Transient responses of a 2-dof torsional system with nonlinear dry friction under a harmonically varying normal load

The effects of a harmonically varying normal load on transient responses of a two-degree-of-freedom torsional system, with nonlinear dry friction and under sinusoidal torque excitation, are reported. An approximate analytical solution for pure slip-type transients is first obtained and confirmed with computational studies. Although the negative slope in friction–velocity characteristics introduces substantial stick-slip motions, a well-tuned normal load could possibly attenuate such motions. Key parameters controlling the engagement rate are identified.