Uncertainties of Numerical Structural Models in the Frame of Aeroelasticity

P. Reich, A. Reim, M. Haupt, and P. Horst

Abstract. Today, numerical methods for structural and aerodynamic problems are reaching highly versatile and reliable levels. Therefore, the coupling of both do­mains can be solved at a high standard. On the other side, the accuracy of aeroelastic analyses depends on the level of precision with which the stiffness properties and, thus the structural behavior of an aircraft wing structure in means of deformation can be predicted. The presence of uncertainties within the structural model which is in­tegrated in the coupled analysis can affect the fidelity of the structural response and, thus, influence the results of the numeric aerodynamic simulation as well. Invest­igations carried out by the Institute of Aircraft Design and Lightweight Structures (IFL) in the frame of the MUNA-project were focused on two types of uncertainties affecting the accuracy of the static aeroelastic analysis: stochastic uncertainties and uncertainties due to modeling simplifications. Stochastic uncertainties are caused by the deviation of actual structural parameters in realized aircraft wings, like Young’s modulus or wall thicknesses from the original ideal design. This deviations affect the stiffness of the real structure and, thus the structural and aerodynamic response. A method to estimate the sensitivity of the wing structure to random input paramet­ers is presented in the second part. The second class of uncertainties arises from approximations connected to the idealization of the physical and geometric proper­ties of the real structure used in finite element (FE) structural models. In the first part of this work, an overview of modeling effects is given which affect the stiffness properties of the FE structural models and in turn influence the results of static aer- oelastic analysis. The coupled analysis is carried out with a high-order panel method for the aerodynamic domain and a parametric finite element structural model, which allows a wide variation of material and geometric properties of wing box structure. This structural model as well as the aerodynamic method and the coupling routines are presented in the following section.

P. Reich, A. Reim, M. Haupt, and P. Horst

IFL, Hermann-Blenk-Str. 35, D-38108 Braunschweig

e-mail: paul. reich@tu-bs. de

B. Eisfeld et al. (Eds.): Management & Minimisation of Uncert. & Errors, NNFM 122, pp. 157-180. DOI: 10.1007/978-3-642-36185-2_7 © Springer-Verlag Berlin Heidelberg 2013