Simultaneous measurement of pressure and temperature using single mode optical fibres embedded in a hybrid composite laminated

In this paper, we present a novel smart composite based on single mode optical fibres embedded in a hybrid composite laminated. This smart composite comprehended three optical fibres: an optical fibre positioned between two layers of carbon fibres; other optical fibre embedded in two layers of glass fibres; and another optical fibre inserted between the two different composite laminates. Due to cure process using hot plate press, different optical attenuations were obtained for the three optical fibres. The optical fibre positioned between the two different layers (carbon/glass) presented higher losses when compared with the two other optical fibres embedded between equal types of layers. The losses result from the different diameter of carbon/glass and the different coefficient of thermal expansion of the composite material. The smart composite was characterised in terms of its sensitivity to temperature and pressure, independently. Using a matrix method, it was possible to discriminate the pressure and the temperature with only one measurement. Maximum errors of ±2.45 °C and ±0.6 kN/m2 were found to 60 °C and 2500 kN/m2 measurement ranges.