| The deformation,damage and failure of materials under high pressure or high strain rate are important research contents of material impact dynamics,which are closely related to the fields of safety protection,material science,manufacturing,national defense science and technology,aerospace science and technology,and the temperature rise is one of the important research parameters in dynamic process.According to the basic theory of geometrical optics and infrared optics,infrared optical systems were designed,and the infrared detector was calibrated by using relevant technique.Finally,the work-heat conversion of 7075-T651 aluminum alloy under the dynamic compression was studied by using the spilt Hopkinson pressure bar system and the single point high speed infrared temperature measurement which was built.The main contents of this paper are as follows.?1?According to the demands in acquiring temperature signal in dynamic loading process and according to the basic principle of infrared radiation and the response of photoelectric effect,the photovoltaic Mercury cadmium telluride infrared detector was selected,which wavelength sensitive range was 2?m12?m,response time was 0.5?s,size was 1mm×1mm;?2?According to the basic theory of geometric optics,two infrared optical systems were designed,namely parabolic mirror system and double Schwarzschild optical system.Zemax was used to simulate and evaluate the image quality and energy transfer efficiency.The results showed that the overall performance of the double Schwarzschild system was better for the arrayed infrared detector system than parabolic mirror system,but the parabolic mirror system had a simple structure so that the installation was easier,so both the two system had their own advantages and application places.?3?According to the principle of calibration,the tube furnace calibration method and thermocouple calibration method were designed.The performance of the two methods was tested by setting parallel experiments.It was found that thermocouple method had better performance in terms of system reliability and data readout efficiency.?4?In order to test the performance of the system,and explore the law of plastic work-heat conversion during the dynamic compression process of 7075-T651 aluminum alloy.In this paper,SHPB dynamic compression tests under four strain rate groups were carried out.The stress and strain data and the corresponding temperature data were used to analyze the relationship between the coefficient of plastic work converted to heat with the strain rate and strain.The results showed that the coefficient of plastic work converted to heat of 7075-T651 aluminum alloy was closely related to the strain and strain rate,which was not a constant in the range of 0.851.At high strain rates,the change of the internal structure make material lose the ability to be further changed,and almost all plastic work was converted into heat.At the same time,it is verified that the high-speed infrared temperature measurement system built in this paper is suitable for dynamic impact test.?5?The uncertainty of the system were evaluated by using the uncertainty theory,and the uncertainty of the system due to random error and system error were analyzed.Finally,the estimated temperature of the 7075-T651 aluminum alloy at the strain rate of1100s-14200s-1 were 35.4?,48.5?,65.9?,92.2?.The values of uncertainty were4.40?,5.07?,6.13?,6.73?,and the degrees of freedom were 4. |
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