The application of the dynamic stiffness method for the acoustic fatigue analysis of aircraft engine nacelle structures

The subject of acoustic fatigue first came to prominence with the advent of using jet engines on commercial aircraft in the 1950’s. Despite the period of time which has elapsed since then and the work carried out to help develop our understanding of the response of structures subject to high intensity noise, acoustic fatigue problems still occur. The novel contributions which this thesis makes to knowledge in the area have been in the application of the dynamic stiffness method which has been used to predict stress and strain response due to acoustic loading. The dynamic stiffness method can under certain circumstances provide very accurate results for natural frequency and displacement. Indeed for certain configurations it can provide exact solutions. It is largely independent of the number of degrees of freedom necessary to give an accurate result unlike the finite element method. The thesis documents how the dynamic stiffness method can offer a very favourable alternative to available analysis techniques. An alternative method of formulating the dynamic stiffness method is presented and is further extended to theanalysis of orthotropic plates. The response of actual structures is discussed and previously unpublished data is also presented