Thermomechanical performances of sandwich panels with multi-layer multi-row lightening holes: Comparative study on corrugated-core and X-core

In the present study, corrugated-core and X-core sandwich panels with multi-layer and multi-row lightening holes are designed from the perspective of extending the thermal short-circuit path. The thermal insulation performance and load-bearing capacity of the integrated thermal protection structure are investigated and enhanced by sequential thermal–mechanical coupling method. For the corrugated-core sandwich structure, heat proofing effect of schemes altering the quantity of lightening holes along the vertical and lateral directions is relatively similar. Compared to a solid corrugated panel, the maximum temperature of the bottom panel is reduced by up to 86.7 K after arranging the lightening holes. Under the joint effect of temperature load and aerodynamic pressure load, the equivalent stress of double-layer lightening holes at the bolted joints is slightly above the material yield strength. X-panel with three kinds of lightening holes decreases the maximum temperature by 54 K, 60 K and 76 K, respectively, compared to that without lightening holes. Increasing the number of lightening holes along the thickness direction has a noticeable effect on the insulation performance within the safety limits. Special X-shaped structure enhances the structural stability, which has a maximum deformation of merely 0.29 mm. Overall temperature of the X panel is lower than that of the corrugated plate by 39–63 K and has better uniformity of the temperature distribution on the bottom panel. These findings enlighten that passive thermal protection technologies could focus on the direction of setting multiple barriers along the direction of temperature transfer.