High-frequency flashing of light source for synchronous measurement of temperature and deformation at elevated temperature

摘要

Synchronous measurement of full-field temperature and deformation at elevated temperature using non-contact optical methods attracts increasing attention in evaluating the high temperature properties of materials. The current optical methods all face one major challenge, which is the strong light reflection on the surface of the specimen. Such strong light reflection could greatly impair the measurement accuracy of the temperature field measured based on the radiation light information. Here, we develop an effective and simple testing system to overcome this difficulty. The measurement system consists of an image and temperature acquisition device, and a light source with the feature of high-frequency flashing and periodic flicking. High-frequency flashing of the light source is driven by a motor and controlled by a field programmable gate array controller. Our system can realize the synchronous control of light flashing, image capturing, and temperature acquisition. Images with light on are used to calculate the deformation field based on the digital image correlation method, and those with light off (without reflection) are used for the calculation of temperature. Based on the continuous change of temperature over time, the temperature field at the moment when light is on can be obtained by interpolating the temperature fields before and after the moment through the fitted curve. Experimental validation on the thermal heating of C/C fiber composites shows a satisfactory result for temperature and deformation measurement.