A homogenized plate model for dual-scale analysis of integrated thermal protection system panels

Sandwich structure with corrugated core configuration is amicable for Integrated Thermal Protection System (ITPS) panels of Reusable Launch Vehicles (RLVs), since it can provide sufficient stiffness, strength and thermal insulation. These panels can experience spatial and temporal variation of temperature resulting in vehicle location dependent transient stresses. Thus, spatially optimized design of sandwich structure configuration and properties is desirable, which can be achieved using Finite Element Method (FEM) analysis. However, detailed FEM analysis of ITPS panels along with sandwich structure geometry is computationally intractable due to the vastly different length scales. To address this challenge, a plate model for ITPS panels with properties obtainable from direct homogenization is proposed in this work. The novelty of this work lies in extending the shear and normal deformation plate theories to incorporate location dependent thickness-wise temperature distribution, thus significantly reducing the number of sandwich structure-scale simulations to obtain the homogenized properties. An unit cell approach has also been devised to obtain the sandwich structure-scale stress distribution from the plate-level responses. Simulations with different temperature distributions are performed to elucidate the accuracy of the homogenized First-order Shear and Second-order Normal Deformation Theory (FSSNDT) based plate model to capture both the deflection and local stresses in the sandwich structure.