On the fatigue life analysis of monolithic laminated CFRP designs of large aircraft spoilers

The current state-of-the-art commercial aircraft spoiler, such as Airbus A330 is a sandwich design lightweight structure, which consists of a laminated upper and lower skin and a honeycomb core in between. Manufacturing of such designs is costly and therefore an alternative monolithic laminated CFRP spoiler design proposed recently in literature is studied. The current design is proven to operate and carry the loads applied during its entire service life. However, the proposed monolithic design of the spoiler has not been analysed under typical fatigue loading spectrum. Therefore, this contribution aims to demonstrate the application of detailed fatigue life analysis to achieve a well justified monolithic structure. A simplified finite element model representing the design and function of a monolithic spoiler is developed to study the fundamental stress states under static load cases. The commercially available fatigue life analysis software FEMFAT (developed by ECS GmbH) is used to predict the fatigue life of the spoiler based on the computed stress and the results are evaluated according to the current flaw-tolerant safe-life approach. Finally, through-the-thickness stresses, which are particularly present in corners of stifened monolithic panel designs are assessed by means of submodeling.