Simulation of Dynamic Instabilities Induced by Sliding Contacts

When dealing with complex mechanical systems that include sliding contact, it is necessary to account for the coupling between the dynamic behavior of the system and the local behavior at the contact. A particular consequence of interaction between system dynamics and contact behavior is the occurring of vibrational instabilities of the mechanical system, induced by the frictional contact. The dynamics of bodies in sliding contact can thus become unstable, due to the modal coupling caused by the normal and frictional components of the contact forces. Friction induced instabilities are at the origin of several everyday issues such as squeaking of door hinges or brake squealing. In literature, a large number of works deal with this kind of instabilities and are mainly focused on applied problems such as brake squeal noise. This paper shows a more general numerical analysis focused on a simple system constituted by a deformable cylinder that rotates around a rigid cylindrical surface with friction. The parametrical complex eigenvalue analysis and the transient numerical simulations show how the friction forces can origin dynamic instabilities due to the coupling between two system modes, even for such a simple system (one deformable body). The simplicity of the system allows for a deeper analysis of contact instabilities. Results from the experimental analysis allow for validating the model and confirm the occurring of the simulated dynamic contact instabilities.