ABSTRACT TEZEI DE DOCTORAT
CONTRIBUTIONS TO DYNAMIC ROLLING RADIUS STUDY
FOR VEHICLE’S TIRES”
Author: Lieutenant colonel eng. Valentin IONAŞCU, email: ionascuvalentin@yahoo.com
Scientific guide: Bg.Gl. (ret) univ.prof.eng. Ioan FILIP, Ph.D.
Doctoral thesis approaches a very important topic and precisely the rolling radius, or
more specific named dynamic radius of the wheel. Establishing the value of this parameter has
known and knows different approaches and “refinement”, especially based on experimental
issues, due mainly of randomly elements of the road path.
The paper wishes to be a humble contribution on the way to clarify the phenomenon,
especially on experimental side. The practical determinations of rolling radius on ground field
have had the idea that the basis of the analysis should be the identical behavior of the vehicle’s
wheel during the measurement as in real life, and the results obtained during the tests held on
different kinds of terrain, especially the difficult ones, have to be processed with modern
software equipments, including with statistic evaluations.
The 1st Chapter presents some theoretical elements concerning the vehicle’s wheel
dynamic radius. There are briefly mentioned some essential elements to define the
uncompressed tire radius (r0) and especially the compressed static radius (rS), being mentioned
some experimental methods for measurement of wheel vehicle dynamic radius value.
The 2nd Chapter deals mainly with wheel process simulation issue, having the aim to
determine the dynamic radius values taking into consideration two basic parameters of tubeless
tire, expressly static wheel stiffness and inflating pressure.
The simulation results, expressed by practical determination of vehicle wheel rolling
radius maximal values, are especially important for selecting the most appropriate transducer
able to allow a precise measurement inside the “interval” got by simulations, taking especially
into consideration the constructive dimensions to pay attention to and its mounting restrictions
inside tested vehicle wheel.
The 3rd Chapter aims to present the vehicle preparation for ground field tests, as well as
the measurement chain to be realized in order to get the necessary values of dynamic radius.
There are briefly presented the main measurement chain components with theirs characteristics
and particularities.
The 4th Chapter presents a general analysis of information gotten during the ground
experiments: the tables obtained are quite long, containing generally 12,000 – 13,000 records
for each determination, and are not filtered either hardware or software during acquisition.
The 5th Chapter refers to the main issue of the thesis namely the determination of
dynamic rolling radius of vehicle wheel, starting from the dates obtained during the experimental
tests and measurement of tire deflection, using an ultrasonic sensor attached rigid to the rim.
There were also done some “refinement” operations of dynamic rolling radius values filtering the
original analyzed signal.
The 6th Chapter describes some mathematics modeling of dynamic rolling radius, with
some of most known and used algorithms; these could be generalized and with few minimal
changes could be used in other processes analysis, other then mentioned in present paper.
The 7th Chapter deals with validation of mathematics modeling established on
experimental tests, that is also an other important practical issue.
The final of the paper is devoted to presentation of final conclusions, main personal
contributions and ways ahead; taking into consideration the topic and the author’s contribution,
this issue could be approached in the future by different angles, especially from experimental
point of view, that will consider thoroughly the phenomenon.