Efficient Fluid-Structure Interaction Method for Optimization of Micro Air Vehicle Wings

Abstract

Micro Air Vehicle (MAV) wing design has been influenced by biological flyers such as birds and insects due to the natural advantages of flexible wing material aiding in low Reynolds number flight and gust stability. Because flexible membranes deform in the presence of aerodynamic loading, accurate simulation of the flight performance of a flexible membrane wing must involve fluid-structure interaction. Many fluid-structure interaction simulations of micro air vehicle wings have implemented high-fidelity, computationally expensive methods such as coupled computational fluid dynamics and nonlinear finite element analysis. While these methods result in detailed flow field information about a particular wing setup, it is difficult to determine optimum flight conditions such as airspeed and angle of attack for flexible wing applications because of the prohibitive simulation times. This paper introduces a fluid-structure simulation method for evaluating structural characteristics of micro air vehicle wings efficient enough to be used at the conceptual design stage for optimization purposes. The method utilizes an advanced potential flow model to determine the aerodynamic loads and a simplified finite element structural model consisting of shell and shear-deformable frame elements. This particular study focuses only on static flight regimes such as steady, level flight. Contents of the paper include an introduction to both the aerodynamic and structural models, the features of the coupling mechanism between the two models, the framework for the fluid-structure interaction optimization algorithm, and an example wing flexibility optimization performed using this method.