Rollover Prediction for Ro-Ro Cargo Trailers

Sammanfattning: ‘High and heavy’ cargo units are carried around the world on roll-on-roll-off (ro-ro) ships. These cargo units are loaded and unloaded using rolltrailers and the risk of rollover for the trailer-cargo unit, during port manoeuvre, often needs to be assessed in short time. On request by Wallenius Marine AB in Stockholm, this thesis examines the dynamics of the rolltrailer and different methods to predict the risk of rollover. The objective is to present a theoretical foundation for a toolbox that can support the assessment of trailer-load combinations. The study focuses on the effect of running over ‘bumps’. An analytic model, based on assumptions of the transfer of energy in the rollover scenario, as well as a simulation, within the SimMechanics environment, was developed and the two were compared. The models produced almost identical output under the circumstances specified. The conclusion was that the assumptions made in the analytic model were reasonable and that the model can be used to characterize the trailer-cargo unit’s stability. The major reservation was that some dynamic properties of the trailer had been neglected and that the model does not account for a sequence of inputs and resonance effects. The recommendation given is to develop the analytic model to an application for practical use. A developed SimMechanics simulation, on the other hand, can be used to examine additional dynamic aspects, resonance effects and other types of influences. Such results could support the decision making regarding what safety margin should be applied to the analytic result.