ESDU Vibration and Acoustic Fatigue Series

To design reliable structures for use in areas of intense sound, engineers need to investigate the possibility of acoustic fatigue failures. Failures during the service life of a structural component may lead to costly design modifications and the introduction of time-consuming inspection procedures. The ESDU Vibration and Acoustic Fatigue Series provides simple and efficient methods for estimating the response and fatigue life of structures typical of those used in the aerospace industry, including fibre-reinforced composites, when subjected to acoustic loading. Although it is not possible to predict precisely the response of a structure under acoustic loading, the structural parameters of various designs can be compared and the design selected to give the best relative performance for a noisy environment. Information is provided on noise from the near-field of turbo-jet engines and from propeller-driven aircraft.

To assess acoustic fatigue life, knowledge of the natural vibration characteristics of the structure is required. The ESDU Vibration and Acoustic Fatigue Series contains data on the natural frequencies of plate, box and shell structures. The plate data cover both conventional metallic construction and laminated composite materials. Damping of the structure is also a factor in the prediction of the fatigue life. Methods are provided for the estimation of damping, including radiation damping.

These vibration data have a wide application in dynamic design calculations where it is necessary to ensure that the natural frequencies of structural components do not coincide with a high-energy region of dynamic excitation.

Normally, acoustic fatigue life estimations are carried out at the lowest natural frequency of the structure under investigation. In cases where the input excitation has a wider frequency range, rainflow and spectral methods are available.