The ERIKS group, a European market leader for industrial products and services, was required to design and build a safe temporary access platform for a sewage treatment settlement tank, by their client Thames Water. Periodically settlement tanks are drained for engineers to gain access for inspection and/or maintenance works and as such a safe platform was required to enable access. The access platform was constructed from aluminium.
IDAC was approached to carry out a finite element analysis (FEA) to confirm that the structure conformed to the design criteria.
IDAC were required to carry out a linear structural analysis of the access platform and check the safety factors. IDAC created two 3D models of the platform using the AutoDesk Inventor CAD system to represent two configurations of the platform; legs forward and legs back. The geometry was simplified to remove any small features that were deemed unnecessary for the analysis. Contact conditions were set for all the interfaces and fully fixed constraints were used at the supports.
Although the platform was only required to carry one person, area loads were applied at two locations to simulate two people standing on the platform in case of emergency.
The graphics below show the equivalent stress and deflection results for the ‘legs forward’ configuration. The results for both configurations were well within design limits in terms of stress and structure deflections under load were small.
In addition to these results the safety factors were also calculated for the entire structure and the minimum safety factor for both leg configurations was found to be five. This showed that the access platform was well designed for its purpose.
Design benefit
The analyses showed that the factors of safety for both leg configurations, when carrying double the load, were above five throughout the model. This meant that the platform could potentially carry up to five people and still have a safety margin of 100%. The deflections in the structure under normal operating conditions were in the order of 1.5mm, which implies a stiff structure that is unlikely to sway during usage.
Carrying out an FEA simulation has given ERIKS the confidence that their access platform had been well designed in terms of comfort as well as safety even under onerous load conditions. Thanks to IDAC, ERIKS has been able to put its temporary access platform on the market knowing that it will be 100% reliable in terms of structural integrity.