High-temperature deformation measurement of the heated front surface of hypersonic aircraft component at 1200 °C using digital image correlation

The outside surface of a hypersonic aircraft flying in the atmosphere is in an extremely harsh high-temperature environment due to severe aerodynamic heating. It is important and difficult to measure the deformation of the heated front surfaces of aircraft components in high-temperature aerobic environments in transient aerodynamic heating experimental simulation system for high-speed aircraft. In this paper, an experimental system of strain measurement for the heated front surfaces of hypersonic aircraft components was established. The strain distribution of the front surface at temperatures up to 1200 °C in an aerobic environment was successfully obtained in combination with a digital image correlation method. The processing results of speckle images of heated front surfaces of two different materials show that the measurement results for Al₂O₃ ceramics have a high goodness of fit with the “strain-temperature” relationship derived based on Hillman's “thermal expansion coefficient-temperature” relationship. The experimental results of the nickel-based superalloy (1Cr18Ni9Ti) conform well with existing data, which verified the credibility and effectiveness of the proposed experimental method. The optical measurement system developed for measuring strain on the heated front surfaces of components in a 1200 °C high-temperature environment provides an important means for thermal strength analysis as well as for the safety and reliability design of the heated components of hypersonic aircraft.