No abstract

The cryogenic mechanical properties of materials are particularly important in cryogenic engineering fields. The digital image correlation technique is a method to measure strain and displacement with high precision without contact. The optical window is necessary for DIC technology to obtain the cryogenic mechanical properties of materials. However, the thermal radiation energy between the light source, the glass and the sample greatly affects the limit temperature of the cryogenic mechanical measurement. In this paper, the spectral radiation properties of the glass and sample surfaces for the wavelength of 0.38-25 μm were measured. The thermal radiation energy between the power density emitted by the light source, the radiation energy emitted by the glass surface and the radiation energy emitted by the sample were analyzed. Finally, the effects of illumination distances on the radiation energy density and the sample temperature were studied. The results indicate that the power density emitted by the light source accounts for the main part of the radiant energy density received by the sample, and the radiant energy on the glass and the sample surface are negligible. Moreover, increasing the illumination distance is effective to reduce the radiation energy and temperature rise of the sample.