Modelling a quad-bike rollover mechanism when traversing an asymmetric bump

Experimental testing of a quad bike traversing a bump placed in-line with one of the vehicle’s wheel tracks showed that a passive rider could be displaced across the quad-bike seat resulting in the vehicle’s sudden unintentional steering. It was hypothesised that this ‘bump’ mechanism could result in a rollover. To determine whether such a bump mechanism can precipitate a rollover and under what conditions it occurs, an earlier developed quad bike FE model combined with a seated Anthropomorphic Test Device FE model was validated against experimental tests of the quad bike traversing a semi-cylindrical bump. A sensitivity analysis was then carried out varying the initial conditions of ground friction and approach angle on flat terrain. The FE simulations show that the bump mechanism, for a particular set of friction values and approach angle, resulted in a rollover. The identified bump-induced rollover mechanism could help explain some of the rollover-associated quad bike crashes on Australian farms where it was known that a fatality occurred as a result of rollover which happened due to traversing a bump from Coronial investigations carried out by the authors.David Hicks, Mario Mongiardini, Raphael Grzebieta, George Rechnitzer and Keith Simmon