Torsional vibration of powertrains:

The recent introduction of stringent emission
requirements together with economic pressure has led
to a particular focus on increasing powertrain
efficiency. This has seen the incorporation of
real-time measurements to predict system behaviour
and engine condition. Accurate models for all
components are thus important. This work investigates
the consequences of some common assumptions made in
low frequency torsional powertrain models, and
proposes improved models where appropriate. In
particular, piston-to-cylinder friction,
(crank/gudgeon) offset, and tyre torsional behaviour
were studied. It was found that piston-to-cylinder
friction can increase the inertia variation of an
engine mechanism. Offset also modifies its nonlinear
behaviour. For small (gudgeon) values these effects
are minimal. However, for large (crank) values, the
effects should not be ignored. The low frequency
torsional damping properties of a small pneumatic
tyre were found to be more accurately represented as
hysteretic rather than viscous. Time Domain
Receptance modelling was used to extend the results
to a multicylinder engine powertrain. The findings
should be of interest to both industry and academia
alike.

Autorentext

Obtained a PhD from the School of Mechanical Engineering at theUniversity of Western Australia (UWA) with this work. He also hasa BE from UWA, has completed a UWA Postgraduate TeachingInternship and been a UWA Whitfeld Fellow. He is currently aresearch associate at DIEM and DEIAgra of Alma Mater Studiorum -the University of Bologna.

Klappentext

The recent introduction of stringent emissionrequirements together with economic pressure has ledto a particular focus on increasing powertrainefficiency. This has seen the incorporation ofreal-time measurements to predict system behaviourand engine condition. Accurate models for allcomponents are thus important. This work investigatesthe consequences of some common assumptions made inlow frequency torsional powertrain models, andproposes improved models where appropriate. Inparticular, piston-to-cylinder friction,(crank/gudgeon) offset, and tyre torsional behaviourwere studied. It was found that piston-to-cylinderfriction can increase the inertia variation of anengine mechanism. Offset also modifies its nonlinearbehaviour. For small (gudgeon) values these effectsare minimal. However, for large (crank) values, theeffects should not be ignored. The low frequencytorsional damping properties of a small pneumatictyre were found to be more accurately represented ashysteretic rather than viscous. Time DomainReceptance modelling was used to extend the resultsto a multicylinder engine powertrain. The findingsshould be of interest to both industry and academiaalike.