life of a structure calculate, in real time, the values for the magnitudes of the stress forces imposed at a particular location on the structure, from one or more sensed structural parameters. Also, the associated temperature values of the structure may be calculated or measured. The calculated stress data are continuously examined, in real time, to determine if the direction of their magnitude is increasing or decreasing. If a change in direction is indicated, the previously stored peak data point in the increasing direction is paired with the previously determined peak data point in the decreasing direction to form a cycle pair. The structural fatigue life is then determined, in real time, from this cycle pair.

Claims

1. A method for determining, in real time, the fatigue life of at least a portion of a structure, comprising the steps of:

determining the stress forces imposed on at least a portion of the structure;

determining, from the determined stress forces, a cycle pair comprising a pair of high and low peak magnitude values of the determined stress forces; and

determining the fatigue life of at least a portion of the structure from the determined cycle pair.

2. The method of claim 1, further comprising the step of determining a temperature of at least a portion of the structure.

3. The method of claim 2, wherein the step of determining the fatigue life of at least a portion of the structure from the determined cycle pair further comprises the step of determining the fatigue life of at least a portion of the structure from the determined temperature of at least a portion of the structure.

4. The method of claim 2, wherein the step of determining the temperature on at least a portion of the structure comprises the steps of:

sensing a temperature of at least a portion of the structure; and

calculating a temperature of at least a portion of the structure from the sensed temperature of at least a portion of the structure.

5. The method of claim 1, wherein the step of determining, from the determined stress forces, a cycle pair comprising a pair of high and low peak magnitude values of the determined stress forces further comprises the steps of:

determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction and providing a first indication of whether the determined stress forces are increasing or decreasing in direction;

comparing the determined stress forces to the provided first indication of whether the determined stress forces are increasing or decreasing in direction to determine whether the magnitudes of the determined stress forces are increasing or decreasing in direction; and

if the result of the comparing is such that the determined stress forces are opposite in direction to the provided first indication. of whether the determined stress forces are increasing or decreasing in direction, then storing a selected magnitude of the determined stress forces in the corresponding one of the increasing or decreasing directions indicated by the step of determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction.

6. The method of claim 8, wherein if the result of the comparing is such that the determined stress forces are opposite in direction to the provided first indication of whether the determined stress forces are increasing or decreasing in direction, then further comprising the steps of

determining whether the magnitudes of the determined stress forces are in the direction opposite to that of the provided first indication and providing a second indication of whether the determined stress forces are in the direction opposite to that of the provided first indication;

comparing the determined stress forces to the provided second indication to determine whether the magnitudes of the determined stress forces are in the direction of the provided first or second directions; and

if the result of the comparing is such that the determined stress forces are in the direction of the provided first indication, then storing a selected magnitude of the determined stress forces in the direction of the provided second indication, and pairing the stored selected magnitude of the determined stress forces in each one of the directions indicated by the provided first and second indications, to thereby determine the cycle pair.

7. The method of claim 1, wherein the step of determining the stress forces imposed on at least a portion of the structure comprises the steps of:

sensing one or more parameters associated with at least a portion of the structure; and

calculating the stress forces imposed on the at least a portion of the structure from the one or more sensed parameters associated with at least a portion of the structure.

8. The method of claim 1, wherein the step of determining the stress forces imposed on at least a portion of the structure comprises the step of determining, in real time, the stress forces imposed on at least a portion of the structure.

9. The method of claim 1, wherein the step of determining, from the determined stress forces, a cycle pair comprising a pair of high and low peak magnitude values of the determined stress forces comprises the step of determining, in real time, from the determined stress forces, a cycle pair comprising a pair of high and low peak magnitude values of the determined stress forces.

10. The method of claim 1, wherein the step of determining the fatigue life of at least a portion of the structure from the determined cycle pair comprises the step of determining, in real time, the fatigue life of at least a portion of the structure from the determined cycle pair.

11. The method of claim 1, wherein the step of determining the fatigue life of at least a portion of the structure from the determined cycle pair comprises the step of calculating the fatigue life of at least a portion of the structure from the determined cycle pair.

12. Apparatus for determining, in real time, the fatigue life of at least a portion of a structure, comprising:

means for determining, in real time, the stress forces imposed on at least a portion of the structure;

means for determining, in real time and from the determined stress forces, a cycle pair comprising a pair of high and low peak magnitude values of the determined stress forces; and

means for determining, in real time, the fatigue life of at least a portion of the structure from the determined cycle pair.

13. The apparatus of claim 12, further comprising means for determining a temperature of at least a portion of the structure.

