Mechanisms of dissipation in frictional joints-Influence of sharp contact edges and plastic deformation

In the present study frictional and plastic dissipation in joints are investigated by means of the finite element method. The Coulomb friction model is used in simulations and the results are compared to experimental measurements. Some of the contacts considered contain numerous internal sharp edges that are localized inside the overall contact region. For joints with sharp contact edges an elastic material model with Coulomb friction is inappropriate because of the sliding-over-edge that occurs in such joints. Here, the sliding-over-edge phenomenon is studied with an elastic-plastic material model in some detail. The phenomenon involves very high plastic strains locally, material build-up in front of the edge and large plastic dissipation. A summation technique for the total dissipation in joints is presented, where each local sliding-over-edge contribution is taken into account. The results are compared to experiments. It is shown that plastic deformation is an important contributing factor to the total dissipation in joints with highly non-conformal surfaces.