Gear dynamics characterization by using order-based modal analysis

Abstract

The aim of Operational Modal Analysis (OMA) is to estimate the modal parameters of a system in operating conditions. However, for the particular case of rotating machineries during run-up/run-down, it has been demonstrated that the method shows limitations because of the so-called “end-of-order effect”. This is one of the main reasons why new techniques have been explored. The most promising one is Order-Based Modal Analysis (OBMA), which combines advanced Order Tracking techniques with Operational identification methods. To validate this technique, a measurement campaign has been performed on a gear test rig. The test rig has been heavily instrumented to perform the validation of the proposed methodology, combining several triaxial accelerometers on the support plates and gears with state-of-the-art angular position transducers. Firstly, Experimental Modal Analysis (EMA) has been performed to identify a reference dataset. Then, OBMA has been applied on several run-ups/run-downs. The results of modal analysis on orders from different Order Tracking techniques has been compared to those obtained by EMA, confirming that OBMA is capable of correctly evaluating mode shapes and natural frequencies of the gear test rig from operational data.