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A collaborative project between four companies has led to the development of simulation software able to calculate the dynamic operating loads acting on wind turbine powertrains. Used in combination with finite element analysis (FEA), the multi-body simulation (MBS) model enables engineers to optimise the design of powertrain components and establish how they interact with other systems.
Technology
Simulating dynamic operating loads is a critical factor in the design of wind turbines. Despite new designs, which have stemmed from new alternative main bearings and gearbox concepts, load simulations have been conducted using relatively simple design calculation models. These models consider only the effects of load over time for specific internal stress variables, independently rather than for all powertrain components, and how they interact. This means that complex units such as gearboxes, which have multiple dynamic components, are treated as a “black box”. The design of the gearbox and how it affects other parts of the powertrain are rarely taken into account.
To gain a better understanding of the dynamic loads acting on the mechanical powertrain components, bearing manufacturer the Schaeffler Group, gearbox supplier Eickhoff Antriebstechnik, wind turbine maker Repower Systems and software company Samtech Iberica have worked together to develop an MBS model. One of the core software applications behind it is Bearinx, a rolling bearing calculation software tool developed by Schaeffler. This software is able to generate dynamic simulation models for complete gearboxes in rapid time. The results can then be visualised.
Bearinx enables users to make bearing calculations, including shaft deflections and stress calculations of complex bearing and gearbox arrangements.
Users can optimise their designs by rapidly seeing the effects of any changes. Various bearing designs and shaft deflections can be considered and compared with FEA calculations.
The partner companies claim that bearing arrangements can be analysed in huge detail, from single bearings through complex shaft or linear guidance systems to entire gearboxes and powertrains. The software can model complete gear systems and simulate the different gearshift conditions of a mechanical or automatic gearbox. Bearinx takes into consideration non-linear elastic deflection behaviour of bearings; the elasticity of shafts and axles; and the influence of fit, temperature and speed on bearing operating clearance, preload and contact angle.
Application
Used in combination with dynamic simulations and FEA calculations for adjacent components and housings, Bearinx enables powertrain simulations to be accurately and reliably modelled. The MBS model allows integrated calculations of fatigue loads or extreme load conditions that may arise during wind turbine operation, including emergency shutdowns or power failures. The partners claim that having a simulation tool available at an early stage in the design process adds to the confidence in the development process. Development costs are significantly reduced as any design modifications can be made much earlier in the design process.