14. The apparatus of claim 13, wherein the means for determining, in real time, the fatigue life of at least a portion of the structure from the determined cycle pair further comprises means for determining, in real time, the fatigue life of at least a portion of the structure from the determined temperature of at least a portion of the structure.

15. The apparatus of claim 13, wherein the means for determining the temperature on at least a portion of the structure further comprises:

means for sensing a temperature of at least a portion of the structure; and

means for calculating a temperature of at least a portion of the structure from the sensed temperature of at least a portion of the structure.

16. The apparatus of claim 12, wherein the means for determining, in real time and from the determined stress forces, a cycle pair comprising a pair of high and low peak magnitude values of the determined stress forces further comprises:

means for determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction and providing a first indication of whether the determined stress forces are increasing or decreasing in direction; and

means for comparing the determined stress forces to the provided first indication of whether the determined stress forces are increasing or decreasing in direction to determine whether the magnitudes of the determined stress forces are increasing or decreasing in direction, and if the result of the comparing is such that the determined stress forces are opposite in direction to the provided first indication of whether the determined stress forces are increasing or decreasing in direction, then for storing a selected magnitude of the determined stress forces in the corresponding one of the increasing or decreasing directions indicated by the means for determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction.

17. The apparatus of claim 16, wherein if the result of the comparing is such that the determined stress forces are opposite in direction to the provided first indication of whether the determined stress forces are increasing or decreasing in direction, then further comprising:

means for determining whether the magnitudes of the determined stress forces are in the direction opposite to that of the provided first indication, and for providing a second indication of whether the determined stress forces are in the direction opposite to that of the provided first indication; and

means for comparing the determined stress forces to the provided second indication to determine whether the magnitudes of the determined stress forces are in the direction of the provided first or second directions, and if the result of the comparing is such that the determined stress forces are in the direction of the provided first indication, then for storing a selected magnitude of the determined stress forces in the direction of the provided second indication, and for pairing the stored selected magnitude of the determined stress forces in each one of the directions indicated by the provided first and second indications, to thereby determine the cycle pair.

18. The apparatus of claim 12, wherein the means for determining, in real time, the stress forces imposed on at least a portion of the structure further comprises:

means for sensing one or more parameters associated with at least a portion of the structure; and

means for calculating the stress forces imposed on the at least a portion of the structure from the one or more sensed parameters associated with at least a portion of the structure.

19. The apparatus of claim 12, wherein the means for determining, in real time, the fatigue life of at least a portion of the structure from the determined cycle pair further comprises means for calculating the fatigue life of at least a portion of the structure from the determined cycle pair.

20. A method for determining in real time the fatigue life of at least one component of an engine comprising the steps of:

monitoring two engine parameters;

transmitting said two monitored parameters to a processing unit;

determining the stress forces imposed on said at least one engine component from said two transmitted monitored parameters;

determining from said determined stress forces a cycle pair comprising a pair of high and low peak magnitude values of the determined stress forces; and

determining the fatigue life of said at least one engine component from the determined cycle pair.

21. A method according to claim 20, further comprising:

monitoring a temperature of at least a portion of said engine; and

transmitting said monitored temperature to said processing unit.

22. A method according to claim 21, wherein said temperature monitoring step comprises monitoring in real time a compressor inlet temperature.

23. A method according to claim 21, further comprising determining said fatigue life of said at least one engine component using said monitored temperature.

24. A method according to claim 20, wherein the cycle pair determining step comprises:

determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction and providing a first indication of whether the determined stress forces are increasing or decreasing in direction;

comparing the determined stress forces to the provided first indication of whether the determined stress forces are increasing or decreasing in direction to determine whether the magnitudes of the determined stress forces are increasing or decreasing in direction; and

if the result of the comparing is such that the determined stress forces are opposite in direction to the provided first indication of whether the determined stress forces are increasing or decreasing in direction, then storing a selected magnitude of the determined stress forces in the corresponding one of the increasing or decreasing directions indicated by the step of determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction.

25. A method according to claim 24, wherein if the result of the comparing is such that the determined stress forces are opposite in direction to the provided first indication of whether the determined stress forces are increasing or decreasing in direction, then further comprising the steps of:

determining whether the magnitudes of the determined stress forces are in the direction opposite to that of the provided first indication and providing a second indication of whether the determined stress forces are in the direction opposite to that of the provided first indication;

comparing the determined stress forces to the provided second indication to determine whether the magnitudes of the determined stress forces are in the direction of the provided first or second directions; and

if the result of the comparing is such that the determined stress forces are in the direction of the provided first indication, then storing a selected magnitude of the determined stress forces in the direction of the provided second indication, and pairing the stored selected magnitude of the determined stress forces in each one of the directions indicated by the provided first and second indications, to thereby determine the cycle pair.

