Solution-Adaptive Computer Software for Preliminary Structural Design of Hypersonic Vehicles

ResearchSouth, Inc. proposes to develop methodology and preliminary design computer software for the analysis of stiffened composite panels used in designing hot structures on hypersonic vehicles. Phase I of the development will investigate the following major areas of the preliminary design of panel structures which are subjected to severe thermomechanical loading during operation. We will develop algorithms and strategies for determining critical design condition loads from the output of finite element models of the structure. We will investigate at least three approaches: an automated search program which will evaluate output files from finite element models and define critical thermomechanical loading conditions and structural elements from time-consistent load histories: a statistical model which uses the finite element data from large samples and determines the most probable set of design conditions: and a deterministic mathematical model in which a functional is formed using the finite element data base with the design condition combinations being produced by a calculus of variations minimization solution. We will also develop a buckling analysis program which uses conventional analytical methods to define the buckling loads and margins of safety of critical equivalent stiffened panels. We will investigate, demonstrate and deliver adaptive meshing software to improve the resolution of internal loads and the capture of peak moments in stiffened panels and substructure for evaluation of local crippling of the hot structure. Prototype software will be available and delivered at the end of the Phase I effort. Phase II will extend the concepts and software to the operational mode, interfacing with most commercially-available finite element structural packages. Benefits to NASA will include more cost-effective preliminary design programs and more reliable designs.