The Application Of Digital Image Correlation Method On High Temperature Deformation Test Of Thermal Structure Material

As the rapid development of aerospace enterprise in every space powers, newaircraft flight speed faster and faster, then there is the demand for higher thermalprotection system, thus, the high-temperature mechanical properties of thermalstructure material become the design basis of thermal protection system and theaircraft structure.As a kind of non-contact deformation measurement method, Digital imagecorrelation method is emerging in recent years. Compared with the traditionaldeformation measurement methods, it has a wide range of application, strongadaptability to environment, simple operation and the advantage of high accuracyof measurement. Especially in the measurement of high-temperature experiment,the DIC possess unique advantages, it has been widely used in the areas ofexperimental mechanics.In this paper, under the normal temperature environment, using digital imagecorrelation (DIC) and electric resistance strain gauge this two methods at the sametime, conducted deformation measurement experiment, including high strengthgraphite, C/C composites and ultra high temperature ceramic three thermalprotection materials, and obtained the stress-strain curve of three kinds ofmaterials and related mechanical properties. As well as, the digital imagecorrelation comparison have been carried out to verify its feasibility and theaccuracy of measurement. Besides, analyzes the influence of measurement error onthe subdomain size and calibration calculation.In order to get the mechanical properties of the material under test inhigh-temperature environment, under the environment of high temperature testsystem, this paper combined Vic-3D measurement system with high-temperaturemechanics performance test system based on electrical heating to establish a set ofnon-contact deformation measurement. Using this system this paper conducted aseries of high temperature mechanics experimental:1) The DIC method is used for deformation measurement experiment ofhigh-strength graphite in different temperature, obtained the stress strain curve ofhigh-strength graphite at1200℃,1600℃,1800℃and1900℃temperature, andgives its compression modulus of elasticity with temperature changes in therelationship;2) Both the DIC method and extensometer method were used for the C/Ccomposites deformation measurement at high temperature, and got tensile modulusof elasticity of the C/C composites under1400℃temperature; 3) Using DIC and two methods for the extensometer ultra high temperatureceramics at high temperature deformation measurement, the ultra high temperatureceramics at1600℃temperature tensile strength and modulus of elasticity.Finally combined with the influence factors found in the experimental course,such as speckle quality, thermal expansion, the oxidation of the material and lightinterference, the influence of experimental error are analyzed respectively, and thesolutions are put forward.