Temperature Distribution And Deformation Field Measurement Research Of The Specimen Under Ultra-high Temperature

Along with the harsh service environment of aerospace vehicles,requirements of material performance are also creasing,which brings great challenges to the mechanical properties testing of materials.Therefore,it is great important for the research and application of high-performance materials to seek fast,accurate and low-cost material performance testing methods to solve the problem of material performance testing under ultra-high temperature environment,and obtain accurate material performance parameters.However,the traditional contact measurement has been difficult to meet the requirements of modern high-performance material mechanical properties measurement,which requires the development of a new ultra-temperature non-contact measurement technique.The main research contents are as follows:(1)Aiming at a series of defects such as slow heating rate,high test cost and failure of the test limit temperature to meet the requirements of the material service environment,set of ultra-high temperature mechanical properties test system based on optical imaging technology has been developed.It can achieve multiple loading methods,gas environment and different heating rate by electric heating.(2)Through the analysis and comparison of some common temperature measurement methods,it is found that the method of radiation temperature measurement has great advantages in high temperature measurement,but there are also some problems.therefore,in order to expand the temperature measurement range so that the sample can be tested in a larger temperature range and improve the measurement accuracy,we adopt a non-contact radiation temperature measurement technology combining the two-color temperature thermometer and the industrial CCD camera to achieve real-time and high-precision measurement of the whole surface temperature distribution of the sample.(3)Based on digital image theory and computer vision technology,an image edge detection algorithm and digital image correlation method based on threshold segmentation are proposed for different surface features of the sample,which can track and measure the different surface features of the sample,and extract deformation field in real time.Finally,the effectiveness and reliability of the measurement algorithm is proved by experiments.(4)In this paper,some concepts of linear thermal expansion coefficient of materials are understood,and some main factors that will affect it are analyzed.Under the mechanical properties test system of ultra-high temperature materials,its’ test is carried out by using the proposed deformation measurement algorithm.The influence of heat treatment to the linear thermal expansion coefficient of pure rhenium materials is studied and analyzed.