Investigation of surface engineering and monitoring for reliable wind turbine gearboxes

• Main Author: Zhou, Jun
• Published: University of Birmingham 2017
• Subjects: 669; TJ Mechanical engineering and machinery
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.731866

Most industrial wind turbines use gearboxes to increase the speed of rotor to the speed required by the generator. However, gearbox is among the least reliable wind turbine subsystems. In this study, the root failure cause of gearbox components retrieved from the field has been analysed and deduced to be the result of the combined effects of misalignment, coarse non-metallic inclusions, and inadequate or inconsistent lubrication, which has been verified using Finite Element Analysis (FEA) simulations. Subsequently, duplex surface systems were designed as WC/a-C:H coating deposited on surface hardened steel to mitigate or eliminate the life-limiting problems of gearboxes, which exhibited superior properties and performance than single coating systems and carburised samples. In addition to the advanced surface systems, an improved methodology of condition monitoring has been developed to avoid unpredictable gearbox failures. Four wheels made of as-received EN36 and EN40BT steel grades, carburised EN36 and nitrided EN40BT were tested against WC wheel using a rolling-sliding wear tester. The development of wheel damage was found to be closely interrelated with the AE signals. The vibration spectrum significantly changed after severe and visible damage formed on the surface of the tested wheel samples.