For all rotational machines, the analysis of dynamic stresses and the resulting vibrations is an important subject. When it comes to helicopters and piston engines, this analysis becomes crucial. From the design of parts working under stress to the reduction of the vibration levels, the success of a project lies mainly in the hands of the dynamicists.

The authors have combined their talents and experience to provide a complete presentation on the issues involved. Part one describes, in concrete terms, the main dynamic phenomena and how they can be observed in reality. Part two presents information about the modeling methods required to understand the dynamic phenomena and develop solutions capable of eliminating the most serious effects.

This book presents a study of the stability of mechanical systems, i.e. their free response when they are removed from their position of equilibrium after a temporary disturbance. After reviewing the main analytical methods of the dynamical stability of systems, it highlights the fundamental difference in nature between the phenomena of forced resonance vibration of mechanical systems subjected to an imposed excitation and instabilities that characterize their free response. It specifically develops instabilities arising from the rotor-structure coupling, instability of control systems, the self-sustained instabilities associated with the presence of internal damping and instabilities related to the fluid-structure coupling for fixed and rotating structures. For an original approach following the analysis of instability phenomena, the book provides examples of solutions obtained by passive or active methods.