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American Society for Testing and Materials

Aircraft wings are a compromise that allows the aircraft to fly at a range of flight conditions, but the performance at each condition is sub-optimal. The ability of a wing surface to change its geometry during flight has interested researchers and designers over the years as this reduces the design compromises required. Morphing is the short form for metamorphose; however, there is neither an exact definition nor an agreement between the researchers about the type or the extent of the geometrical changes necessary to qualify an aircraft for the title ‘shape morphing.’ Geometrical parameters that can be affected by morphing solutions can be categorized into: planform alteration (span, sweep, and chord), out-of-plane transformation (twist, dihedral/gull, and span-wise bending), and airfoil adjustment (camber and thickness). Changing the wing shape or geometry is not new. Historically, morphing solutions always led to penalties in terms of cost, complexity, or weight, although in certain circumstances, thes...

A Review of Morphing Aircraft

This paper presents a state-of-the-art review on a hot topic in the literature, i.e., vibration based energy harvesting techniques, including theory, modelling methods and the realizations of the piezoelectric, electromagnetic and electrostatic approaches. To minimize the requirement of external power source and maintenance for electric devices such as wireless sensor networks, the energy harvesting technique based on vibrations has been a dynamic field of studying interest over past years. One important limitation of existing energy harvesting techniques is that the power output performance is seriously subject to the resonant frequencies of ambient vibrations, which are often random and broadband. To solve this problem, researchers have concentrated on developing efficient energy harvesters by adopting new materials and optimising the harvesting devices. Particularly, among these approaches, different types of energy harvesters have been designed with consideration of nonlinear characteristics so that the frequency bandwidth for effective energy harvesting of energy harvesters can be broadened. This paper reviews three main and important vibration-to-electricity conversion mechanisms, their design theory or methods and potential applications in the literature. As one of important factors to estimate the power output performance, the energy conversion efficiency of different conversion mechanisms is also summarised. Finally, the challenging issues based on the existing methods and future requirement of energy harvesting are discussed.

A comprehensive review on vibration energy harvesting: Modelling and realization

http://jafari3000.persiangig.com/document/Article(11-20)/1-s2.0-S0263822310001947-main.pdf

Optimum stacking sequence design of composite materials Part II: Variable stiffness design

Mechanical design and multifunctional applications of chiral mechanical metamaterials: A review

A review of modelling and analysis of morphing wings

Aeroelastic optimization of an aerobatic aircraft wing structure

Exact dynamic stiffness matrix of a bending-torsion coupled beam including warping

Aeroelastic dynamic response and control of an airfoil section with control surface nonlinearities

P REVIOUS research showed that elastic coupling and warping restraint might have a positive effect on aeroelastic stability of forward-swept composite wings [1–4]. The work encouraged subsequent investigation into the optimization of composite wing structures for desirable aeroelastic behavior [5–8]. The research has demonstrated that a significant increase of flutter speed can be achieved by optimizing the wing skin thickness or the laminate layups considering the effect of bending–torsion coupling [7,8]. However, the impact of wing geometry upon the influence of stiffness coupling on the aeroelastic optimization has received little attention. This current research is therefore aimed at investigating the effect of swept angle, taper ratio, andmass distribution on aeroelastic tailoring of a composite wing. Six aeroelastic tailoring cases of a composite wing by optimizing the wing box laminate layups have been considered. A classical gradient-based deterministic GD optimization method and a genetic algorithm GA have been employed for comparison purposes. It was noted that the optimized layup solution by using the GD method largely depends on the setting of initial design variables. Nevertheless, this method is efficient and normally produces an optimal result at each step of the optimization process before converging to the final optimal solution. Comparing with the GD method, the GA approach is more robust and produces optimal solutions with little influence from the initial layup despite the need for much more computational time. The example considered in this paper has shown that optimized layups resulting in a maximum increase of flutter speed can be achieved by employing either the GD or GA method. However, wing geometry and mass distribution have significant influence on aeroelastic tailoring results.

Shijun Guo

Papers

A review of modelling and analysis of morphing wings

Aeroelastic optimization of an aerobatic aircraft wing structure

Exact dynamic stiffness matrix of a bending-torsion coupled beam including warping

Aeroelastic dynamic response and control of an airfoil section with control surface nonlinearities

Aeroelastic tailoring of composite wing structures by laminate layup optimization