IDAC Aids in the Optimised Design of a Flywheel Support Structure

Optimised design of IPP drive support structure for
Piper Test and Measurement, and Siemens.

Background

This case study describes the design and analysis of a support structure for a braking system that was used for a huge flywheel generator. The flywheel generator was designed as a motor generator unit used by the Max-Planck-Institut für Plasmaphysik (IPP) in Garching, Germany, to provide a considerable amount of power for their experiments. IPP is investigating the physical principles underlying a plasma fusion power plant, to produce energy.
Piper Test and Measurement were required to supply a braking system for the flywheel generator. A cantilever supporting structure had to be designed for the braking system, which was to be fixed to the concrete block using some pre-existing holes drilled through the front face of the concrete block. IDAC were required by Piper Test and Measurement to carry out finite element analyses (FEA) to evaluate the design of a support structure for the braking system.

Analysis

The FEA project carried out by IDAC was split into three phases as follows:

Phase 1 – shape

A topological optimisation was carried out in order to determine a preliminary design of the support frame. This part of the project was carried out using the Shape Optimiser in ANSYS Mechanical. The software approximated the initial structure as a large volume, which was then ‘eaten away’ at locations with low stresses, leaving a ‘pixelated’ representation of the optimised support structure. An envelope of the initial volume was defined to locate the soleplates for the support structure and to define the position of the side arms. The loading consisted of a static load (weight of the components and platform) and a dynamic load (reaction torque applied by the dynamometer and disc brake).

Phase 2 – sizing and dimensioning

Using the topologically optimised solution from Phase 1, a design optimisation was carried out in ANSYS Mechanical APDL. A parametric model of beam and shell elements was created and optimised. The design optimisation allowed the design of the support structure to be refined, and the beams and plates to be sized; this was then forwarded to Whittaker Engineering, who would be manufacturing the support structure. Whittaker Engineering made some manufacturing modifications to the supporting structure design and provided IDAC with an Autodesk Inventor model of the structure for further analysis.

Phase 3 – manufactured design

This part of the project involved analysis of the Autodesk Inventor model in ANSYS Mechanical. The solid model of beams and shells was meshed with solid elements and then re-analysed to verify the final design of the support structure.

Design benefit

Carrying out a shape optimisation within ANSYS Mechanical enabled the design of a supporting structure for the 11t brake assembly to be carried out successfully. The analysis provided a design which made use of minimum weight and space, while giving a reliable design and a cost saving. The results from the analyses also showed that maximum performance was attained while avoiding the modes of resonance of the concrete foundation block.

Eddy Perk, managing director of Piper Test and Measurement, says: “IDAC were given a number of criteria which were essential for the successful operation of the system. The thoroughness with which they approached this task was without doubt professional and their capability in applying the ANSYS software impressive. This task would have been both cumbersome and virtually impossible if done without this software. Time and money well spent.”

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