Bond Graph Model of a Multi-Plate Clutch in a Vehicle System Using Fixed Causality Slip-Stick Friction

摘要

Slip-stick friction is present, to some degree, in all mechanical systems. When sliding surfaces approach zero relative velocity, the surface irregularities become important and the surfaces stick together. In this state, a force larger than the sliding friction force is required to break through the static friction force and allow sliding to resume. When sliding occurs, the friction element prescribes a force, and when the surfaces stick, the friction element prescribes a velocity. Such switching of causality creates problems in a simulation model as different state representations can result from the causal switch. In this paper a fixed causality friction model is developed that is useful for computation when multiple friction surfaces interact. It should be noted that the model developed here has some similarity to the LuGre moded, but is not used to assess micro pre-slip conditions.