System and method for detecting structural damage

• US 20080294354A1
• Filed: 05/16/2008
• Published: 11/27/2008
• Est. Priority Date: 05/20/2003
• Status: Active Grant

• Current Assignee: University of Maryland Baltimore County (University of Maryland)
• Original Assignee: University of Maryland Baltimore County (University of Maryland)
• Inventors: Zhu, Weidong, Xu, Guangyao, Wong, Chun Nam, Emory, Benjamin Haynes, Zheng, Nengan
• Granted Patent: US 8,494,790 B2
• Time in Patent Office: Days
• US Class Current: 702/39
• CPC Class Codes: G01H 1/00 Measuring characteristics of vibrations in solids by using direct conduction to the detector G01H9/00, G01H11/00 take precedence
• CPC Class Codes: G01H 13/00 Measuring resonant frequency
• CPC Class Codes: G01H 5/00 Measuring propagation velocity of ultrasonic, sonic or infrasonic waves , e.g. of pressure waves
• CPC Class Codes: G01M 7/08 Shock-testing
• CPC Class Codes: G01N 2291/0258 Structural degradation, e.g. fatigue of composites, ageing of oils
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 29/12 by measuring frequency or resonance of acoustic waves measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00
• CPC Class Codes: G01N 29/227 related to high pressure, tension or stress conditions

Abstract

A system and method for detecting structural damage is provided that utilizes a general order perturbation methodology involving multiple perturbation parameters. The perturbation methodology is used iteratively in conjunction with an optimization method to identify the stiffness parameters of structures using natural frequencies and/or mode shape information. The stiffness parameters are then used to determine the location and extent of damage in a structure. A novel stochastic model is developed to model the random impact series produced manually or to generate a random impact series in a random impact device. The random impact series method or the random impact device can be used to excite a structure and generate vibration information used to obtain the stiffness parameters of the structure. The method or the device can also just be used for modal testing purposes. The random impact device is a high energy, random, and high signal-to-noise ratio system.

Claims

1. A system for determining stiffness parameters of a structure, comprising:

a sensor arranged to measure vibrations of said structure and output vibration information; and

a stiffness parameter unit for receiving said vibration information, determining natural frequency data of said structure, and determining the stiffness parameters of said structure using said natural frequency data, wherein the natural frequency data comprises at least one measured natural frequency;

wherein the stiffness parameter unit is capable of determining the stiffness parameters of said structure when the number of stiffness parameters to be determined is less than or greater than the number of measured natural frequencies.

2. The system according to claim 1, further comprising multiple sensors arranged to measure vibrations of said structure and output vibration information.

3. The system according to claim 1, wherein said stiffness parameter unit comprises an iterative processing unit.

4. The system according to claim 1, wherein said stiffness parameter unit comprises an outer iterative processing unit and an inner iterative processing unit.

5. The system according to claim 3, wherein said iterative processing unit determines said stiffness parameters using a first order perturbation process.

6. The system according to claim 3, wherein said iterative processing unit determines said stiffness parameters using a higher order perturbation process.

7-16. -16. (canceled)

17. A system, comprising:

a structure;

a sensor arranged to measure vibrations of said structure and output vibration information; and

a stiffness parameter unit for receiving said vibration information, determining natural frequency data of said structure, and determining the stiffness parameters of said structure using said natural frequency data, wherein the natural frequency data comprises at least one measured natural frequency;

wherein the stiffness parameter unit is capable of determining the stiffness parameters of said structure when the number of stiffness parameters to be determined is less than or greater than the number of measured natural frequencies.

18. The system according to claim 17, further comprising a damage information processor for receiving said stiffness parameters and outputting location of damage.

19. The system according to claim 18, wherein said damage information processor comprises a damage location processor for determining damage location information.

20. The system according to claim 18, wherein said damage information processor comprises a damage extent processor for determining extent of damage information.

21. The system according to claim 18, wherein said damage information processor comprises a damage extent processor for determining extent of damage information and a damage location processor for determining damage location information.

