Aeroelastic Tailoring using the Spars and Stringers Planform Geometry

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. The aeroelastic performance of a wing, including static aeroelastic shape, flutter/divergence speed and gust load response, has a significant influence on aircraft design. The tailoring of aeroelastic responses therefore offers potential weight savings. In this paper, the spars and stringers planform geometry (i.e. shape and root/tip chord wise location) on a representative wind tunnel model aircraft wing are used to modify the wing aeroelastic performance. Several optimisations are performed to illustrate the ability of the spars and stringers planform geometrical features to change the wing vibrational mode natural frequencies, deformation under a static tip load and aerodynamic load, gust response and aeroelastic instability speed. Changing the stringers planform geometry is shown to offer minor variation in the wing deformation and loads. Changing the spars planform geometry is shown to enable a reduction in root bending moment under static aerodynamic loading greater than 10%, a reduction in maximum root bending moment encounter during a worst case scenario gust event greater than 10% and a 25% increase in flutter speed. The improvements due to a change in the spar planform geometry are compared to the effect of changing the wing sweep angle. A framework to characterise Euler-Bernoulli beam properties on wings with geometric coupling is then developed and validated to relate the stiffness and bend/twist coupling parameter to the full 3D FE models.

Slender-Wing Beam Reduction Method for Gradient-Based Aeroelastic Design Optimization

“…All beam properties, including the second moment of area I 1 , are calculated from the GFEM static deflections due to tip loads as detailed in the next section. Aeroelastic analyses are then performed using the beam model (5), generating aeroelastic constraint values g 1 (6), external loads L (7) and associated gradients with respect to the beam model properties (8). The external loads are applied to the GFEM model for stress analysis (9), which outputs the stress constraint values g 2 (10) and their gradients with respect to the optimization variables ∂g 2 /∂v, and with respect to the applied loads ∂g 2 /∂L (11).…”

“…One application of MDO is the design of aerostructures subject to aerodynamic, stress and aeroelastic constraints. Existing wing MDO implementations, such as those described in [1][2][3][4][5][6], tend to use three-dimensional global finite element models (GFEMs)…”

“…Identification procedures are used to determine beam properties yielding equivalent displacement responses to the full model. This approach was recently implemented in [6], to assess the effects of different spar and rib layouts on Euler-Bernoulli beam bending and torsion parameters. SwiftComp, an implementations of the mechanics of structural genome (MSG) theory developed by Yu [16], also uses this approach for the multi-scale modeling of heterogeneous composite structures, which cannot currently be handled by sectional analysis methods.…”

Corotational Finite Element Formulation for Static Nonlinear Analyses with Enriched Beam Elements

“…The ability of numerical models to accurately predict the flexibility of aerospace structures has therefore become central to further improve aeroelastic performance, e.g. aeroelastic tailoring [1][2][3]. Furthermore, considering the reliance on computer software and the critical choices that must be made during early design phases, the development of accurate, yet rapid, structural analysis methods is of paramount importance for aerospace applications [4].…”

Parametric study of varying ribs orientation and sweep angle of un-tapered wing box model

“…Besides, Jutte et al (2014) have implemented few aeroelastic tailoring methods which also includes the usage of curvilinear rib and spar with varying orientation, tow steering composite laminates and also material and thickness grading on a CRM wing box [18]. Meanwhile, Francios et al (2017) have focused on the modification of spars and stringers planform geometry of a simple rectangular wing box model [19]. All in all, these research works have shown significant effect of curvilinear spars and ribs on the improvement of wing performance.…”