High Resolution Drilling-Induced Temperature Mapping of CFRP Laminates Using a Fully Distributed Optical Fiber Sensor

In this paper, a method using fully distributed optical fiber sensing is proposed for measuring the temperature profile induced during drilling in carbon fiber reinforced polymers (CFRP) laminates. By loosely inserting the sensing optical fiber into some array capillaries, the strain-free temperature distribution around the bored hole has been investigated experimentally while drilling CFRP plates. A full two-dimensional (2D) map of the dynamic temperature evolution is reconstructed continuously from the data acquired using optical frequency-domain reflectometry (OFDR). The developed OFDR sensor offers the possibility of distributed sensing with a spatial resolution of 2.61 mm. The data of the high spatial resolution distributed optical fiber sensor can be mapped to the temperature distribution in the vicinity of bored hole by two-dimensional reconstruction, similar to meshing a workpiece by using a finite element method. Therefore, 2D temperature distribution over the CFRP has been easily observed. Using an acquisition rate of 100 Hz, the time evolution of the 2D temperature map is captured with high precision, allowing us to analyze the impact of the carbon fiber and drilling directions on the temperature distribution. The method provides a reliable tool to study thermal damage of CFRP components and the dissipation of cutting heat while drilling.