CLIENT NEWS
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GORO NICKEL PROJECT
Many fascinating projects are being modelled using Strand7 worldwide including several major structures for the Athens and Beijing Olympics and the new Wembley Stadium. Of interest to South African users would be the Goro Nickel Project.
In 2002, Outokumpu, the largest provider of mineral processing technology in Australia, were awarded a contract for 9 paste thickeners for the Goro Nickel Project in New Caledonia. These thickeners are 20m in diameter with a 10m sidewall above a conical floor section that makes the tanks almost 20m tall.
All structural aspects of the thickener were modelled using Strand7 including the high torque rake drive unit, the drive shaft, raking mechanism, the bridge structure, and tank and support structure. The drive shaft and raking mechanism model was created in AutoCAD Inventor as a solid model and imported into Strand7 where it was automeshed with plate elements. Beam elements were also used for much of the 3D framework and stiffeners.
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This mesh construction method was perfectly suited to the geometry as it had numerous pipe-to-pipe intersections at different angles, which would have been particularly difficult to model manually. Making changes to pipe sizes and orientations was extremely easy and a great deal of time was saved using the automeshing tools.
The tank and support structures were modelled as a complete unit, which allowed for accurate footing loads to be extracted for all load cases.
Crib Point Engineering were contracted by Cummins to design and manufacture the main traction engine support beams for the new VLocity trains which will be operated throughout Victoria, Australia. Crib Point Engineering employed the specialist services of Strand7 Consulting to perform a Finite Element Analysis to investigate the required proof and ultimate loads and also to perform a fatigue evaluation.
The preliminary design configuration was taken from previously designed traction engine beams. For this project, changes were made to several areas, but most significantly to the governing loads, acceptance criteria, engine mass and panhard rod configuration.
The FE model consisted predominantly of Quad4 shell elements. Rigid links and lumped masses were used to model the engine, transmission and drive shafts. Spring/damper elements were used to model the isolation bushes used at six connection points within the drive system. Contact elements were introduced to accurately model contact faces and restrict excessive movement in certain locations under the ultimate loads.
An initial FE assessment was performed. 26 load combinations were considered for the proof loads and a further 26 for the ultimate loads.
These loads considered all of the possible combinations of positive and negative accelerations in the longitudinal, transverse and vertical directions.
Following the initial assessment, areas were identified that required modification and optimisation to meet the design requirements. All of these options considered constructability, code compliance, potential clash with ancillary components and significantly the maximum permissible weight for the entire system.
This iterative process was first completed for the proof loads and subsequently for the ultimate loads. Proof load acceptance was governed by maximum stress criteria whereas the ultimate analysis considered both material and geometric nonlinearities to ensure that gross failure and progressive collapse of the structure did not occur.
Finally, a fatigue assessment was made in accordance with BS7608. Principal stress ranges were determined for the applied fatigue loads. Each structural detail was classified in accordance with the code and a fatigue life calculated based on the summations of the fatigue damage caused at each location under each load case.
The final configuration of support beams has resulted in a design that has been optimised for fatigue life and structural performance whilst minimising construction costs, manufacturing time and overall weight of the system. You can obtain more information about this project from Sean Turnbull at Crib Point Engineering. Tel: +61 3 5979 1703 Fax: +61 3 5979 3323.