Optical examination of load transfer in riveted lap joints using portable holographic interferometry

Krishnakumar Shankar; John P. Baird; Robert K. Clark; Hugh M. Williamson

doi:10.1117/12.269809

20 March 1997 Optical examination of load transfer in riveted lap joints using portable holographic interferometry

Krishnakumar Shankar, John P. Baird, Robert K. Clark, Hugh M. Williamson

Proceedings Volume 2921, International Conference on Experimental Mechanics: Advances and Applications; (1997) https://doi.org/10.1117/12.269809
Event: International Conference on Experimental Mechanics: Advances and Applications, 1996, Singapore, Singapore

Abstract

In mechanically fastened single lap joints, such as those employed on aircraft fuselage skin splices, there are two distinct mechanisms of load transfer. At low values of load the transfer occurs primarily through friction between the component sheets while at higher loads the load is transferred by friction as well as through bearing at the fasteners. The load level at which the bearing mode of load transfer comes into action significantly affects the fatigue life of the joint, since the fasteners are stressed only at loads above this threshold load value. The portable holographic interferometry testing system (PHITS) is a robust, portable and sensitive non-destructive inspection system which produces contours of relative out of plane displacement by the method of superposition. PHITS is applied here to monitor the load transfer mechanism and identify the threshold at which the bearing mode comes into effect. In the friction mode there is no relative displacement between the fasteners and the skin panels. In the bearing mode the fasteners are loaded, causing a distinct tipping of the rivets, which is readily observable in the fringe pattern of deflection contours recorded by the holographic system.

Citation Download Citation

Krishnakumar Shankar, John P. Baird, Robert K. Clark, and Hugh M. Williamson "Optical examination of load transfer in riveted lap joints using portable holographic interferometry", Proc. SPIE 2921, International Conference on Experimental Mechanics: Advances and Applications, (20 March 1997); https://doi.org/10.1117/12.269809

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