Operational modal analysis using order-based analysis in a two-stage planetary gear with mechanical power recirculation

Modal analysis techniques are considered as the most used of techniques allowing the characterization of the dynamic behaviour in systems such as planetary gear transmission. During operational conditions, the modal behaviour can be altered. The main purpose of this paper is to estimate the Modal Properties (MP) of two-stage planetary gear during non-stationary regimes using a further version of Operational Modal Analysis (OMA). The natural frequencies and modal damping are determined by Order Tracking (OT) and processed using diagram stability tool. Moreover, the modelling and the treatment of the non-stationary regimes were established. The proposed technique proves that order-based OMA can extract resonances which are related to the interaction between structural modes and the rotational speed harmonics. The experimental measurements are compared to the obtained results via a numerical model. It proves that the natural frequencies and modal damping are significantly dependent on the load.