Accession Number : ADD017884

Title :   Optical Fiber Strain Sensor for Measuring Maximum Strain.

Descriptive Note : Patent, Filed 30 Jun 94, patented 31 Oct 95,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

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

Report Date : 31 Oct 1995

Pagination or Media Count : 7

Abstract : An optical fiber strain sensor is provided which remembers the maximum strain a structure has experienced in a given time frame. A pair of multimode optical fibers with flat ends meet end to end within a microbore capillary tube with which the fibers have frictional contact. The fibers are fastened to the structure at two points a known distance apart on either side of the capillary tube. Increasing strain in the structure pulls the fiber ends apart in proportion to the amount of strain; however, when strain is decreasing, the fibers buckle rather than move closer together. Therefore, the maximum strain is reflected as a maximum distance between the fiber ends. When the maximum strain experienced is to be measured, the free end of one fiber is connected to a light source and the free end of the other fiber is connected to a detector. The intensity of light transmitted to the detector will vary inversely with the distance apart the fiber ends are; therefore, this distance can be measured and correlated with strain to a high degree of accuracy.

Descriptors :   *FIBER OPTICS, *STRAIN GAGES, *PATENTS, *DISTANCE MEASURING EQUIPMENT, ACCURACY, BUCKLING, MULTIMODE, RANGE(DISTANCE), FRICTION, CAPILLARY TUBES

Subject Categories : Test Facilities, Equipment and Methods
      Optical Detection and Detectors
      Fiber Optics and Integrated Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE