Simultaneous measurement of two-dimensional temperature and strain fields based on thermographic phosphor and digital image correlation

Abstract

A two-dimensional (2D) phosphorescence-based method is presented for simultaneous measurement of strain and temperature. 6 μm Mg4FGeO6:Mn4+ phosphor particles were sprayed on the surface of the test target for use as a sensor. A measurement system was established, which included a high-speed camera, a 385 nm LED, and a signal generator. The signal generator controls the LED to output a 100 Hz light pulse to excite the phosphor. The phosphorescence is then detected by the high-speed camera with a frequency of 10 kHz. The temperature information is obtained from the phosphorescence decay rate using the lifetime method. A digital image correlation method was then used with the random markings formed by spraying. The 100 Hz temperature and strain measurement technique was implemented based on the current experimental conditions with an accuracy of 2% in temperature measurement and 16% and 9.3% in u- and v-direction respectively in strain measurement. The measurement procedure was used for measurements of temperature and deformation of an aluminum plate with a pulsed current in a temperature range of 0 °C–600 °C and a displacement range of 0–300 μm. The results from experiments show the possibility of 2D measurements of surface temperature and strain in a harsh environment with a non-invasive method.