Ultrasonic detection method of contact load between rollers and raceways of wind turbine main shaft bearings

Abstract

The load distribution inside a bearing is one of the key factors affecting its operational performance. Abnormal changes in load can lead to premature bearing failure. Therefore, accurately detecting the contact load between the roller and raceway of the cylindrical roller bearings is crucial for ensuring its stable operation and service safety. In this study, an efficient ultrasonic detection method based on the theories of acoustoelasticity and load-induced deformation is proposed for measuring the contact load in roller bearings. First, the intrinsic relationship between the radial deformation of the outer raceway and the ultrasonic Time of Flight (ToF) is established using acoustoelastic theory, and the changes in ultrasonic wave propagation characteristics under load are analyzed. Based on the bearing's force model, the relationship between the deformation and load of the roller bearing is further investigated, and a non-Hertzian contact model suitable for roller contact is developed. By combining ToF variations, an ultrasonic reflection measurement method for bearing contact loads is proposed. Subsequently, a finite element simulation model for single-roller loading is established using a real bearing example, and the reliability of the load-induced deformation theory is verified through simulation. Furthermore, single-roller loading experiments were conducted to measure the ToF of reflected ultrasonic pulses at contact points under different loads. The results showed that the contact load values closely matched the applied load values, with errors within an acceptable range, proving the feasibility of the proposed detection method. Finally, this method was applied to measure the static load distribution of a cylindrical roller bearing, and the results were consistent with the theoretical load distribution, demonstrating the potential of this method for bearing load monitoring applications.