Although a great deal of work has been carried out on articulated commercial vehicles, the handling behaviour of coupled cars and caravans has not been investigated to the same extent. The most sophisticated models presented in technical literature disregard important degrees of freedom and often use simplified descriptions of tyre and suspension characteristics. In this paper the equations of motion for a twenty four degree of freedom car and caravan model are developed using Lagrange's equations for quasi-coordinates. These equations are combined with non-linear suspension and tyre characteristics within the simulation environment Bath fp. Caravan dimensional and suspension parameters are measured and used together with data from a fully validated car simulation model to predict high speed instability and handling behaviour. An instrumented car and caravan is tested at a range of speed conditions and good agreement between measurement and prediction is achieved. Following validation, the simulation model can be used to investigate parameters which cannot easily be measured leading to an improved understanding of high speed instability. It is argued that only with a non-linear simulation model which includes the principal car and caravan degrees of freedom can reasonable confidence in the accuracy of prediction be justified. This approach is common place in car dynamics, but to the author's knowledge, has not been used for the prediction of coupled car/caravan pairs.
ASJC Scopus subject areas
- Automotive Engineering
- Safety, Risk, Reliability and Quality
- Mechanical Engineering