Application of electronic speckle pattern interferometry in thermal expansion coefficient measurements

The thermal expansion coefficients of LY12 and 45 steel in different temperature-rising ratio are acquired by electronic speckle pattern interferometer (ESPI). For the pictures (300-500 frames) of each experiment, a batch processing code was designed to identify the central lines automatically instead of the old manual recognition. After displacements and real-time temperature measurements obtained, the thermal expansion coefficients can be deduced. It is proved that in the temperature-rising-ratio range concerned in this paper, the thermal expansion coefficients are almost independence on temperature-rising ratio, and at the same time, they increase within a narrow range when the temperature rises.