A study on dynamics of mechanical systems including joints with clearance and lubrication

In this work a methodology for the dynamical analysis of mechanical systems considering realistic joint characteristics, namely, joints with clearance and lubrication is presented. For the case of the joints with clearance modelled as a contact pair with dry contact, a technique using a continuous approach for the evaluation of the contact force is applied, in which the energy dissipation in form of hysteresis damping is considered. The friction forces are calculated using a modified Coulomb’s friction law. For the lubricated case, the hydrodynamic theory for dynamically loaded journal–bearings is used to compute the forces generated by lubrication action. The numerical results point out that the existence of dry joint clearances causes high peaks on the kinematic and dynamic system’s characteristics due to contact–impact forces when compared to those obtained with lubricated model. The performance of the lubricated joint is closer to that of an ideal joint.