Comments on “Nonlinear phenomena, bifurcations, and routes to chaos in an asymmetrically supported rotor–stator contact system” by Philip Varney and Itzhak Green [J. Sound Vib. 336 (2015) 207–226]

This study analyzes the obtained equations and results in “Varney and Green (2015) [1]”. The analysis show that: (1) the state-space form of the differential equations in Eq. (16) is apparently incorrect; (2) since all results in the original article are extracted from the equations in state-space form, most of the results are consequently incorrect; (3) most of results shown as the graphs in the article are inconsistent with rotordynamics theory. The correct form of the equations and results are obtained, as well. As concluded in the present study, the equations and figures shown in Varney and Green (2015) [1] yield significantly incorrect behavior for the rotordynamics problem.