Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Rubber is the main component of the pneumatic tire. When rubber is put
under cyclic loading, like when a tire is rolled, heat is generated and stored in
the rubber, due to hysteresis. Heat stored in the tire is increased by factors
like under-inflation, overloading, speeding and defects in the tire. The heat
causes high temperatures in the tire due to the poor thermal conductivity of
rubber. When the temperature in the rubber increases to 185 °C, pyrolysis
and thermo-oxidation starts and can cause the tire to eventually explode.
A numerical model of a rolling passenger vehicle tire was developed to
calculate the temperature distribution inside the tire and analyse the effect
of different operating conditions on the temperature. Operating conditions
include loading, inflation pressure, rolling velocity and ambient temperature.
The tire was modelled by a single rubber type, using the Mooney-Rivlin material
model. The bead wire was modelled using an isotropic material model,
while the body and steel cord plies were modelled as rebars. The cavity, used
to inflate the tire, included the pressure increase due to the volume change,
when the tire is loaded.
The numerical model was validated using experimental data from tests
done on an actual tire. These tests included deformation and contact stress
analysis, as well as surface temperature measurements.
Numerical results showed an increase in temperature when the load, rolling
velocity and the ambient temperature were increased, as well as when the
inflation pressure was decreased. The trends of the numerical data matched the
trends of the experimental data. However, the values of the numerical model
were not consistent with the experimental data due to material properties from
literature being used to model the tire. / AFRIKAANSE OPSOMMING: Rubber is die hoofkomponent in die pneumatiese band. As rubber onder ’n
sikliese las geplaas word, soos wanneer ’n band rol, word hitte gegenereer
en in die rubber gestoor as gevolg van histerese. Die hitte wat in die band
gestoor word, word verhoog deur faktore soos lae inflasiedruk, hoë las, hoë rol
snelhede en gebreke in die band. Die hitte veroorsaak hoë temperature in die
band weens die swak termiese geleiding van rubber. As die temperatuur in die
band hoër as 185 °C raak, vind piroliese en termo-oksidasie plaas en die band
kan uiteindelik ontplof.
’n Numeriese model van ’n passasiersmotorband is ontwikkel om die temperatuurverspreiding
te bepaal, asook om die effek van verskillende werkstoestande
op die temperatuur te analiseer. Die band is gemodelleer met een
tipe rubber en die Mooney-Rivlin materiaal-model is gebruik om die rubber
te beskryf. Die spanrand van die band is deur ’n isotropiese materiaalmodel
gemodelleer, terwyl die hoof- en staalkoordlae as bewapening gemodelleer is.
Die holte wat gebruik word om die band op te blaas, neem die druk toename
as gevolg van die verandering in volume in ag wanneer die band belas word.
Die numeriese model was bekragtig met eksperimentele data wat deur
toetse op ’n werklike band onttrek is. Die toetse sluit die volgende in: vervormingen
kontakspanninganalises, asook temperature wat op die oppervlak van die
band gemeet is.
Die numeriese resultate toon ’n toename in temperatuur wanneer die las,
rolsnelheid en omgewingstemperatuur verhoog word, asook waneer die inflasiedruk
verlaag word. Die numeriese model se tendense stem ooreen met
die eksperimentele data, maar die waardes van die numeriese model is nie in
ooreenstemmig met die eksperimentele data nie. Die verskil is as gevolg van
die materiaaleienskappe wat uit die literatuur geneem is.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/97115 |
| Date | 03 1900 |
| Creators | Maritz, Johannes Christoffel |
| Contributors | Venter, G., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 106 pages : illustrations |
| Rights | Stellenbosch University |
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