Modeling of Threaded Joints Using Anisotropic Elastic Continua

Using fine material meshes in structural dynamics analysis is often impractical due to time step considerations. Unfortunately, fine meshes are typically required to capture the inherent physics in jointed connections. This is especially true in threaded connections which feature numerous contact interfaces and stress singularities. A systematic method is presented here for representing the threaded volume by a continuous, homogeneous, linear elastic, anisotropic equivalent material. The parameters of that equivalent material depend on thread geometry and the assumed contact condition between adjacent threads and are derived from detailed finite element simulations of a characteristic thread-pair unit cell. Numerical simulations using the equivalent material closely match the local stiffness through the load path calculated from the finely meshed thread models and also reproduce classical theoretical and experimental results from the literature.