Models of friction damping with variable normal load for time-domain analysis of vibrations

New models of friction have been developed for consistent and effective determining the friction forces for time-domain analysis of vibrations of mechanical systems. The models allow arbitrary variation of the normal load, including the case of partial separation of the contacting surfaces, and arbitrary variation of the characteristics of the friction interface (e.g. friction coefficient, contact stiffness, etc.) in time. Relative motion of the contacting surfaces along a line and a general case of the relative motion in a plane of the friction contact interface are examined. Anisotropy and variation of the characteristics of the friction interface as a function of co-ordinates of the contact surface is accounted for. Examples of friction forces modelling and analysis of forced response using the developed models are presented