时变热辐射环境下高温合金蜂窝板三维热变形测量

轻质、高强和隔热性能优良的蜂窝合金板结构已广泛用于航空航天领域,其在模拟瞬态气动热环境下的热变形是高速飞行器热防护结构设计的重要参数之一.首先,用自行研制的红外辐射瞬态气动热实验模拟系统模拟与其服役环境类似的时变热辐射环境,用新型"主动成像"三维数字图像相关(3D-DIC)测量方法对高温合金蜂窝板结构试件在时变热辐射环境下不同时刻的三维热变形进行了测量.其次,为保证三维数字图像相关测量方法能有效实施,提出一种制作稳定的大面积高温散斑新方法,该方法制作的高温散斑能在整个实验过程中保持稳定,可作为高温变形的有效载体.最后,用Hoff等效刚度理论计算高温合金蜂窝板在稳态时的最大翘曲位移.研究结果表明:210 mm×210 mm的高温合金蜂窝板在单侧面辐射加热条件下其面内变形为均匀热变形,而离面变形为轴对称的翘曲变形,在900℃时其最大离面翘曲位移约为1.6 mm;Hoff等效刚度理论计算结果与实验结果相吻合.

3D thermal deformation measurement of superalloy honeycomb panels in time-varying thermal radiation environment

Superalloy honeycomb panels with the advantages of light weight, high strength and excellent heat-shielding properties have been widely used in the field of aeronautics and astronautics. Deformation measurement of superalloy honeycomb panels due to transient thermal loading is essential for the design of heat-shielding structures. Firstly, a self-developed infrared radiation transient aerodynamic heating simulation system was used to simulate conditions similar to transient aerodynamics service conditions and a novel active imaging three-dimensional digital image correlation (3D-DIC) method was used to measure 3D thermal deformation of a superalloy honeycomb panel sample with a size of 210 mm×210 mm at different times in time-varying thermal radiation environment. Secondly, to ensure the reliability of measurement by using 3D-DIC, a new technique for making large-area high-temperature speckle pattern on a test sample was proposed. The high-temperature speckle pattern stayed stable throughout the experiment and could be used as an effective carrier of thermal deformation. Finally, the largest warping displacement was also calculated by Hoff's equivalent stiffness theory. Study results indicate that in-plane thermal expansion is homogeneous when the panel is heated one-side by radiation heating, while the out-plane displacements show evident axisymmetric warp deformation with the largest warping displacement of approximate 1.6 mm at a temperature of 900℃. The experimental results agree well with theoretical predictions made by Hoff's equivalent stiffness theory.