System and method for detecting structural damage

• US 8,494,790 B2
• Filed: 05/16/2008
• Issued: 07/23/2013
• 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: Xu, Guangyao, Zhu, Weidong, Wong, Chun Nam, Zheng, Nengan, Emory, Benjamin Haynes
• Primary Examiner(s): NGHIEM, MICHAEL P
• Application Number:
  US12/153,348
• Publication Number:
  US 20080294354A1
• Time in Patent Office: 1,894 Days
• Field of Search: 702 34- 36, 702/56, 702/75
• US Class Current: 702/56
• 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 configured to receive said vibration information output by said sensor, to determine natural frequency data of said structure, and to determine 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 configured to determine the stiffness parameters of said structure when a number of stiffness parameters to be determined is greater than a 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 3, wherein said iterative processing unit determines said stiffness parameters using a first order perturbation process.

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

6. The system according to claim 1, wherein said stiffness parameter unit comprises an outer iterative processing unit and an inner iterative processing unit which operate using a first order perturbation approach or a higher order perturbation approach and which operate using a gradient method or a quasi-Newton method.

7. The system according to claim 1, further comprising a damage information processor configured to receive said stiffness parameters generated by said stiffness parameter unit, to determine a location of damage, and to output a location of said damage.

8. The system according to claim 7, wherein said damage information processor comprises a damage extent processor configured to determine an extent of damage at said location of said damage.

9. The system according to claim 1, wherein said stiffness parameter unit is configured to determine the stiffness parameters of said structure using only said natural frequency data.