Doing the math to improve ULDs

VRR has been working with DHL for a number of years. So, earlier this year, DHL approached us and explained they were having some problems with their AMX container. This large main deck container, which is compatible with the Boeing 747F and 777F, comes with a shelf that separates cargo into two layers. In DHL’s case, this cargo is express parcels, boxes and euro pallets. Unfortunately, the container’s front arc and pallet edge extrusions were suffering considerable damage during operation.

The advantages of FEM calculations

Not being a company to avoid a challenge, we carried out an extensive inspection of the aircraft, operations and the containers and found several possible causes for the inflicted damage. To research this further, we used FEM calculations and specialised software to calculate the strength and rigidity of the construction and parts of the AMX container. Our engineering department often turns to these calculations to upgrade the design and weight of a container, because they enable the optimisation of aspects such as the material thickness of extrusions, sheets and gussets or the quantity of rivets used.

Finding the cause

Our first task was to find out if the current design of the AMX container, with and without the shelf, was the reason for the damage. The FEM calculations established that the container without the shelf does meet the minimum pallet stress and displacement requirements. However, the container with the shelf falls short of the standard. We had found the cause for the damage.

Improving the AMX container

Our next task was to improve the design of the AMX container with shelf so that it would fully meet all requirements. We did this by finding the most critical position for the Cargo Loading System (CLS) in the aircraft and optimised the design and weight of the AMX container. Resulting in reinforcing the pallet, redesigning the shelf and adding a sliding cover, among other things. The result is a completely new container and base design that is much more suitable for use in a Boeing 747F and 777F, especially if a shelf is required. DHL has already performed some tests and is very happy with the new and improved AMX container.

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