Abstract: This paper studies the strengthening and crack-stopping effects of an interference-fit bushing on an attachment lug. A method is presented for treating the boundary conditions of contact surfaces.By use of lugs which is a universal program for stress analysis of attachment lugs, for the first time, a thought that selects a set of optimum parameters of a bushing is suggested.A bushing with optimum performance for a lug with arbitrary size and load case can be designed by using the method presented in this paper.