Abstract During flight test programmes structural response data may only be available in terms of accelerations, but relating these accelerations to stresses can be difficult without extensive analysis. Presented here is a method to quickly and accurately generate allowable acceleration levels to prevent fatigue failure. The method applies to lightly damped structures primarily excited at their fundamental mode such as antennae, radomes, and panels, but may be able to be conservatively extended if multiple modes exist. The method relies on the structure primarily responding at its fundamental mode, and therefore that frequency can be used for the upwards crossing rate and also used to govern the relationship between acceleration and displacement. Furthermore, at the fundamental mode the relationship between displacement and detail stress can often be estimated based upon quasi-static considerations. Accurate understanding of the damping in the system is not required. Together these allows simplifications to be made to relate accelerations with stress and then fatigue damage. Accuracy of the results is evaluated and quantified, and the situations where acceptable accuracy achieved is defined. Finally, a nomogram is provided to aid the rapid calculation of allowable acceleration levels.
Rapid Calculation of Safe Acceleration Values for Aircraft Structures Under Flight Test
2019-07-03
17 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch