Measurement of the maximum value of non-uniform strain using a temperature-insensitive fibre Bragg grating method

This paper presents an optoelectronic method for measuring the maximum value of non-uniformly distributed strain at varying temperature. Use of conjugate a gradient algorithm and a sensor model makes it possible to determine the maximum non-uniform strain value and the temperature at which the measurement is performed. The described sensor system enables the maximum strain value to be determined with a linear resolution of 0.003 m. A specially designed measurement system is proposed to verify the plausibility of using uniform fibre Bragg gratings for the simultaneous measurement of two quantities. The possibility of using the spectrum of two grating sensors to determine the maximum value of a non-uniform distribution of strain and temperature values is demonstrated.