Virtual Displacements, Hamilton’s Principle, and Lagrange’s Equations

One of the most important concepts used in the writing of the aeroelastic equations is the generalized aerodynamic force matrix. This entity contains information on the aerodynamic model. However, its definition is based on energy methods used for structural analysis, such as Lagrange’s equations. This chapter introduces the necessary background to later derive the generalized aerodynamic force matrix. In particular, the following topics are introduced: The reader should be aware that these topics are typically introduced in what is termed structural dynamics. The applied forces are not necessarily aerodynamic forces in the presentation of the material of this chapter. However, this book will only use aerodynamic forces to build an aeroelastic stability problem.