Method and apparatus for monitoring structural fatigue and use

• US 20040025595A1
• Filed: 12/27/2002
• Published: 02/12/2004
• Est. Priority Date: 06/29/2000
• Status: Active Grant

• Current Assignee: University College London (University of London)
• Original Assignee: University College London (University of London)
• Inventors: Brennan, Feargal Peter
• Granted Patent: US 6,928,881 B2
• Time in Patent Office: Days
• US Class Current: 73/787
• CPC Class Codes: G01M 5/0033 by determining damage, crack or wear
• CPC Class Codes: G01M 5/0083 by measuring variation of impedance, e.g. resistance, capacitance, induction

Abstract

An electronic stress monitoring device (1) is provided that is arranged to detect and record measurements of stress experienced by a structure (2) to which the stress history unit is attached, with the measurement and recordal of stress occurring at substantially the same location. The stress monitoring unit (1) is also arranged to process the detected readings of stress to determine when significant structural events are occurring within the structure (2) to which it is attached. Data indicative of these events are recorded within the stress monitoring device (1). Periodically data recorded within the stress monitoring device (1) is obtained by a data reader (4) and then transmitted to a computer (6) for subsequent analysis.

Claims

1. Apparatus for recording data identifying significant events experienced by structure separate from said apparatus, said apparatus comprising:

a housing adapted to be attached to a structure;

stress detection means mounted in said housing, said stress detection means operable in use when said housing is attached to a structure to detect stresses experienced by the structure to which said housing is attached;

processing means for determining from readings of stress detected by said stress detection means whether a significant structural event has occurred; and

recording means for recording means for recording data indicative of significant structural events determined by said determination means.

2. Apparatus in accordance with claim 1, wherein said determination means comprises:

storage means for storing a plurality of readings of stress by said stress detection means; and

processing means for processing readings of stress stored within said storage means to determine whether a significant structural event has occurred.

3. Apparatus in accordance with claim 2, wherein said processing means is arranged to identify as significant structural events occurrences of readings associated with maximal or minimal detected stress.

4. Apparatus in accordance with claim 2 or claim 3 wherein said processing means is arranged to identify as significant structural events time periods in which detected stressed are substantially constant.

5. Apparatus in accordance with any preceding claim wherein said stress detection means further comprises filtering means wherein said filtering means is arranged to output as readings of stress, readings obtained by is said stress detection means determined to differ from previous readings of stress by at least a predetermined threshold.

6. Apparatus in accordance with any preceding claim further comprising clock means wherein said recording means is arranged to record relative timings of said significant structural events determined by said determining means.

7. Apparatus in accordance with any preceding claim wherein said recording means is arranged to record as data identifying a significant structural event, readings of stress obtained by said stress detection means which result in said significant structural event determined by said determining means.

8. Apparatus in accordance with claim 7 further comprising calculation means for determining a calculated average for recorded readings for a period of time wherein said recording means is arranged to store data identifying said calculated average.

9. Apparatus in accordance with claim 8, wherein said stress detection means is adapted to detect stress of a structure separate from said apparatus in plurality of different directions, wherein said calculation means is arranged to calculate ratios of average stresses detected for said plurality of directions and said recording means is arranged to record data indicative of said ratios.

10. Apparatus in accordance with any preceding claim further comprising output means for outputting data recorded within said memory.

11. Apparatus in accordance with any preceding claim, wherein said housing is arranged to contain the rest of said apparatus.

12. Apparatus for obtaining measurement of stress experienced by a structure separate from said apparatus, said apparatus comprising:

housing defining a cavity;

electronic stress detection means contained within said cavity, said stress detection means being adapted to detect variations in stress of a structure extending across said cavity;

recording means provided within said cavity for recording a plurality of readings of stress detected by said stress detection means; and

conduction means, provided within said cavity for transferring detected variations in stress for recordal by said recording means.

13. Apparatus in accordance with claim 12, further comprising processing means for processing detected variations in stress prior to recorded by said recording means, wherein said processing means is arranged to amplify detected variations in stress received from said conduction means.

14. Apparatus for monitoring stress, substantially as herein described with reference to the accompanying drawings.

15. A method of recording data identifying significant structural events experienced by a structure comprising the steps of:

providing electronic stress detection means for detecting stress in a structure;

providing processing means for processing obtained readings of stress;

obtaining readings of stress utilising said electronic stress detection means;

transferring said readings to said processing means to process said readings to determine whether a significant structural event has occurred; and

recording data indicative of determined significant structural events, wherein said processing means and said stress detection means are provided substantially in the same location.

16. A method of recording stress experienced by a structure comprising:

providing electronic stress detection means for detecting stress experienced by a structure;

providing recording means for recording readings obtained by said stress detection means;

obtaining readings of stress utilising said electronic stress detection means; and

recording said readings utilising said recording means wherein said recording means and said stress detection means are provided substantially in the same location.

17. A method of detecting and recording stress experienced by a structure, substantially as herein described with reference to the accompanying drawings.

18. Apparatus for obtaining measurements of stress experienced by a structure separate from said apparatus, said apparatus comprising:

a housing defining a cavity, said housing being adapted for attachment to a structure and having provided therein a hole permitting communication between the exterior of said housing and said cavity;

electronic stress detection means mounted in said hole, said electronic stress detection means being arranged when said housing is attached to a structure to detect variations in stress experienced by said structure; and

processing means, contained within said cavity of said housing for receiving and processing measurements of stress detected by said electronic stress detection means.