Binary code symbol for non-linear strain measurement and apparatus and method for analyzing and measuring strain therewith

• US 7,533,818 B2
• Filed: 06/28/2005
• Issued: 05/19/2009
• Est. Priority Date: 06/28/2005
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: Direct Measurements, Inc.
• Inventors: Ranson, William F., Hovis, Gregory L., Vachon, Reginald I.
• Primary Examiner(s): ST CYR, DANIEL
• Application Number:
  US11/167,558
• Publication Number:
  US 20060289652A1
• Time in Patent Office: 1,421 Days
• Field of Search: 235/462.01, 235/462.09, 235/462.15, 235/462.25
• US Class Current: 235/462.09
• CPC Class Codes: G01B 11/165 by means of a grating deformed by the object
• CPC Class Codes: G01L 5/0047 measuring forces due to residual stresses
• CPC Class Codes: G01M 5/0091 by using electromagnetic excitation or detection

Abstract

A binary code symbol for non-linear strain measurement designed specifically for perimeter-based deformation and strain analysis. The symbol is rectangular with a continuous outer perimeter, two data regions along adjacent sides of the rectangle and a utility region adjacent each side opposite the data regions. Each data region is made up of a number of data cells, and each utility region is made up of utility cells with alternating appearance. The inner half of the utility regions can be used to store auxiliary information and/or codes. There are two distinct finder cells on opposite corners of the rectangle, which can be used to orient the symbol. A non-linear strain gage for measuring the strain on an object under load in accordance includes a target, a sensor, and a computer, wherein the target is a binary code symbol.

Claims

1. A rectangular binary code symbol for non-linear strain measurement, comprising:

a solid, continuous outer perimeter;

first and second data regions along adjacent sides of the outer perimeter, each data region comprising a number of data cells, each data cell representing a single bit of binary data, the first and second data regions having inner sides inwardly offset from the outer perimeter;

first and second utility regions along adjacent sides of the outer perimeter opposite the first and second data regions, each utility region comprising a number of utility cells of alternating appearance, the first and second utility regions having inner sides inwardly offset from the outer perimeter;

an inner perimeter defined by the inner sides of the first and second data regions and the first and second utility regions;

first and second finder cells at opposite corners of the rectangle; and

inner and outer quiet regions distinguishing the first and second data regions, the first and second utility regions, and the first and second finder cells from their background, the outer quiet region being outward of the outer perimeter and the inner quiet region being inward of the inner perimeter.

2. The binary code symbol of claim 1, wherein the first and second utility regions each have an inner half storing at least one of auxiliary information and codes.

3. The binary code symbol of claim 1, wherein the symbol is symmetric and the first and second data regions are identical to one another for encoded-data redundancy.

4. The binary code symbol of claim 1, wherein the binary data represented by the data cells are encoded using an error-correcting code algorithm.

5. The binary code symbol of claim 4, wherein the error-correcting code algorithm combines vector-space mathematics and set theory to convert numeric quantities into encoded values that provide limited self-checking and self-correcting capability during decoding.

6. The binary code symbol of claim 5, wherein the algorithm used is a Hamming 7-4 technique.

7. A non-linear strain gage comprising:

a target associated with an object for which at least one of strain and fatigue damage is to be measured and emitting a detectable physical quantity, the target comprising a rectangular binary code symbol for non-linear strain measurement, the binary code symbol including;

a solid, continuous perimeter;

first and second data regions along adjacent sides of the perimeter, each data region comprising a number of data cells, each data cell representing a single bit of binary data;

first and second utility regions along adjacent sides of the perimeter opposite the first and second data regions, each utility region comprising a number of utility cells of alternating appearance;

first and second finder cells at opposite corners of the rectangle; and

inner and outer quiet regions distinguishing the first and second data regions, the first and second utility regions, and the first and second finder cells from their background;

sensor means for pre-processing the detectable physical quantity emitted by the target and output data representing the physical quantity, the sensor means being compatible with the detectable physical quantity;

means for analyzing the data output by the sensor means to define the binary code symbol; and

means for measuring the strain on the object directly based on the pre-processed and analyzed data.

8. The non-linear strain gage of claim 7, further comprising means for utilizing the strain measurement to provide information on at least one of fatigue damage and strain hysteresis for materials of known and unknown mechanical properties.

9. The non-linear strain gage of claim 7, further comprising means for utilizing the strain measurement to assist in component lifecycle management.

10. The non-linear strain gage of claim 7, further comprising means for utilizing the strain measurement based on collected damage accumulation data.

11. The non-linear strain gage of claim 7, wherein the binary code symbol is defined a priori by manufacture.

12. The non-linear strain gage of claim 7, wherein the target is identified in a pre-existing pattern that defines the binary code symbol.

13. A method of measuring strain on an object directly, comprising the steps of:

associating a binary code symbol with an object in such a way that deformation of the binary code symbol and deformation under load of the object bear a one-to-one relationship, wherein the binary code symbol emits a detectable physical quantity and includes;

a solid, continuous perimeter;

first and second data regions along adjacent sides of the perimeter, each data region comprising a number of data cells, each data cell representing a single bit of binary data;

first and second utility regions along adjacent sides of the perimeter opposite the first and second data regions, each utility region comprising a number of utility cells of alternating appearance;

first and second finder cells at opposite corners of the rectangle; and

inner and outer quiet regions distinguishing the first and second data regions, the first and second utility regions, and the first and second finder cells from their background;

identifying the changes in the binary code symbol as a function of time and change in the load applied to the object; and

translating the changes in the binary code symbol into a direct measurement of strain.

14. The method of claim 13, wherein the binary code symbol is defined a priori by manufacture and the associating step comprises applying the binary code symbol to the object.

15. The method of claim 13, wherein the associating step comprises identifying the binary code symbol a priori.

16. The method of claim 13, further comprising the step of utilizing the strain measurement to provide information on at least one of fatigue damage and strain hysteresis for materials of known and unknown mechanical properties.

17. The method of claim 13, further comprising the step of utilizing the strain measurement to assist in component lifecycle management.

18. The method of claim 13, further comprising the step of utilizing the strain measurement based on collected damage accumulation data.