Structural Design Review of a Tandem Rotary Tippler

LEC has recently completed an independent third-party structural design review of a new tandem rotary tippler and its associated positioner and wheel grippers. The new tippler was procured in order to increase the annual export throughput of an iron ore port.

Finite element model of the tippler and positioner structures

Typical fatigue stress range calculations

Detailed structural modelling and analysis was carried out independently using advanced Finite Element Analysis (FEA). Due to the cyclical motion of the tippler, design checks were focused on the fatigue service life assessment. Stress fluctuation due to the rotating motion of the tippler was calculated by analysing the tippler in several angular operating positions.

The independent design review was predominantly carried out in parallel with the Original Equipment Manufacturer’s (OEM) design process to meet the stringent project schedule. Design anomalies and structural non-conformance with the relevant design codes were promptly communicated to the OEM, thus allowing any required modification to the design to be implemented early in the design phase. This reduces the risk of potential costly production delays due to design issues and the associated on-site remedial work as well as the potential for commercial and/or legal disputes.

LEC also carried out a design review of the vertical lifting arrangement and transport saddles for land and sea transportation of the tippler cage structure, from the OEM’s fabrication yard to the owner’s site.

Design Verification of Drum Conditioner for Lithium Plant

LEC undertook finite element modelling, analyses and design verification of a drum conditioner for a lithium plant in Australia, which included:

• Design code compliance checks in accordance with AS 3990

• Buckling analysis using MSC.Nastran

• Natural frequency analysis using MSC.Nastran

• Fatigue endurance limit calculations in accordance with the requirements of BS 7608

The three-dimensional geometric model was discretised using predominantly MSC Nastran’s QUAD4 plate elements (four-noded quadrilateral isoparametric element) and where necessary TRIA3 (three-noded isoparametric triangular elements). MSC Nastran’s HEXA (eight-noded isoparametric solid elements), PENTA (six-noded isoparametric solid elements) and TETRA (four-noded isoparametric solid elements) were used locally to model the tyre support region closer to the exit end diaphragm to simulate the weld details for fatigue assessment. Fine mesh was adopted in the regions where fatigue assessment was required.

As a result, a design verification report was prepared by LEC containing proposed structural modifications for compliance with the applicable codes and standards.

Weighing of a Stacker Reclaimer

A rail-mounted bucket wheel stacker reclaimer had recently been refurbished following a partial structural failure, but before it could be returned to service it was necessary to weigh the machine to confirm its as-built condition matched the design intent for balance, stability, slew bearing loads and wheel loads.

LEC prepared a weighing method statement and undertook on-site supervision of the weighing, which was undertaken by jacking the eight-wheel bogie structures.

LEC then processed the site measurements to calculate the total weight and weight distribution (centre of mass) of the stacker reclaimer, and compared these to the design values to determine whether re-ballasting might be necessary to ensure the slew bearing service life would not be compromised due to an out-of-balance condition.

Finite Element Analysis of 3500t Sugar Bin

As part of an independent design review, LEC undertook finite element analysis (FEA) and design verification of a 3500-tonne capacity sugar bin.

LEC independently created the finite element model using MSC Patran based on the engineering design drawings of the proposed sugar bin, and the design loads were determined in accordance with the requirements of AS 3774 – Loads on Bulk Solids Containers.

The finite element analyses results were used in the design verification calculations in accordance with the requirements of AS 3990 and AS 4100, and a linear buckling analysis using MSC Nastran was carried out to identify any local member or plate buckling issues present in the proposed bin design.

The FEA results and design verification report were provided by LEC to the client to highlight any components of the sugar bin structure which did not comply with the requirements of the Australian Standards, to enable design modifications to be undertaken prior to fabrication.