Research project: Design concept for oscillating rolling bearings

Research project: Design concept for oscillating rolling bearings 1
Research project: Design concept for oscillating rolling bearings 2

The steadily increasing demand for renewable energies requires constant further development of the respective green and clean generation technologies. For wind power, this represents a major challenge in the area of research and development in a wide variety of subsectors. Specifically for wind power, this means stronger outputs, rising towers and larger rotors, while at the same time taking into account that turbines must run for as long as possible with as little maintenance as possible.

Especially with regard to service life, bearing systems represent a critical sub-element of any wind turbine. Due to ever larger wind turbines, pitch (adjustment of the rotor blades) and yaw bearings (adjustment of the nacelle) are exposed to high loads and are prone to premature damage. Therefore, they have to be designed in such a way that a reasonable lifetime can be guaranteed without unforeseen maintenance and repair services. At the same time, however, economic variables must be taken into account when designing the storage systems in order to be able to offer the end customer an economically competitive product.

Attempts to take the various aspects into account as efficiently as possible when creating the design are on the agenda in the area of research and development. The use of “individual pitch control” strategies, for example, currently represent an efficient technique for reducing the load on the overall system and thus saving materials and resources. However, this further increases the demands on the raceway of the pitch bearings and increases the risk of design-related damage. Specifically, fatigue of these bearings is cited as the cause of bearing damage. This means that cracks form, for example, in the bearing shells and then propagate through the material. Only after a certain time do these grown cracks then lead to a spontaneous failure of the bearing.

The aim of the project is to develop a design concept for oscillating roller bearings that enables a long bearing life while taking into account the conditions of large wind turbines with relatively soft structural components, such as hub and blade root. This design concept is further intended to be a basis for specific future bearing designs. As an essential part of the design concept, a novel calculation concept for estimating the service life of oscillating rolling bearings is planned, which uses the “Finite Element Method” (FEM) to map local stresses in detail, such as the rolling elements on the bearing shell. Based on these local stresses, possible failure modes are defined that determine the bearing’s service life.

The Institute BAB – Project Description BAB 2020, Vers. 10.01.20 Page 4 of 24 for Wind Energy at Bremerhaven University of Applied Sciences, fk-wind:, is planned to set up the necessary measurement stands, carry out the tests and process the measurement data. The institute brings the necessary expertise to carry out measurements on components as well as the detailed knowledge of rolling bearings and pitch drives in wind turbines. In this context, fk-wind: is responsible for the development of a concept for the experimental verification of the assumptions of local damage mechanisms. In addition to the concept development, this includes the set-up of a series of tests to map local load and damage in a rolling bearing, the execution of the tests and the evaluation of the results. Subsequently, a test series for a test bearing will be set up on the basis of the correlation between local load type and failure mode developed by P. E. Concepts.