Nonlinear Structural Reduced Order Modeling Methods for Hypersonic Structures

Abstract

This paper focuses on the extension and continued validation of coupled thermal-structural reduced order models for the prediction of the nonlinear geometric response of heated panels of hypersonic aircraft. The large spatial and temporal variations of temperature expected in such structures imply similar variations of the material properties, most notably elastic properties and coefficient of thermal expansion, which must be captured for an accurate response prediction. Accordingly, earlier reduced order models are first extended to include linear variations with local temperature of the elasticity tensor and coefficients of thermal expansion. The validation of these concepts is achieved on a beam structural model. A representative 3-D hypersonic panel is considered next in isothermal conditions to extend the validation of nonlinear reduced order modeling methods to complex structural models. Key in the reduced order model construction is the basis selection and the combination of linear and dual modes introduced and validated in prior efforts is once again found to capture well the structural response, although an additional set of functions, referred to as the tangent duals is introduced to complete the structural response modeling. The corresponding predictions of the forced static and dynamic responses are found to match full Nastran results very well.