Application Of Fiber Bragg Grating Sensor For Strain Measurement At The Notch Tip Under Cyclic Loading
Behravesh, Seyed Behzad
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Notches are inevitable in many components and structures due to design limitations. In addition, they are the locations for stress concentration and are susceptible to fatigue failure. As a result, the cyclic stress/strain response at a notch is of key importance. Fiber Bragg Grating (FBG) sensors have been successfully utilized for mechanical and thermo-mechanical strain measurement in many cases; nevertheless, their capability of measuring strain at spots with intensive stress/strain has not yet been explored. In this research, FBG sensors are employed for strain measurement at the notch tip. A verification test was designed to substantiate the FBG measurements. The test involves a rectangular magnesium sheet with a center hole, subjected to uniaxial cyclic loading while the strain was measured at the notch tip using three different methods: strain gage, digital image correlation (DIC), and FBG. There were good agreements between the three measurements.