Computation of Bolted Joint Stiffness Using Strain Energy

Abstract

The joint stiffness 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 for interpreting results from finite element models 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. 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. The strain energy method was verified by comparison with previously published results. Results indicate that the strain energy method represents a simple and accurate method for calculating joint stiffness values.