A review of modelling and analysis of morphing wings

Hierarchical modeling and optimization of camber morphing airfoil

In-plane corrugated cosine honeycomb for 1D morphing skin and its application on variable camber wing

Corrugated structures are flexible in the corrugation direction and stiff in the transverse one. Their bidirectional stiffness properties depend on the special geometries of corrugations. In the paper, a simple analytical model for the initial stiffness of different corrugated composites is developed. The elongation and the effective stiffness in the longitudinal and transverse directions of various corrugated structures (trapezoidal, rectangular, triangular, and quasi-sinusoidal) composites are calculated and compared. Different structural geometries of woven E-glass/epoxy composites are investigated. The validity of the analytical model used is demonstrated by comparing calculation results with experimental data.

https://link.springer.com/content/pdf/10.1007%2Fs11029-014-9401-7.pdf

Corrugated Composite Skins

A simple analytical model for the effective stiffness of rectangular and triangular corrugated composites is developed for the symmetrical and unsymmetrical laminates. The stiffness matrices for the corrugated composites were derived. The elongation and effective stiffness in the longitudinal and transverse directions for the rectangular and triangular corrugated composites were calculated and compared. The dimensions of the rectangular and triangular elements for unidirectional and plain woven fabrics made up of E-glass/Epoxy were investigated. The analytical model has been validated by experimental results from bending and tension tests. FEM models were used to predict the characteristics of rectangular and triangularly corrugated composites using ABAQUS. FEM and analytical models results are compared. Load displacement curves in tensile and bending tests are investigated. Four stages of their mechanical behaviour are identified. Finally ultimate strain and anisotropic behaviour of rectangular and triangular corrugated composites are investigated as experimentally. Results from FEM in ABAQUS, experimental findings, and analytical simulations show that corrugated composites laminates can afford larger deformations than their flat counterparts. Those laminates or skins have significant anisotropic behaviour and they are candidates for morphing applications.

Rectangular and Triangular Corrugated Composite Skins

The method for analyzing the deformation of flexible skin under the air loads was developed based on the panel method and finite element method. The deformation of flexible skin under air pressures and effects of the local deformation on the aerodynamic characteristics were discussed. Numerical results show that the flexible skin on the upper surface of trailing-edge will bubble under the air loads and the bubble has a powerful effect on the aerodynamic pressure near the surface of local deformation. Then the stiffness requirements for flexible skin of variable trailing-edge were given by using the Jacobs rule, i.e., the maximum displacement of skin is not greater than 0.1% of wing chord. Results show that the in-plane stiffness can be reduced by increasing the ratio of bending stiffness to in-plane stiffness. Although the deformation of flexible skin increases with the in-plane stiffness decreasing, it depends on the bending stiffness. When the bending stiffness exceeds critical value, the deformation of flexible skin only depends on the bending stiffness and has nothing to do with the in-plane stiffness. The conclusions can be used for the structural design of flexible skin.

WeiLong Yin

Papers

Stiffness requirement of flexible skin for variable trailing-edge camber wing