This is a model of a 1.3m diameter induced draft fan wheel at the foreshore stack at Pasminco Hobart Smelter.

The FEA model was constructed following the discovery of cracks in the fan wheel back plate after only several months of operation. The cracking was caused as a result of flexure of the backing plate at its natural frequency, as shown here in animated form.

Further investigation found that the original drawings had been altered at the manufacturing stage, foreshortening the gussets and causing the problem.

The Finite element method quickly highlighted the failure mechanism, gave confidence for the proposed repair, and consequently, repair under warranty was quickly organised.

To see an animation identifying the high stress areas of this fan, click on the image above....

The finite Element Analysis (FEA) model, shown left, identified the stress and frequency variables which were required as part of the fan design verification.

One of Australia's leading producers of steel will no longer accept a fan supply unless it has been assured by finite element analysis. Their experience of fan failure in the production environment has amply demonstrated the cost effectiveness of this approach.

For more details on this project, click on the image above....

At Norske Skog Boyer operators were experiencing difficulty controlling a vibrating chip feeder. The feeder consisted of a rotating mass suspended on springs below a tray containing wood chips. As the mass went around it would impart a force via the springs to the tray, effectively bumping the chips forward.

Several options were available for modifying the feeder to achieve better control around the operting point. In order to better understand the equipment performance and hence the consequence of modifications, a dynamic FEA analysis was performed. Prior to the FEA the motion of the feeder was mapped using a series of accelerometers.

The FEA analysis was able to determine the natural frequencies of the chip feeder. This corresponded well with the physical measurements taken. The FEA model was able to clearly identify the influence of modifications such as increasing the rotational speed of the mass, reducing the mass etc. In this way it was possible to identify the most effective method for achieving good control without sacrificing production.