An evaluation of a novel plastic optical fibre sensor for axial strain and bend measurements

This paper reports the use of a low cost, intensity-based plastic optical fibre sensor for curvature and strain measurement in samples subjected to flexural and tensile loading conditions respectively. This simple and robust sensor exhibits a high signal-to-noise ratio and excellent repeatability, rendering the system cost effective for operation in harsh environments. In addition, this inexpensive system offers a signal linearity and signal stability comparable to that of an in-fibre Bragg grating sensor and other more sophisticated optical fibre sensor systems. Test results have shown that the sensor exhibits a highly linear response to axial strains of up to 1.2% and bending strains up to 0.7% offering a strain resolution of up to 20 microstrain. Findings from a series of cyclic tests have demonstrated that the sensor response is highly repeatable, exhibiting only a very small amount of hysteresis. The results also highlight the possibility of using the sensor for monitoring strain on either the tensile or compressive side/region of a beam subjected to flexural loading.