aeroelasticity

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aeroelasticity

[‚e·rō·i‚las′tis·əd·ē]
(mechanics)
The deformation of structurally elastic bodies in response to aerodynamic loads.

Aeroelasticity

The branch of applied mechanics which deals with the interaction of aerodynamic, inertial, and structural forces. It is important in the design of airplanes, helicopters, missiles, suspension bridges, power lines, tall chimneys, and even stop signs. Variations on the term aeroelasticity have been coined to denote additional significant interactions. Aerothermoelasticity is concerned with effects of aerodynamic heating on aeroelastic behavior in high-speed flight. Aeroservoelasticity deals with the interaction of automatic controls and aeroelastic response and stability. In the field of hydroelasticity, a liquid rather than air generates the fluid forces.

The primary concerns of aeroelasticity include flying qualities (that is, stability and control), flutter, and structural loads arising from maneuvers and atmospheric turbulence. Methods of aeroelastic analysis differ according to the time dependence of the inertial and aerodynamic forces that are involved. For the analysis of flying qualities and maneuvering loads wherein the aerodynamic loads vary relatively slowly, quasi-static methods are applicable, although autopilot interaction could require more general methods. The remaining problems are dynamic, and methods of analysis differ according to whether the time dependence is arbitrary (that is, transient or random) or simply oscillatory in the steady state.

The redistribution of airloads caused by structural deformation will change the lifting effectiveness on the aerodynamic surfaces from that of a rigid vehicle. The simultaneous analysis of the equilibrium and compatibility among the external airloads, the internal structural and inertial loads, and the total flow disturbance, including the disturbance resulting from structural deformation, leads to a determination of the equilibrium aeroelastic state. If the airloads tend to increase the total flow disturbance, the lift effectiveness is increased; if the airloads decrease the total flow disturbance, the effectiveness decreases.

The airloads induced by means of a control-surface deflection also induce an aeroelastic loading of the entire system. Equilibrium is determined as in the analysis of load redistribution. Again, the effectiveness will differ from that of a rigid system, and may increase or decrease depending on the relationship between the net external loading and the deformation.

A self-excited vibration is possible if a disturbance to an aeroelastic system gives rise to unsteady aerodynamic loads such that the ensuing motion can be sustained. At the flutter speed a critical phasing between the motion and the loading permits extraction of an amount of energy from the airstream equal to that dissipated by internal damping during each cycle and thereby sustains a neutrally stable periodic motion. At lower speeds any disturbance will be damped, while at higher speeds, or at least in a range of higher speeds, disturbances will be amplified.

Transient meteorological conditions such as wind shears, vertical drafts, mountain waves, and clear air or storm turbulence impose significant dynamic loads on aircraft. So does buffeting during flight at high angles of attack or at transonic speeds. The response of the aircraft determines the stresses in the structure and the comfort of the occupants. Aeroelastic behavior makes a condition of dynamic overstress possible; in many instances, the amplified stresses can be substantially higher than those that would occur if the structure were much stiffer. See Transonic flight

aeroelasticity

This branch of mechanics is concerned with the mutual interaction between aerodynamic loads and structural deformation. The primary concerns of aeroelasticity include flying qualities (i.e., stability and control, flutter, aileron buzz, and structural loads arising from maneuvers and atmospheric turbulence).
References in periodicals archive ?
Zhao and Yang [24] reported an easy but quite effective way to increase the power extraction efficiency of aeroelastic energy harvesters, by adding a beam stiffener to amplify the electromechanical coupling as shown in Figure 4.
In Section 2, the aeroelastic equations of motion of fluttering panel with von Karman plate theory and both the linear and nonlinear aerodynamic piston theories are formulated.
It may be useful to recall here that the collapse of the Tacoma Narrows Bridge in 1940, one of the greatest disasters in history that occurred on a bridge, was not due to the phenomenon of galloping but to flutter, which has a different aeroelastic origin.
One study focused on aeroelastic tailoring of an Indy car rear spoiler to reduce drag at high speeds and maximize downforce at low speeds [1].
The influence of tower structure parameter before and after optimisation on aeroelastic coupling effect is also analysed.
Raman, "Aeroelastic flutter mechanisms of a flexible disk rotating in an enclosed compressible fluid," Journal of Applied Mechanics, vol.
For example, the linear doublet-lattice method has been frequently used for the aeroelastic analysis of aircraft although CFD techniques offer more accurate numerical simulations.
Karpel, "Design for active flutter suppression and gust alleviation using state-space aeroelastic modelling," Journal of Aircraft, vol.
The main energy harvesting sources in structures are solar, thermal gradient, wind and aeroelastic vibration, and ambient mechanical vibration.
To carry out an efficient aeroelastic analysis, a reduced order model (ROM) based on a finite-state approximation is employed for the evaluation of the matrix collecting the aerodynamic forces [43].
Results revealed the complex nature of the aerodynamic impulses generated by blade-blade interactions, with implications for aeroelastic loads and aeroacoustic sources.
Reliability-based design optimization of aeroelastic structures, Structural and Multidisciplinary Optimization 27(4): 228-242.