Duplex ball bearing outer ring deformation- Simulation and experiments

Abstract

This paper presents a research of deformations influence on duplex ball bearings dynamic behavior. Despite the common use of duplex ball bearings, bearings subcomponents deformations are not thoroughly investigated. In order to investigate these effects, this study integrates the outcome of a 3D dynamic model, developed for assessment of the defect pattern and experimental results from a full scale CH-53 Swashplate test rig. The ability to withstand high radial and bi-directional axial loads makes duplex bearings common in aircraft applications and specifically in helicopter rotors. The swashplate of the CH-53 is constructed of duplex angular contact ball bearings. Two spacers, internal between the static inner rings and external, between the rotating outer rings support the bearing rings. A structural defect is formed by a faulty external spacer, thus causing a lack of support to the top bearing and deformation of the outer rings. Model results indicate that the lack of support has a defect pattern in both radial and axial directions. Test rig data acquired by accelerometers was analyzed by several diagnostic techniques including order tracking, envelope analysis and dephased algorithm in order to recognize the simulated pattern.