Neumann Engineering


Rock Box FEA Analysis & Re-Design

We re-designed an in-line Rock Box for the Dredging arm of Neumann Group so that it would withstand the loads required over its lifetime. After using Finite Element Analysis (FEA) to confirm that the existing solution was not suitable for the required loads, our engineers delivered a new optimised design including a detailed engineering report and manufacturing package.

The rock box was tasked with withstanding a peak pressure of 500kPa without deforming.

Utilising a surface model, a linear-static FEA was conducted. The FEA concluded that the initial design was not suitable to withstand the peak pressures induced by the dredge. The results are displayed below. All areas displayed as grey can be considered as deformed.

In a bid to optimise the initial design, NES was then tasked with adding supports on the external of the rock box. The second FEA complete was a surface model, non-linear analysis. A non-linear analysis is used to take stress-redistribution into account once a material has deformed. A non-linear analysis does not allow the stress to exceed to yield stress of a material. The results of the non-linear FEA are displayed below.

The results from this FEA verified that the original geometry plus the addition supports were not satisfactory to withstand the induced peak pressures. Therefore, a re-design of the rock box was suggested that was more complementary to standard pressure vessel geometry.

The re-design of the rock box is displayed below.

The geometry of the new rock box utilises curved edges made from lighter grade, cost effective material to withstand peak loading conditions. Additionally, AS4991 compliant lifting points were provided for the rock box lid and skid base. A linear-static finite element analysis was conducted on the new geometry and is displayed below. An engineering assessment of the FEA concluded that the revised geometry was suitable to withstand the specified peak loading conditions. NES supplied a detailed engineering report and a manufacturing package to conclude this project.
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