The loadcases were as follows:
Normal usage - a gravitational load was applied to model the self-weight of the structure and forces and moments were applied at the foot of the tow post.
Emergency deceleration - again a gravitational load was applied to model the self- weight of the structure, and a force was applied at the foot of the tow post in order to model the deceleration.
In addition to the above analyses a modal analysis was also carried out for the model in its two restraint conditions. This was required to evaluate the minimum natural frequency of the sway girder. The modal analysis was performed with the corresponding constraints for each restraint condition and a gravitational load to model the self-weight of the structure.
The results requested for each load case were displacements and stresses of the main sway carriage structure and the minimum natural frequency from the modal analysis. The graphics to the right show contour plots of total deformation and equivalent stresses.
It was concluded from the stress analysis of the sway carriage assembly that the current design, subjected to loading and restraint criteria specified by Cussons Technology Ltd, was unlikely to resonate or fail during its operation.