On geared rotordynamic systems with oil journal bearings

This study investigates response and stability characteristics of rotordynamic systems interconnected with gear pairs and supported on oil journal bearings. The systems examined are driven by a motor providing a known torque, which is transferred to a load element through shafts and a gear box. Initially, the emphasis is placed on the gear-pair action, by assuming that the interconnecting shafts are rigid. This results in low order mechanical models with strongly non-linear characteristics, whose long-time dynamics are then effectively studied by applying appropriate numerical methodologies. In this way, useful information is obtained about the influence of the loading, the gear mesh and the journal parameters on the system dynamic behaviour, including periodic, quasi-periodic and chaotic response. Efforts are also directed towards predicting the onset of oil whirl instability and investigating its effects on the system dynamics. The focus is then shifted to more realistic models, including the flexibility of the interconnecting shafts. In this case, the order of the system is first reduced by applying a component mode synthesis method, which takes advantage of the fact that the non-linearities are located at the journal bearings and the gear mesh only. As a result, it is possible to study the dynamics of the reduced rotor-bearing model by employing the methodology that was developed for the gear-pair models. (C) 2001 Academic Press.