Faster to reliable rotor bearings - Schffler combines simulation with large-size bearing test rig

2015-11-17 | 000-006-439 DE-EN

SCHAEFFLER AG, PARIS/SCHWEINFURT

Schaeffler at EWEA 2015 in Hall P02-3

Faster to reliable rotor bearings - Schaeffler combines simulation with large-size bearing test rig

The global expansion of wind energy is not slowing down. Stronger systems, more and more versatile system concepts, and tremendously short innovation cycles also demand new solutions for rotor bearings. In order to develop those bearings with the necessary robustness and reliability in the shortest possible time, Schaeffler combines simulation and calculation methods with measurements obtained using the large-size bearing test rig Astraios, which went into operation four years ago. Over the past few years, we have validated the results from the simulation and calculation of wind turbine bearings on the test rig, reports Andreas Mangold, Manager of Strategic Engineering at Schaeffler. As a result, we have been able to significantly reduce the risk of possible failures first occurring in the field.

Data from several years of test rig operation

Schaeffler tests rotor bearings for wind turbines of the multi-megawatt class on the Astraios large-size bearing test rig. These large-size bearings have an outside diameter of up to 3.5 meters. As one of the largest and most state-of-the-art test rigs in the world, Astraios is able to apply the changing load conditions which are created by the wind, weight, and dynamics from real operation to the test bearings - and in a variable speed range. In comprehensive test runs with a variety of concepts for rotor bearings, engineers have obtained extensive data on the behavior of large-size bearings, which sometimes differs significantly from that of small rolling bearings.

Measurements for optimizing the simulation models

The data are used in a variety of ways by Schaeffler. On the one hand, we are able to ensure with the measurements that the newly developed bearing solutions leave the production hall are robust and reliable, explains Mangold. On the other hand, we validate and optimize the simulation models with the data. We test in practice and use the results for the continual further development of our simulation tools. Although the calculations for the operating life of smaller rolling bearings can be applied to large-size bearings, this does not apply for other parameters, such as kinetics or friction torque. Therefore, simulations in these areas must be validated based on test results. The measurements obtained with Astraios are used by the developers of the simulation models to adjust and refine their calculations for the respective bearing types. Based on previous knowledge gathered in this way, engineers at Schaeffler are able to develop new bearing concepts for wind turbines in a very short time and design them optimally for any requirements. Using the verified simulation models, they are also able to validate their results from the currently tested diameter of a large-size bearing to even larger bearings and whole platforms.

Simulation of complete wind turbines

With the new process, Schaeffler is also able to develop integrated solutions for new wind turbine requirements, for example for the use of completely new bearing types. For an application-oriented test, it is important first to define the correct parameters so that the loads and deformations agree with the operating situation in the field. Using the Simpla software for multi-body simulation developed by Schaeffler, the engineers are able to map a complete wind turbine and examine it from the wind field down to the rolling contacts. As a result, they are able to discover the correct parameters for validation on the test rig. The measurements are then incorporated in the simulation models in a multistep process which then calculates the loads and kinematic behavior of a large-size bearing. If, for example, deformations are found, their effects on the function of the rolling bearing can be calculated and validated on the test rig. One practical result from this could be the adjustment in the design or coating of a bearing, but also, as an example, recommendations for lubrication for various operating conditions. This could be a great advantage particularly in off-shore wind turbines, because maintenance work at sea is usually very expensive and complicated.

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