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Power dissipation in car tyres
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Traffic is a major source of green house gases. The transport field stands for 32 % of the energy consumption and 28 % of the total CO2 emissions, where road transports alone causes 84 % of these figures. The energy consumed by a car traveling at constant speed, is due to engine ineffiency, internal friction, and the energy needed to overcome resisting forces such as aerodynamic drag and rolling resistance.Rolling resistance plays a rather large role when it comes to fuel economy. An improvement in rolling resistance of 10 % can yield fuel consumption improvements ranging from 0.5 to 1.5 % for passenger cars and light trucks and 1.5 to 3 % for heavy trucks.

The objective of this thesis is to estimate the power consumption in the tyres. To do this a car tyre is modeled with waveguide finite elements. A non-linear contact model is used to calculate the contact forces as the tyre is rolling on a rough road. The contact forces combined with the response of the tyre is used to estimate the input power to the tyre structure, which determines a significant part of the rolling resistance. The tyre model accounts for: the curvature, the geometry of the cross-section, the pre-stress due to inflation pressure, the anisotropic material properties and the rigid body properties of the rim. The model is based on design data. The motion of the tyre belt and side wall is described with quadratic anisotropic, deep shell elements that includes pre-stress and the motion of the tread on top of the tyre by quadratic, Lagrange type, homogenous, isotropic two dimensional elements.

To validate the tyre model, mobility measurements and an experimental modal analysis has been made. The model agrees very well with point mobility measurements up to roughly 250 Hz. The eigenfrequency prediction is within five percent for most of the identified modes. The estimated damping is a bit too low especially for the antisymmetric modes. Above 500 Hz there is an error ranging from 1.5 dB up to 3.5 dB for the squared amplitude of the point mobility.

The non proportional damping used in the model is based on an ad hoc curve fitting procedure against measured mobilities.

The contact force predictions, made by the division of applied acoustics, Chalmers University of Technology, are based on a non-linear contact model in which the tyre structure is described by its flexibility matrix. Topographies of the surface are scanned, the tread pattern is accounted for, and then the tyre is ’rolled’ over it. The contact forces are inserted into the tyre model and the response is calculated. The dissipated power is then calculated through the injected power and the power dissipated within each element. Results are promising compared to literature and measurements.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2006. , 17 p.
Series
TRITA-AVE, ISSN 1651-7660 ; 2006:26
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-3994OAI: oai:DiVA.org:kth-3994DiVA: diva2:10299
Presentation
2006-06-13, MWL 74, Teknikringen 8, Teknikringen 8, Stockholm, 10:15
Opponent
Supervisors
Note

QC 20101112

Available from: 2006-05-24 Created: 2006-05-24 Last updated: 2017-02-22Bibliographically approved
List of papers
1. A Waveguide Finite Element Model Of A Pneumatic Tyre
Open this publication in new window or tab >>A Waveguide Finite Element Model Of A Pneumatic Tyre
2007 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568Article in journal (Other academic) Submitted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-8616 (URN)
Note
QS 20120316Available from: 2008-06-03 Created: 2008-06-03 Last updated: 2017-12-14Bibliographically approved
2. Power dissipation in car tyres
Open this publication in new window or tab >>Power dissipation in car tyres
2008 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568Article in journal (Other academic) Submitted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-5799 (URN)
Note
QS 20120314Available from: 2006-05-24 Created: 2006-05-24 Last updated: 2017-12-14Bibliographically approved

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