Comparison of analytical and multibody dynamic approaches in the study of a V6 engine piston

M Cavalli, G Lavacchielli, R Tonelli, Gianni Nicoletto, Enrica Riva
  • Proceedings of the Institution of Mechanical Engineers Part K Journal of Multi-body Dynamics, April 2017, SAGE Publications
  • DOI: 10.1177/1464419317705988

Engine NVH issues: piston slap modelling and sensitivity to piston-pin offset

What is it about?

Piston slap can be a very important NVH issue in internal combustion engines, expecially in high performance ones, as the lateral force transmitted to the cylinder liner can be truly relevant because of the high pressure reached in the combustion chamber. This paper compares an analytical method to assess the lateral force with a much more detailed multibody approach. The latter provides an accurate modelling of the contacting surfaces and piston lateral motion, allowing to clearly identify the piston slap events.

Why is it important?

The main finding of the work is the indentification of piston slap events and their great sensibility to the piston pin offset, the distribution of the pressure on the piston top surface and the radial gap between piston and liner. This gap can be accurately determined through a thermostructural analysis of the portion of the engine block surrounding the cylinder. The correlation between the piston rotation/inclination in the plane of motion (influenced by the previously mentioned factors) and the piston slap occurrences is clearly highlighted.

Perspectives

Matteo Cavalli

Working on the piston slap problem suggested to me the importance of the complementary analyses that are needed to give to the multibody model proper boundary conditions. In particular the CFD analyses to determine the pressure distribution on the piston top surface, as well as the thermostructural analyses that give the radial deformation of the bodies should be well investigated prior to get useful conclusions from the multibody model.

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http://dx.doi.org/10.1177/1464419317705988

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