Methods and systems for analyzing the degradation and failure of mechanical systems

• US 20040030524A1
• Filed: 12/09/2002
• Published: 02/12/2004
• Est. Priority Date: 12/07/2001
• Status: Active Grant

• Current Assignee: Battelle Memorial Institute
• Original Assignee: Battelle Memorial Institute
• Inventors: Peters, Timothy J., Kirihara, Leslie J., Hatley, Darrel D., Jarrell, Donald B., Sisk, Daniel R.
• Granted Patent: US 6,853,951 B2
• Time in Patent Office: Days
• US Class Current: 702/113
• CPC Class Codes: G05B 23/0221 Preprocessing measurements, e.g. data collection rate adjustment; Standardization of measurements; Time series or signal analysis, e.g. frequency analysis or wavelets; Trustworthiness of measurements; Indexes therefor; Measurements using easily measured parameters to estimate parameters difficult to measure; Virtual sensor creation; De-noising; Sensor fusion; Unconventional preprocessing inherently present in specific fault detection methods like PCA-based methods
• CPC Class Codes: G05B 23/0283 Predictive maintenance, e.g. involving the monitoring of a system and, based on the monitoring results, taking decisions on the maintenance schedule of the monitored system; Estimating remaining useful life [RUL] preventive maintenance, i.e. planning maintenance according to the available resources without monitoring the system G06Q10/06

Abstract

Methods and systems for identifying, understanding, and predicting the degradation and failure of mechanical systems are disclosed. The methods include measuring and quantifying stressors that are responsible for the activation of degradation mechanisms in the machine component of interest. The intensity of the stressor may be correlated with the rate of physical degradation according to some determinable function such that a derivative relationship exists between the machine performance, degradation, and the underlying stressor. The derivative relationship may be used to make diagnostic and prognostic calculations concerning the performance and projected life of the machine. These calculations may be performed in real time to allow the machine operator to quickly adjust the operational parameters of the machinery in order to help minimize or eliminate the effects of the degradation mechanism, thereby prolonging the life of the machine. Various systems implementing the methods are also disclosed.

Claims

1. A method of operating a machine, comprising:

identifying a degradation mechanism that can affect performance of the machine;

identifying a stressor related to the degradation mechanism;

measuring a stressor intensity at multiple time intervals;

representing a degradation rate at which the degradation mechanism affects the performance of the machine as a function of the stressor intensity; and

calculating a predicted performance of the machine using the representation of the degradation rate as a function of the stressor intensity.

2. The method of claim 1, further comprising:

representing the stressor intensity as a function of time;

calculating a precursive indicator of the degradation mechanism from the representation of the stressor intensity as a function of time; and

using the precursive indicator to calculate the predicted performance.

3. The method of claim 2, further comprising adjusting operational parameters of the machine based on the precursive indicator.

4. The method of claim 1, wherein the calculating is performed by integrating the representation of the degradation rate as a function of the stressor intensity.

5. The method of claim 1, wherein the measuring and calculating are performed substantially continuously during operation of the machine.

6. The method of claim 1, further comprising calculating a remaining life of the machine using the predicted performance of the machine.

7. The method of claim 1, wherein the representing comprises:

obtaining a first measurement of machine degradation caused by the degradation mechanism;

applying the degradation mechanism at a fixed stressor intensity for a fixed period of time;

obtaining a second measurement of the machine degradation caused by the degradation mechanism; and

calculating a function that correlates the rate of degradation as determined by the first measurement and the second measurement with the fixed stressor intensity.

8. A method of operating a machine, comprising:

identifying a degradation mechanism affecting performance of the machine;

identifying a stressor related to the degradation mechanism;

measuring a stressor intensity at multiple time intervals;

representing the stressor intensity as a function of time; and

calculating a precursive indicator of the degradation mechanism from the representation of the stressor intensity as a function of time.

9. The method of claim 8, wherein the precursive indicator is the rate of change in the stressor intensity and the calculating is accomplished by calculating the first time derivative of the representation of the stressor intensity as a function of time.

10. The method of claim 8, wherein the precursive indicator is the root indicator and the calculating is accomplished by calculating the second time derivative of the representation of the stressor intensity as a function of time.

11. The method of claim 8, wherein the measuring and calculating are performed substantially continuously during operation of the machine.

12. The method of claim 8, further comprising adjusting operational parameters of the machine based on the precursive indicator.

13. The method of claim 8, further comprising calculating a predicted performance of the machine using the precursive indicator.

14. The method of claim 8, wherein multiple precursive indicators are calculated.

15. A method of operating a machine, comprising:

measuring an intensity of a stressor that can cause degradation in a machine;

calculating one or more precursive indicators using a precursive relationship between the intensity of the stressor and machine performance; and

reporting the precursive indicator, wherein the measuring, calculating, and reporting are performed substantially continuously during the operation of the machine.

16. The method of claim 15, further comprising adjusting operational parameters of the machine based on the one or more precursive indicators.

17. The method of claim 15, further comprising calculating a remaining life of the machine using the precursive relationship, the calculating being performed substantially continuously during the operation of the machine.

