Active Control of Rotor Supported by Faulting Journal Bearing

Although hydrodynamic bearings have minimum contact between solid parts, under particular circumstances they might be susceptible to abrasion and wear. In order to mitigate the problem, it is proposed to apply active control methods to reduce the vibration level at critical situations: fluid induced instability and the first bending mode. However, damage in the bearing surface have direct influence over the oil-film pressure and, consequently, in the bearings equivalent coefficients. Although, initially, small variations may lead to minor performance loss, when it becomes more significant close-loop stability may be affected. Therefore, in this paper it is conducted a preliminary study on the effect of journal bearing wear depth effects in active controlled rotors. A structured uncertain model is proposed to include the possible fault coefficients in the model allowing to perform robust stability analysis. Based on the uncertain formulation a robust control solution is designed guaranteeing rotor stability for a certain damage range.