AEROELASTIC BEHAVIOR OF COMPOSITE WINGS IN POSTBUCKLING REGIME

摘要

The use of composite materials in aircraftmanufacturing is increasing due to theadvantages they offer in terms of high strengthand low weight. In addition, if the compositeparts are designed to work in the postbucklingregime, the weight savings and the loadcarrying capacity can be increased. Typicalstructures that can take advantage of this typeof design are stringer-stiffened panels used inwings and fuselages. In the postbucklingregime, these structures show changes in thestress distribution and also reduction of stiffnessdue to geometric nonlinear effects. These effectsmay change the dynamic characteristics of thestructure, such as the natural frequencies andmode shapes, which may consequently causechanges in the aeroelastic behavior of thestructure. Several studies have been made toinvestigate the influence of geometric nonlineareffects on the flutter speed of composite panelsand high-aspect ratio wings, showing that theseeffects can have significant influence on theflutter speed and dynamic aeroelastic response.In this paper, a study of the aeroelastic behaviorof a composite wing structure designed to workin the postbuckling regime is presented. A set offlight conditions including symmetricmaneuvers are considered to obtain the designloads. A sizing process is developed to set thedimensions of ribs, spars, skin panels andstringers allowing buckling on the skin panels.A finite element model is used to model the wingstructure. The analysis model is generated bythe parametric finite element modeling toolMODGEN. Based on a set of input parameters,an aeroelastic model composed of structuraland aerodynamic models are automatically generated. The MSC-NASTRAN solver is usedto simulate the response of the structureconsidering the geometric nonlinearitiesnecessary to model the behavior in thepostbuckling regime, and also to calculate thesteady and unsteady aerodynamic loads by theDoublet-Lattice Method.