26. A method according to claim 20, wherein said monitoring step comprises monitoring in real time pressure at an inlet of a compressor and fan combination and monitoring in real time a speed for said combination.

27. A system for determining in real time the fatigue life of an engine component comprising:

means for monitoring two engine parameters;

means for transmitting the two monitored parameters to a processing unit;

means for determining stress forces imposed on said at least one engine component from said two transmitted parameters;

means for determining from said determined stress forces a cycle pair comprising a pair of high and low peak magnitude values of the determined stress forces; and

means for determining the fatigue life of said at least one engine component from the determined cycle pair.

28. A system according to claim 27, further comprising means for monitoring a temperature of at least a portion of said engine and means for transmitting said monitored temperature to said processing unit.

29. A system according to claim 28, wherein said temperature monitoring means comprises means for monitoring in real time a compressor inlet temperature.

30. A system according to claim 28, wherein said fatigue life determining means includes means which uses said monitored temperature to determine said fatigue life.

31. A system according to claim 27, wherein the cycle pair determining means comprises:

means for determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction and providing a first indication of whether the determined stress forces are increasing or decreasing in direction; and

means for comparing the determined stress forces to the provided first indication of whether the determined stress forces are increasing or decreasing in direction to determine whether the magnitudes of the determined stress forces are increasing or decreasing in direction, and if the result of the comparing is such that the determined stress forces are opposite in direction to the provided first indication of whether the determined stress forces are increasing or decreasing in direction, then for storing a selected magnitude of the determined stress forces in the corresponding one of the increasing or decreasing directions indicated by the means for determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction.

32. A system according to claim 31, wherein if the result of the comparing is such that the determined stress forces are opposite in direction to the provided first indication of whether the determined stress forces are increasing or decreasing in direction, then further comprising:

means for determining whether the magnitudes of the determined stress forces are in the direction opposite to that of the provided first indication, and for providing a second indication of whether the determined stress forces are in the direction opposite to that of the provided first indication; and

means for comparing the determined stress forces to the provided second indication to determine whether the magnitudes of the determined stress forces are in the direction of the provided first or second directions, and if the result of the comparing is such that the determined stress forces are in the direction of the provided first indication, then for storing a selected magnitude of the determined stress forces in the direction of the provided second indication, and for pairing the stored selected magnitude of the determined stress forces in each one of the directions indicated by the provided first and second indications, to thereby determine the cycle pair.

33. A system according to claim 27, wherein said monitoring means comprises a first sensor for sensing real time pressure at an inlet of a compressor and fan combination and a second sensor for sensing real-time speed for said combination.

34. A method for determining in real time the fatigue life of at least a portion of a structure comprising the steps of:

determining the stress forces imposed on at least a portion of the structure;

determining from the determined stress forces a cycle pair comprising a pair of high and low peak magnitude values of the determined stress forces;

determining the fatigue life of at least a portion of the structure from the determined cycle pair; and

the cycle pair determining step comprising determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction and providing a first indication of whether the determined stress forces are increasing or decreasing in direction, comparing the determined stress forces to the provided first indication of whether the determined stress forces are increasing or decreasing in direction to determine whether the magnitudes of the determined stress forces are increasing or decreasing in direction; and

if the result of the comparing is such that the determined stress forces are increasing or decreasing in direction, then storing a selected magnitude of the determined stress forces in the corresponding one of the increasing or decreasing directions indicated by the step of determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction.

35. An apparatus for determining in real time the fatigue life of at least a portion of a structure comprising:

means for determining in real time the stress forces imposed on at least a portion of the structure;

means for determining in real time and from the determined stress forces a cycle pair comprising a pair of high and low peak magnitude values of the determined stress forces;

means for determining in real time the fatigue life of at least a portion of the structure from the determined cycle pair; and

said cycle pair determining means comprising means for determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction and providing a first indication of whether the determined stress forces are increasing or decreasing in direction and means for comparing the determined stress forces to the provided first indication of whether the determined stress forces are increasing or decreasing in direction to determine whether the magnitudes of the determined stress forces are increasing or decreasing in direction, and if the result of the comparing is such that the determined stress forces are opposite in direction to the provided first indication of whether the determined stress forces are increasing or decreasing in direction, then for storing a selected magnitude of the determined stress forces in the corresponding one of the increasing or decreasing directions indicated by the means for determining whether the magnitudes of the determined stress forces are increasing or decreasing in direction.