Computation of bolted joint stiffness using strain energy

The joint stiffnesses of preloaded bolted connections were determined using strain energy calculations from finite element models. The strain energy method, proposed here, provides a new, more comprehensive method of interpreting results from a finite element model than methods used previously. Previous works using finite element models have approximated joint stiffness values by computing the average deflections at the bolt-head-to-member interface and dividing this into the applied load in the bolt. Other works have enforced a uniform deflection at the bolt-head-to-member interface, effectively ignoring the coupled stiffness of the bolt head and abutment. Additionally, an assessment was performed of previous research efforts on externally loaded bolted joints. Techniques in modeling, enforcement of boundary conditions, and methods for bolt preload application were assessed. Three-dimensional finite elements were used to model axisymmetric bolted joints. Bolt head geometry was modeled to account for the coupled bending stiffness at the bearing interface.