Flutter modeling and simulation of wing section using bondgraph technique

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Date
2005
Authors
Norizham, Abdul Razak
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Abstract
Bondgraph technique. Flutter is the dynamic instability of a structure exposed to airflow. When exposed to airflow, a structure can and will vibrate with its amplitude increasing when there exist any disturbance that creates an oscillation. The vibration will continue until the structure is damaged or destroyed. Interestingly, the vibration with increasing amplitude is only possible beyond a certain speed called critical flutter speed. Beyond this critical speed, the stability of the structure is said to be dynamically unstable. However, below the critical speed, any vibration that occurred will be damped out eventually. The research goal is to predict the vibration response of an airfoil exposed to airflow. The response is obtained using the Bondgraph modeling technique. Bondgraph is used to model the two degrees of freedom flutter system graphically. This Bondgraph representation is coupled with the unsteady aerodynamic filter. The function of this filter is to supply the correct aerodynamic forces with respect to the position of the airfoil in simulation. The simulation is done based on the speed below the critical flutter speed, at the critical flutter speed and above the critical speed. Before any of that can be done, the flutter speed is anticipated first. Then the aerodynamic forces are transformed into the Laplace domain. The transformed forces are used to build the unsteady aerodynamic filter. This filter is then coupled with the Bondgraph representation before being simulated. The result obtained from Bondgraph technique and validation show good correlation with the theory of flutter. Thus Bondgraph can be used to predict the flutter response of wing section. For further improvement, this technique can be applied to model multi degree of freedom flutter.
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Master
Keywords
Aerospace Engineering , Bondgraph Technique
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