Low-Speed Aeroelastic Modeling of Very Flexible Slender Wings with Deformable Airfoils

Published versio

Structural Models for Flight Dynamic Analysis of Very Flexible Aircraft

Dissimilar analysis models are considered for the large structural deformations of aircraft with high-aspect-ratio composite wings. The different approaches include displacement-based, strain-based, and intrinsic geometrically-nonlinear beam models. Comparisons are made in terms of numerical efficiency and simplicity for integration of full aircraft flexibility in flight dynamics models. An analysis procedure is proposed based on model substructuring with a (linear) modal representation of both fuselage and tail and (nonlinear) intrinsic beam elements for the flexible wings. Copyright © 2009 by Rafael Palacios and Carlos E. S. Cesnik.Published versio

Computational aeroelasticity framework for analyzing flapping wing micro air vehicles

Published versio

XII-Apologies

A one-dimensional theory of slender structures with heterogeneous anisotropic materials is presented. It expands Cosserats description of beam kinematics by allowing deformation of the beam cross sections. For that purpose, a Ritz approximation is introduced on the cross-sectional warping field, which defines additional elastic degrees of freedom (finitesection modes) in the 1-D model. This results in an extended set of beam dynamic equations that includes direct measures of both the large global displacement and rotations of a certain reference line, and the small local deformations of the cross sections. Two situations of interest are then studied in which this approach provides a simpler alternative to nonlinear shell models: First, we look at the detailed structural response of thin-walled composite beams with distributed loads. In particular, the case of a composite construction with embedded piezoelectric actuators is considered. Second, this methodology is applied to study the low-frequency response characterization of a thin-walled composite beam. Numerical results are presented in both cases, in which a reduced set of finite-section modes allows a full characterization of the actual 3-D structure within a strictly 1-D framework solution.Published versio

Equations of motion of rotating composite beam with a nonconstant rotation speed and an arbitrary preset angle

In the presented paper the equations of motion of a rotating composite Timoshenko beam are derived by utilising the Hamilton principle. The nonclassical effects like material anisotropy, transverse shear and both primary and secondary cross-section warpings are taken into account in the analysis. As an extension of the other papers known to the authors a nonconstant rotating speed and an arbitrary beam’s preset (pitch) angle are considered. It is shown that the resulting general equations of motion are coupled together and form a nonlinear system of PDEs. Two cases of an open and closed box-beam cross-section made of symmetric laminate are analysed in details. It is shown that considering different pitch angles there is a strong effect in coupling of flapwise bending with chordwise bending motions due to a centrifugal force. Moreover, a consequence of terms related to nonconstant rotating speed is presented. Therefore it is shown that both the variable rotating speed and nonzero pitch angle have significant impact on systems dynamics and need to be considered in modelling of rotating beams