Comparison of experimental and operational modal analysis on a back to back planetary gear

Abstract

Several modal analyse techniques are widely used to study the dynamic characteristics of a structure by identifying the modal parameters. This paper presents a comparison between an Experimental Modal Analysis (EMA) test, an Operational Modal Analysis (OMA) test and an Order Based Modal Analysis (OBMA) applied on a recirculating energy planetary gear. The OMA and OBMA offer a test of the planetary gear under its real boundary conditions, whereas the EMA is based on the frequency response function estimation. Using these different techniques, the back to back planetary gears modal parameters were identified. In a first step, the experimental results determined by EMA and OMA were correlated to the numerical results model obtained by a three-dimensional lumped parameter model. In a second step, the OBMA estimated modal parameters were compared to those of the EMA. According to the obtained results, OMA cannot excite all the modes. However, it was noticed that there is no significant difference between the modal parameters obtained by the EMA and the OBMA. The natural frequencies and damping ratios were deviating by 11% and 2.43%, respectively.