18. The method of claim 15, wherein one of the precursive indicators is a rate of change in the intensity of the stressor.

19. The method of claim 15, wherein one of the precursive indicators is a gradient of the intensity of the stressor.

20. A rotating machinery system, comprising:

a motor having a rotating drive shaft;

a machine component coupled to and driven by the drive shaft;

a laser light source positioned adjacent the drive shaft to produce a beam of laser light; and

one or more laser targets coupled to the motor or the machine component, the laser targets being configured to measure the displacement of the target from a beam path and being configured to take the measurements substantially continuously.

21. The system of claim 20, further comprising one or more positioning platforms on which the motor is mounted, the positioning platforms being configured to adjust the motor and the drive shaft with respect to the machine component.

22. The system of claim 20, further comprising a computer-based analysis system coupled to the one or more laser targets, the computer-based analysis system being configured to analyze the measurements of the one or more targets during operation of the motor and to calculate a vibration intensity.

23. The system of claim 22, wherein the computer-based analysis system further calculates an alignment of the drive shaft with the machine component.

24. The system of claim 22, wherein the computer-based analysis system further calculates a predicted performance of the machine component or the motor based on the vibration intensity.

25. The system of claim 22, wherein the computer-based analysis system further calculates a precursive indicator.

26. The system of claim 20, wherein the machine component is a pump.

27. A machine diagnostic and prognostic system comprising:

a machine component whose performance may be affected by vibration;

a laser light source positioned adjacent the machine component to produce a beam of laser light;

one or more laser targets coupled to the machine component, the laser targets being configured to measure the displacement of the target from a beam path; and

a computer-based analysis system coupled to the one or more laser targets, the computer-based analysis system configured to analyze the measurements of the one or more targets during operation of the motor and to calculate a vibration intensity.

28. The system of claim 27, wherein the computer-based analysis system further calculates a predicted performance of the machine component or the motor based on the vibration intensity.

29. The system of claim 27, wherein the computer-based analysis system further calculates a precursive indicator.

30. The system of claim 27, wherein the laser targets are configured to take the measurements substantially continuously.

31. A rotating machinery system, comprising:

a motor;

a rotating armature positioned within the motor;

a drive shaft coupled with the armature;

a machine component coupled with an inboard end of the drive shaft, the machine component being operated by rotation of the drive shaft;

a radial bearing through which the drive shaft extends, the radial bearing being housed in a radial bearing housing of the motor; and

one or more load cells positioned in the radial bearing housing, each of the load cells being configured to measure a force exerted on the respective load cell by the drive shaft.

32. The system of claim 31, wherein the one or more load cells are ultra-thin load cells.

33. The system of claim 31, wherein the one or more load cells are frictionally supported between the radial bearing and the radial bearing housing.

34. The system of claim 33, wherein the frictional support is accomplished by positioning the one or more load cells between an outer shim and an inner shim.

35. The system of claim 31, wherein the one or more load cells are configured to take the measurements substantially continuously.

36. The system of claim 31, further comprising a computer-based analysis system coupled to the one or more load cells, the computer-based analysis system being configured to analyze the measurements of the one or more load cells during operation of the motor and to calculate a vibration intensity.

37. The system of claim 36, wherein the computer-based analysis system further calculates a remaining operating life of the motor based on the vibration intensity.

38. The system of claim 36, wherein the computer-based analysis system further calculates a precursive indicator based on the load cell measurements.

39. The system of claim 31, further comprising:

a motor housing extension integrally connected with the motor and positioned adjacent an outboard end of the drive shaft; and

an axial load cell positioned within the motor housing extension and axially adjacent to the outboard end of the drive shaft, the axial load cell being configured to measure an axial force exerted by the drive shaft.

40. A pump, comprising:

a pump housing having an input and an output;

an impeller portion of the pump housing;

a volute portion of the pump housing, the volute portion being positioned adjacent the impeller portion and connecting with the output; and

one or more acoustic emission sensors positioned on an exterior of the pump housing, the acoustic emission sensors being configured to measure the intensity of cavitation occurring within the pump housing.

41. The pump of claim 40, wherein the acoustic emission sensors are configured to measure the intensity of the cavitation substantially continuously.

42. The pump of claim 40, wherein the one or more acoustic emission sensors comprise a single acoustic emission sensor positioned on the exterior of the pump housing adjacent an eye of the impeller portion.

43. The pump of claim 40, further comprising a computer-based analysis system coupled to the one or more acoustic emission sensors, the computer-based analysis system being configured to analyze the measurements of the one or more acoustic emission sensors during operation of the pump and to calculate a cavitation intensity.

44. The system of claim 43, wherein the computer-based analysis system further calculates a remaining operating life of the pump based on the cavitation intensity.

45. The system of claim 43, wherein the computer-based analysis system further calculates a precursive indicator based on the cavitation intensity.

46. An operations manual for operating machinery, the manual instructing an operator to:

measure an intensity of a stressor causing degradation in a machine;

calculate one or more precursive indicators using a precursive relationship between the intensity of the stressor and machine performance; and

adjust the machinery based on the one or more precursive indicators.