Hull monitoring apparatus and method

• US 5,425,275 A
• Filed: 05/21/1993
• Issued: 06/20/1995
• Est. Priority Date: 06/01/1990
• Status: Expired due to Fees

• Current Assignee: Tolo, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: James Lockshaw
• Inventors: Lockshaw, James
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US08/065,927
• Time in Patent Office: 760 Days
• Field of Search: 73/774-776, 73/786, 73/802, 324/519, 324/523, 324/522, 428/343, 428/344, 428/351, 428/354, 428/356, 428/148
• US Class Current: 73/775
• CPC Class Codes: B63B 71/00 Designing vessels; Predicting their performance
• CPC Class Codes: G01B 7/18 using change in resistance
• CPC Class Codes: G01L 1/142 using capacitors
• CPC Class Codes: G01L 1/20 by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids of piezo-resistive materials G01L1/18; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
• 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
• CPC Class Codes: Y10T 428/2804 Next to metal
• CPC Class Codes: Y10T 428/2848 Three or more layers

Abstract

For detecting strains or breaks in the surface of a boat hull or other structure, the surface is covered with non-intersecting lengths of tape adhered to the surface. The tape has an inner strip of conductive elastomer and an outer strip of the same material, and between them a corrugated layer of copper foil. Both strips and the foil are insulated from each other and the outside. The strips and foil layer are connected to electrical resistance and capacitance measuring devices, which monitor any changes in the electrical properties of the tape lengths, caused by strain or breaking of the surface. Because of the corrugations, the foil will not change its resistance when the tape is elongated or compressed.

Claims

1. Detecting tape comprising:

a conductive inner strip having an electrical resistance varying with its elongation and compression, a conductive outer strip adjacent said inner strip, said outer strip having an electrical resistance varying with its elongation and compression, a conductive foil layer disposed intermediate said inner and outer strips, and said inner strip, outer strip, and foil layer being insulated from each other by dielectric film, an electrical connector leading from each of said inner strip and said outer strip and said conductive foil, whereby said tape may be adhered to a structure wall surface subject to strain and breakage, and elongation or compressional dimensional change of the tape at a point, due to strain and breakage of said wall surface adhered to said tape at said point results in changes in the electrical properties of tape detectable by electrical measuring devices connected to said electrical connectors.

2. The detecting tape according to claim 1, wherein said inner strip comprises conductive elastomer.

3. The detecting tape according to claim 1, wherein said outer strip comprises conductive elastomer.

4. Detecting tape comprising:

a conductive inner strip having an inner strip electrical resistance varying with elongation and compression of the inner strip, a conductive outer strip adjacent the inner strip having an outer strip electrical resistance varying with elongation and compression of the outer strip, a conductive foil layer intermediate said inner strip and said outer strip, and dielectric film insulating said inner strip, said outer strip, and said foil layer from each other, whereby the tape may be adhered to a structure wall surface subject to strain and breakage, and dimensional change of the tape at a point, due to strain and breakage of surface adhering to the tape at the point, will result in changes in the electrical properties of tape detectable by electrical measuring devices, said foil layer being corrugated transverse to the linear extension of said tape, whereby elongation and compression of the tape will not change the cross sectional area of said foil layer, and foil layer electrical resistance is not be altered by said elongation and compression.