Effect of stitch on thermodynamic properties of sandwiched thermal protection structures

The thermodynamic behavior of stitched thermal protection structures is simulated using the finite-element method. The effects of stitching step on the thermal protection capability and the induced thermal stress in the stitched sandwich structures are numerically analyzed by ABAQUS codes. The stitched sandwich specimens consist of three components: the upper and lower skins, the heat insulation core and the stitches, and it modeled as a discrete stitched three-layer structure. The structure is subjected to reentry heating corresponding to the Access to Space Vehicle. Two numerical models, for the in-depth heat transfer and for the thermoelastic deformation, are coupled to yield the transient response of the stitched sandwich structures. A heating temperature of 1273 K with constant temperature, isothermal and periodic mechanical boundary conditions are considered. The transient temperature distribution and resultant thermal stresses are then computed. Five different stitching steps are considered and the results of simulations showed that: The ability of stitches in the stitched sandwich structures to improve heat conductivity is limited; however, it has significant influence on thermal stress in the stitched sandwich structures.