Friction modeling for dynamic system simulation

Friction is a very complicated phenomenon arising at the contact of surfaces. Experiments indicate a functional dependence upon a large variety of parameters, including sliding speed, acceleration, critical sliding distance, temperature, normal load, humidity, surface preparation, and, of course, material combination. In many engineering applications, the success of models in predicting experimental results remains strongly sensitive to the friction model. Furthermore, a broad cross section of engineering and science disciplines have developed interesting ways of representing friction, with models originating from the fundamental mechanics areas, the system dynamics and controls fields, as well as many others. A fundamental unresolved question in system simulation remains: what is the most appropriate way to include friction in an analytical or numerical model, and what are the implications of friction model choice? This review article draws upon the vast body of literature from many diverse engineering fields and critically examines the use of various friction models under different circumstances. Special focus is given to specific topics: lumped-parameter system models (usually of low order)—use of various types of parameter dependence of friction; continuum system models—continuous interface models and their discretization; self-excited system response—steady-sliding stability, stick/slip, and friction model requirements; and forced system response—stick/slip, partial slip, and friction model requirements. The conclusion from this broad survey is that the system model and friction model are fundamentally coupled, and they cannot be chosen independently. Furthermore, the usefulness of friction model and the success of the system dynamic model rely strongly on each other. Across disciplines, it is clear that multi-scale effects can dominate performance of friction contacts, and as a result more research is needed into computational tools and approaches capable of resolving the diverse length scales present in many practical problems. There are 196 references cited in this review-article.