Dynamic model of a cylindrical roller on a rough surface, with applications to wind turbine gearbox planetary bearings

Wind turbines of larger power ratings have become increasingly prevalent in recent years, improving the viability of wind energy as a sustainable energy source. However, these large wind turbines have been subjected to higher rates of failure of the wind turbine gearbox, resulting in larger downtime of operation and an increase in cost due to repairs. These failures most frequently initiate in the gearbox’s bearings, especially in the planetary bearings of the planetary stage and high-speed bearings. Currently, most of the research on the detection of planetary bearing faults only addresses the case of localised faults in the outer bearing race, while fewer research considering the detection of distributed bearing faults. The research that does consider distributed bearing faults relies on techniques – such as machine learning for the identification of faulty bearings – that do not account much for the underlying physics of the bearing. In this paper, a model is developed to simulate and analyse the dynamic interaction of a planetary bearing in the presence of surface roughness, which can be used to represent a distributed fault. The model presented uses random vibration theory for simulating the response of the planet bearing induced by distributed faults. The input of the model considers statistical expressions of the roughness geometry using multiple parallel tracks. Numerical simulation of the random vibration of the model is performed using 16 tracks, and the power spectral density of the radial deflection of the roller and the roller–race contact force is determined. The results of the simulation with the multi-track model show that a single-track model significantly overestimates the power spectral densities, and also suggests the stiffness of the bearing race is too high to have an effect on the roller dynamics for a planet bearing.

Experimental Analysis about Heat Treatment Distortion in Bearing Race

It’s well known that the vehicle fuel economy is improved by reducing the weight of their structural and mechanical components. Therefore, there is a demand of bearing race with thin thickness for weight reduction. But, this thickness reduction also causes a large oval distortion in bearings after Heat Treatment (HT). The factors affecting the HT distortion are extremely complicated, which makes it difficult to do rectification only by experimental analysis. There is also a limitation in numerical analysis due to the lack of workable model for HT distortion. Therefore, the aim of this study is to identify the effective factors of HT distortion by experimental approach in order to build suitable numerical simulation model that can estimate HT distortion. The material used in this study is a conventional case-hardened steel (Fe-0.4mass%C-Cr-Mn). The ring with the diameter of 100mm is heat treated and quenched. The resulting HT distortion is evaluated by measurement of maximum and minimum diameter of the race. A jig was developed to correct the ring shape during heat treatment, which helped in identifying that the quenching affects more than 50% of HT distortion. From these results, we developed a cooling equipment to reproduce inhomogeneous cooling rate by controlling oil flow toward the exterior of the ring. The quenching with this equipment reveals that inhomogeneous flow with opposite side (0 degree and 180 degree) reproduces a large oval distortion. The data obtained from the experimental analysis is suitable for developing the numerical model for HT distortion.

ПАРАМЕТРИЧНІ КОЛИВАННЯ РОТОРУ ТУРБОНАСОСНОГО АГРЕГАТУ НА ШАРИКОПІДШИПНИКАХ

This work is dedicated to the problem of ball bearings capacity on the turbopump assembly rotor. Many publications and books have been devoted to solve this problem. The result of research is benefit for designers, technologists and operatives. However, many important questions, which are concerning of ball bearings work, in engineering practice are not sufficiently disclosed. In favor of this is telling the statistic of development of high-speed rotor assemblies. In the total mass of turbopump assembly defects, which appear at the phase of developmental design, more the half of them are belong to the friction nodes, which are including the ball bearings too. The authors are present their own results of the experimental data, which were accumulated as result of the ball bearings tests on the special installation and as part of the turbopump assembly from a Liquid-Propellant Rocket Engine. The defects of ball bearings parts were described and analyzed. The main factors which are worsening the service life of ball bearings in consisting of the turbopump assembly were examined. The kinematics and force interaction of balls with bearing race were examined.In the final analysis was advanced the version of the cause of increased wear of ball bearings high-speed rotor, which consists of the assumption on that during the operation of the bearing, in the radial clearance mode, axial displacements of the balls occur, under the influence of the axial force generated by the flow of the cooling liquid. Also this article shows how these movements of the balls affect the load distribution between the bearing parts and their deterioration.It is assumed that in this mode of operation, in the system "rotor - ball bearing - body" may arise forced axial oscillations. These oscillations are suitable for the term perametric ocillations, since the energy is introduced to the oscillatory system by the periodically changing parameters of the system. In this case, this is the movement of balls, which is expended the energy of rotor rotation or the energy of the flow of cooling liquid.In support of the advanced version, the experimental data on the state of bearings №207Ю and №205Ю were given after the tests with different values of the flow of cooling liquid.

Failure Observation of 3D-Printed Thrust Bearing Specimens at Cross Section Observations in Dry Conditions

3D printing methods are developing and they have become popular recently. 3D printing can easily make complex and seamless parts, however, there are questions about their strength. In particular, the strength of the places where the lamination layer joins is important. We performed rolling contact fatigue (RCF) tests in dry conditions using 3D-printed bearing race and observed the fracture behavior and cracks. We found that the main crack is related to the stress moving direction.

Measurement of Forming Stresses in Plain Spherical Bearings Using Neutron Diffraction

Nosing is a cold metal-forming process used in the manufacture of plain spherical bearings. This process ensures the outer bearing race conforms to the shape of the inner race (a ball), with a composite liner in-between to provide a low frictional moment. These bearings must be precision engineered due to the large forces and demanding environments they operate within in service. The manufacture of these bearings and related process settings is very much an experiential route, although increasingly Finite Element simulations are used to predict and characterise complex material behaviour. It is imperative the numerical nosing models are validated against experimental measurements due to uncertainties in material properties, process variables and part manufacture variations. In this paper, neutron diffraction is used to determine the residual stresses in a large nosed bearing. Measurements were made on the POLDI instrument at PSI, Switzerland. This paper compares the predicted stresses with measurement results, and draws conclusions concerning the validity and usability of the models.