Computation of member stiffness in the design of bolted joints

In designing bolted connections in machinery applications, it is necessary to estimate the stiffness of the clamped members. The method of Wileman et al. (Wileman, J., Choudhury,, M., and Green, 1., 1991, ASME J. of Mech. Des., 113, pp. 432-437) has become a standard approach to estimating the member stiffness. In this method, finite element studies are used to estimate the stiffness of the clamped members of a single material type. In this paper the studies performed by Wileman et al. (Wileman, J., Choudhury, M., and Green, L, 1991, ASME J. of Mech. Des., 113, pp. 432-437) are extended to include the case where the clamped members are of different material types. Results for a steel/aluminum joint are presented in detail, and a generalized technique for estimating the member stiffness for any material combination is derived. The method developed in this brief is shown to provide accurate estimates of member stiffness over a range of aspect ratios and joint compositions.