Accession Number : ADD018567

Title :   Optical Fiber Strain-To-Failure Sensor.

Descriptive Note : Patent, Filed 23 Oct 95, patented 17 Jun 97

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Bobb, Lloyd C ; Krumboltz, Howard D

Report Date : 17 Jun 1997

Pagination or Media Count : 5

Abstract : A sensor and method are disclosed for determining if a region, defined by two end points, in a structure has exceeded a predetermined amount of strain. The sensor has an optical waveguide which has two ends for receiving and emitting light and which is fixable at two locations thereon to respective ones of the end points to define a sensing region therebetween. The sensing region has a first portion with a first length and a first cross-sectional area, and a second portion with a second length and a second cross-sectional area which is smaller than the first cross-sectional area. The lengths and cross-sectional areas are sized so that the optical waveguide has a strain failure point equal to the predetermined amount of strain. The lengths and cross-sectional areas are approximately sized according to the formula R=alpha+1/ (alpha/beta+1), wherein R is the ratio of the amount of strain in the second portion which will cause the optical waveguide to fail to the predetermined amount of strain in the structure, alpha is the ratio of the length of the first portion to the length of the second portion, and beta is the ratio of the cross-sectional area of the first portion to the cross-sectional area of the second portion.

Descriptors :   *FIBER OPTICS, *OPTICAL DETECTORS, *PATENTS, STRAIN(MECHANICS), OPTICAL WAVEGUIDES, STRAIN GAGES, FAILURE(MECHANICS)

Subject Categories : Optical Detection and Detectors
      Fiber Optics and Integrated Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE