气动热环境下玻璃窗口热应力试验分析

飞行器在大气层内高速飞行，气动加热会引起飞行器玻璃窗口损坏。为分析玻璃窗口在气动热环境下热应力状态，在高频等离子体风洞中采用电阻应变计测量方法开展了试验研究。本文针对玻璃窗口的特点，介绍了玻璃窗口模型的固定支架设计以及在玻璃上安装应变计的方法和特点。针对试验快速升温的特点，对应变计标定了瞬时热输出，并与稳态热输出进行了对比。通过风洞试验得到了气动热环境下玻璃窗口模型应变应力变化结果，并利用有限元计算验证了该试验结果。试验结果表明，玻璃窗口模型在最高温度300℃试验状态下应力状态处于合理水平，热应力不会对玻璃窗口造成损坏。

Experimental thermal stress analysis of glass window in aerodynamic thermal environment

Severe thermal stress will be generated on the window structure when the vehicle flies fast in the atmosphere because of heated air.The window structure may possibly be damaged or the optical error may be increased by thermal stress,accordingly.It is necessary to analyze thermal stress field of the window structure.Thermal stress of a glass window in aerody-namic thermal environment was analyzed,relative wind tunnel experiment was made to measure its thermal stress.A special brace was designed taking the character of the glass window into consideration.Thermal stress experiment for the glass window model was done in a high-frequency plasma wind tunnel.During the experiment,high temperature strain was measured using the resistance strain gages.The ways and characters of installing strain gages on glass window model were introduced.According to the feature of rapidly increasing temperature during the experiment,transient thermal output and steady thermal output of the strain gages was calibrated and compared.The stress and strain of glass window in aerodynamic thermal environ-ment were obtained,the highest temperature reached up to 300 ℃.The thermal stress analysis of the window model was investigated numerically using a finite element software.The error between the measured values and the computed values of the window model’s thermal stress was about fifteen percent,and the experimental results were identified.The experiment shown that the glass window model was affected by compressed stress.Stress state of the glass window model under the experimental condition is normal and the glass window won’t be damaged by thermal stress.