Preliminary Design Procedure for Insulated Structures Subjected to Transient Heating.

Abstract : A procedure is described for obtaining minimum-mass designs of insulated structural panels loaded by a general set of inplane forces and a time-dependent temperature. Temperature and stress histories in the structure are given by closed-form solutions, and optimization of the insulation and structural thicknesses is performed by nonlinear mathematical programming techniques. Design calculations are described to evaluate the structural, efficiency of eight materials under combined heating and mechanical loads: graphite/ polyimide, graphite/epoxy, boron/aluminum, titanium, aluminum, Rene' 4l, carbon/carbon, and Lockalloy. A study is also performed to assess the effect on design mass of intensity and duration of heating. Results indicate that an optimum structure may have a temperature response well below the recommended allowable temperature for the material. This suggests significant mass savings by lower temperature operation. (MM)