Simplified tangential force-displacement models for a discrete element particle flow code

We present simplified models of the tangential force-displacement (TFD) behavior of spheres in contact. An improved incremental TFD model is compared with the incremental solution of Mindlin & Deresiewicz [1953] and with the highly simplified incremental TFD model of Walton & Braun [1986]. We show that the proposed TFD model is accurate for varying normal load. Finally, we present results from a numerical experiment using a discrete element method granular how code in which the proposed TFD model has been implemented.