Thermo-mechanical response of superalloy honeycomb sandwich panels subjected to non-steady thermal loading

This paper investigates heat-shielding performance and 3D thermal deformation behavior of two superalloy honeycomb-core sandwich panels in time-varying thermal environment by using a self-developed transient aerodynamic heating simulation system and a novel active imaging stereo-digital image correlation (stereo-DIC) technique. To facilitate deformation measurement of large objects using stereo-DIC, a simple but practical technique is adopted for fabricating high-temperature speckle patterns on large measuring areas. The results indicate that the sandwich panels provide good thermal shielding performance under 900 degrees C with the thermal insulation effect stabilizing at around 30%. The measured high-temperature deformation fields of the test sandwich panels reveal that an in-plane homogeneous thermal expansion occurs as expected, while the out-of-plane deformation shows evident axisymmetric distributions with the maximum deflections dependent on the temperature differences between the back and front facets. The results provide a foundational understanding on the thermal-mechanical characteristics of superalloy honeycomb-core sandwich panels, which is essential to the structural design of a superalloy honeycomb sandwich thermal protection system. (C) 2015 Elsevier Ltd. All rights reserved.