Guzzomi A., Stone B.

Complex components may be modelled in various ways. However when a system is made up of many complex components some methods of modelling are very inefficient and their accuracy also becomes questionable. A systems approach has the advantage that each component may be modelled in the most appropriate way and then the models of the components may be assembled to produce a model of the complex system. As an illustration of this approach this paper presents a discussion of the various components involved in powertrain dynamics. Powertrain systems are commonly modelled in the frequency domain and these techniques are well known and accepted. This paper however uses a Time Domain Receptance approach to model torsional vibration. The assumptions currently made in modelling such systems are discussed. Some recent experimental work is described that shows that some major assumptions that are commonly made are not valid. The most significant components are identified and the ways of modelling them described. Components included in the time domain model are the: engine, valvetrain, camshaft drive belt, clutch, continuous shafts, a gear pair and the tyres. Simulations demonstrate the potential of the modelling technique and the ease with which modifications to the model can be achieved. Finally the areas that require further investigation are identified.