中文摘要：

目的为了得到石墨在高温环境下的杨氏模量,为飞行器热防护系统和高温热结构的设计提供可靠的技术保障。方法基于数字图像相关（DIC）方法和通电电阻加热技术,建立一套测量材料在高温环境下力学性能的测试系统。利用该系统,测量高温下石墨试样的表面应变场和应力-应变曲线,计算相应温度下的杨氏模量。在1400℃实验环境下,采用基于DIC与高温引伸计的方法同时测量超高温陶瓷试件的拉伸应变数据,并进行比较验证。结果在1400℃实验环境下,采用基于DIC与高温引伸计方法测得超高温陶瓷的应变-时间曲线吻合良好,方差为1.3×10-7。1200-1900℃高温环境下,石墨的杨氏模量随温度的升高呈线性增长趋势。结论采用基于DIC方法准确有效,该方法可方便快速地实现对石墨材料在高温环境下杨氏模量的测量。另外,该方法也可应用于其他导电材料杨氏模量的测试。

英文摘要：

Objective To obtain the Young＇s modulus of graphite in high-temperature environment, and provide reliable technical guarantee for the design of aircraft thermal protection systems and high-temperature structure. Methods Combining the digital image correlation（DIC） method and energized resistance heating technology, this paper established a test system for measuring mechanical properties in high-temperature environment. Using this system, this paper obtained the surface strain field and stress-strain curve of graphite at different temperatures, and calculated Young＇s modulus of graphite in high-temperature environment. The tensile strain data of Ultra High Temperature Ceramic specimens were measured using DIC and high tempera-ture extensometer method simultaneously at 1400 ℃ in the experimental environment, and comparison and verification were conducted. Results The strain-time curves of UHTC measured by DIC and high-temperature extensometer method at 1400 ℃in the experimental environment were in good agreement, with a variance of 1.3×10-（-7）. In high-temperature environments with temperatures of 1200 - 1900 ℃, the Young＇s modulus of graphite increased linearly with the increase of temperature. Conclusions The method based on DIC was accurate and effective, and this method could easily and quickly achieve the measurement of the Young＇s modulus of graphite material in high-temperature environment. Moreover, the method could also be applied to measure the Young＇s modulus of other conductive materials.