Abstract:

ESDU 89046 presents the results of over 900 axial load fatigue tests extracted from the literature on low load transfer joints under constant or variable amplitude loading. A low load transfer joint is one in which less than 10 per cent of the axial load is transferred between the members and typically half the joints in an airframe fall in that category, for example a skin-stiffener connection in a wing. Five different types of fastener are included, assembled with a range of fits from clearance to interference and with a variety of interfays. The data allow a choice to be made of the most appropriate system to improve fatigue strength under a given loading. Details of the alloys (7010-T7651, 2014-T651, 2024-T351, 2024-T3 clad or unclad, 7050-T76 or T7651 and 7475-7351) and of the test specimens are included and the influence of the various parameters on fatigue strength is discussed. Included are data for joints manufactured with a corner crack in the fastener hole; these tests were designed to investigate a repair in which the hole is drilled out but insufficiently to eliminate an existing crack.