Variable inertia effects of an engine including piston friction and a crank or gudgeon pin offset

Research output: Contribution to journalArticle



  • Download full text

    Rights statement: Link to Publisher's website supplied in Alternative Location.

    488 KB, PDF-document



Research units


In order to obtain greater accuracy in simulation, more sophisticated models are often required. When it comes to the torsional vibration of reciprocating mechanisms the effect of inertia variation is very important. It has been shown that the inclusion of this variation increases model accuracy for both single-cylinder and multi-cylinder engine torsional vibration predictions. Recent work by the present authors has revealed that piston-to-cylinder friction may modify an engine's 'apparent' inertia function. Kinematic analysis also shows that the piston side force and the dynamic piston-to-cylinder friction are interdependent. This has implications for engine vibration modelling. Most modern engines employ a gudgeon pin offset, and there is a growing interest in pursuing large crank offsets; hence, the effect of these on inertia variation is also of interest. This paper presents the derivation of the inertia function for a single engine mechanism, including both piston-to-cylinder friction and crank or gudgeon pin offset, and investigates the effect of each through predictions. The effect of crank offset on the variable inertia function is also verified by experiment.
Original languageEnglish
Pages (from-to)397-414
JournalProceedings of the Institution of Mechanical Engineers: Part D: Journal of Automobile Engineering
Issue numberD3
StatePublished - 2008

View connections

ID: 1489252