23. The system according to claim 17, wherein said sensor is attached to said structure.

24. The system according to claim 17, wherein said sensor is not attached to said structure.

25. The system according to claim 17, wherein said stiffness parameter unit further comprises a spectral analyzer.

26. The system according to claim 17, wherein said structure comprises a beam.

27. The system according to claim 17, wherein said structure comprises a truss.

28. The system according to claim 17, wherein said structure has a longest dimension less than 1.5 meters.

29. The system according to claim 17, wherein said structure has a longest dimension less than 2.5 meters.

30. The system according to claim 17, wherein said structure has a longest dimension less than 10 meters.

31. The system according to claim 17, wherein said structure has a longest dimension less than 50 meters.

22. (canceled)

32-35. -35. (canceled)

36. A system, comprising:

a structure;

a random impact device for inducing vibrations in said structure by impacting the structure multiple times at a common impact point and at random intervals;

a sensor arranged to measure vibrations of said structure and output vibration information; and

a stiffness parameter unit for receiving said vibration information, determining natural frequency data of said structure, and determining the stiffness parameters of said structure using said natural frequency data.

37. The system of claim 36, wherein the random impact device comprises:

a random signal generating unit for generating first and second outputs;

a random impact actuator for receiving said first and second outputs; and

an impact applicator coupled to said random impact actuator;

wherein said random impact actuator drives said impact applicator such that the force and arrival times of said impact applicator at said structure are random.

38. The system of claim 37, wherein said random impact actuator drives said impact applicator in accordance with said first and second outputs.

39. The system of claim 38, wherein the first and second outputs comprise independent random variables.

40. The system of claim 39, wherein the first and second outputs determine the force and arrival times, respectively, of the impact applicator at said structure.

41. A system for determining stiffness parameters of a structure, comprising:

a sensor arranged to measure vibrations of said structure and output vibration information; and

a stiffness parameter unit for receiving said vibration information, determining mode shape information, and determining the stiffness parameters of said structure using said mode shape information.

42. The system according to claim 41, further comprising multiple sensors arranged to measure vibrations of said structure and output vibration information.

43. The system according to claim 41, wherein said stiffness parameter unit comprises an iterative processing unit.

44. The system according to claim 41, wherein said stiffness parameter unit comprises an outer iterative processing unit and an inner iterative processing unit.

45. The system according to claim 43, wherein said iterative processing unit determines said stiffness parameters using a first order perturbation process.

46. The system according to claim 43, wherein said iterative processing unit determines said stiffness parameters using a higher order perturbation process.

47. A system for determining damage information of a structure, comprising:

a sensor arranged to measure vibrations of said structure and output vibration information;

a stiffness parameter unit for receiving said vibration information, determining mode shape information, and determining the stiffness parameters of said structure using said mode shape information; and

a damage information processor for receiving said stiffness parameters and outputting damage information.

48. A system, comprising:

a structure;

a sensor arranged to measure vibrations of said structure and output vibration information; and

a stiffness parameter unit for receiving said vibration information, determining mode shape information, and determining the stiffness parameters of said structure using said mode shape information.

49. A system, comprising:

a structure;

a random impact device for inducing vibrations in said structure;

a sensor arranged to measure vibrations of said structure and output vibration information; and

a stiffness parameter unit for receiving said vibration information, determining mode shape information, and determining the stiffness parameters of said structure using said mode shape information.

50. A system for determining damage information of a structure, comprising:

a sensor arranged to measure vibrations of said structure and output vibration information;

a stiffness parameter unit for receiving said vibration information, determining natural frequency data of said structure and mode shape information, and determining the stiffness parameters of said structure using said natural frequency data and said mode shape information; and

a damage information processor for receiving said stiffness parameters and outputting damage information.

51. A system, comprising:

a structure;

a sensor arranged to measure vibrations of said structure and output vibration information; and

a stiffness parameter unit for receiving said vibration information, determining natural frequency data of said structure and mode shape information, and determining the stiffness parameters of said structure using said natural frequency data and said mode shape information.

52. A system, comprising:

a structure;

a random impact device for inducing vibrations in said structure;

a sensor arranged to measure vibrations of said structure and output vibration information; and

a stiffness parameter unit for receiving said vibration information, determining natural frequency data of said structure and mode shape information, and determining the stiffness parameters of said structure using said natural frequency data and said mode shape information.