SINGLE FILAMENT EMBEDDED IN RESIN MATRIX BY USING A FIBER-OPTIC STRAIN RATE SENSOR

摘要

The authors have developed a new fiber-optic strain rate sensor based on Doppler effect in flexible and expandable light-waveguide (DEFEW). The DEFEW sensor has very wide frequency range from 0.1 Hz to 3 MHz and extremely high strain resolution. It can measure the strain rate change during the high speed phenomena. The sensor has been applied to measurement of micro failure process of single filament embedded in resin matrix. Elastic waves related to fiber breakage and interfacial failure between fiber and matrix were clearly detected. Wavelet analysis shows the two major components with different frequency ranges. Short time FFT is also applied to understand the failure process of fibers. Waveforms and frequency spectrums depend on the fiber rigidity and interfacial property between fiber and matrix.