Double-layer closed ultralow-temperature mechanical test device

The utility model provides a double-layer closed ultralow-temperature mechanical test device, and belongs to the technical field of measurement and test. Comprising a liquid nitrogen tank, liquid nitrogen, a test piece clamp, a bearing ground rail, a pulley combination and fixing support combination, a steel wire rope, a dynamometer, an actuator cylinder, a CCD lens, a lens fixing support, a quartz glass cover, a quartz glass cover plate, double air knives, a nitrogen cylinder, a liquid nitrogen filling bottle, a digital image correlation measurement system and a loading control system. The test piece is horizontally fixed in the liquid nitrogen; one side of the test piece clamp is connected with a dynamometer and an actuator cylinder; airflow of the double air knives flows over the test piece clamp; the quartz glass cover is arranged right above the quartz glass cover plate; the CCD lens is arranged right above the test piece and is connected with the digital image correlation measurement system; and the dig