Temperature distribution in a composite box structure subject to transient heat fluxes

Finite element and analytical approaches are used to determine the transient temperature distribution through an air-filled box structure with carbon-fiber-reinforced plastic skins. A study of the individual and combined effects of conduction, convection, and radiation boundary conditions is performed. A novel method for the inclusion of natural convection within a cavity using the finite element program ABAQL'S is presented. It is shown that although the effects of natural convection within the cavity are less significant than that of radiation, they are not negligible and, thus, should not generally be excluded from the analyses. Analytical models based on integral transforms are developed to describe the temperature distribution through the skin, subject to combined thermal loading conditions. Fully transient convection conditions as well as combined semitransient convection-radiation conditions are modeled, and the limits of this analytical solution are explored. The analytical modeling of combined convection and radiation conditions using integral transforms is novel and is shown to predict temperatures within approximately 5°C of those given by finite element analyses.