In-situ strain monitoring in composites using an embedded extrinsic Fabry-Perot interferometric sensor and a CCD detection system

摘要

This paper reports on the use of a multimode extrinsic fiber Fabry-Perot interferometric sensor for quasi-static and dynamic fatigue loading experiments. A surface mounted extensometer was also used to measure the strain in the composite as a function of applied load. Excellent correlation was obtained between the strain data from the extensometer and the embedded EFPI sensor. With reference to dynamic loading, the sensor was found function reliable up to 1,600,000 cycles when the fatigue test was terminated. The fatigue tests were carried out using a peak stress of 260 MPa with a stress ratio of negative 0.40, and a frequency of 5 Hz. The signal processing technique was based on a channelled spectrum CCD spectrometer. The sensitivity of quasi-static strain measurements was approximately 30 micro-strain with a strain range of approximately negative 1% to 1%. The feasibility of using the EFPI sensor for stiffness-decay measurements during fatigue testing of composites was demonstrated. Preliminary results form the use of a single-mode EFPI sensor design for strain measurements in composites is also presented.