Introduction to Aircraft Aeroelasticity and Loads

Introduction

Aeroelasticity is the subject that describes the interaction of aerodynamic, inertia and elastic forces for a flexible structure and the phenomena that can result. This field of study is summarized most clearly by the classical Collar aeroelastic triangle (Collar, 1978), seen in Figure 1, which shows how the major disciplines of stability and control, structural dynamics and static aeroelasticity each result from the interaction of two of the three types of force. However, all three forces are required to interact in order for dynamic aeroelastic effects to occur.

Aeroelastic effects have had a major influence upon the design and flight performance of aircraft, even before the first controlled powered flight of the Wright Brothers. Since some aeroelastic phenomena (e.g. flutter and divergence) can lead potentially to structural failure, aircraft structural designs have had to be made heavier (the so-called aeroelastic penalty) in order to ensure that structural integrity has been maintained through suitable changes in the structural stiffness and mass distributions. The first recorded flutter problem to be modelled and solved (Bairstow and Fage, 1916; Lanchester, 1916) was the Handley–Page 0/400 bomber in 1916, shown on the front cover of this book. Excellent histories about the development of aeroelasticity and its influence on aircraft design can be found in Collar (1978), Garrick and Reid (1981) and Flomenhoft (1997), with surveys of more recent applications given ...