21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-5.3.3

LOAD TRANSFER MECHANISM IN BOLTED DOUBLE LAP JOINTS

Shankar K., Li J.
University of New South Wales, Australia

Keywords: load transfer, bolted double lap joints

In mechanically fastened single and double lap joints there are two distinct mechanisms of load transfer, through friction between the component sheets and through bearing at the fasteners. When a joint with clearance fitted fasteners is subjected to increasing loads, the load transfer initially occurs through pure friction, but subsequently shifts to a combination of friction and bearing at the fasteners. The ratio between the·· component of load transferred by friction and that transferred by bearing has a significant effect on the fatigue life of the joint, since the fasteners are stressed only by the load transferred in the bearing mode. This paper describes the results of an experimental study on aluminium double lap joints with a single bolt attachment investigating the effects of friction and clamping force on the mechanisms of load transfer. Friction between the faying surfaces in the joint is altered by the application of a Water Displacing Corrosion Preventative. Plots of axial load versus axial displacement are obtained for different values of clamping forces on the bolt, for joints with and without the WDCP treatment. The load transfer behaviour observed in the tests agree well with that predicted by a finite element model.

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