Corollaro, Alfredo
(2014)
Essentiality of Temperature Management while Modeling and Analyzing Tires Contact Forces.
[Tesi di dottorato]
| Tipologia del documento: |
Tesi di dottorato
|
| Lingua: |
English |
| Titolo: |
Essentiality of Temperature Management while Modeling and Analyzing Tires Contact Forces |
| Autori: |
| Autore | Email |
|---|
| Corollaro, Alfredo | alfredo.corollaro@bridgestone.eu |
|
| Data: |
31 Marzo 2014 |
| Numero di pagine: |
155 |
| Istituzione: |
Università degli Studi di Napoli Federico II |
| Dipartimento: |
Ingegneria Industriale |
| Scuola di dottorato: |
Ingegneria industriale |
| Dottorato: |
Ingegneria dei sistemi meccanici |
| Ciclo di dottorato: |
25 |
| Coordinatore del Corso di dottorato: |
| nome | email |
|---|
| Bozza, Fabio | fabio.bozza@unina.it |
|
| Tutor: |
| nome | email |
|---|
| Russo, Michele | [non definito] | | Ciaravola, Vincenzo | [non definito] |
|
| Data: |
31 Marzo 2014 |
| Numero di pagine: |
155 |
| Parole chiave: |
Tires, Modeling, Temperature, handling |
| Settori scientifico-disciplinari del MIUR: |
Area 09 - Ingegneria industriale e dell'informazione > ING-IND/13 - Meccanica applicata alle macchine |
[error in script]
[error in script]
| Depositato il: |
10 Apr 2014 17:28 |
| Ultima modifica: |
14 Mag 2017 01:00 |
| URI: |
http://www.fedoa.unina.it/id/eprint/9630 |
Abstract
The influence of temperature on tire performance is subject of matter in Research for many years. It is well known that the temperature affects the grip level of the tire and the cornering stiffness at the same time. Anyway, while the influence of temperature on grip level has been deeply investigated in different activities, the influence on cornering stiffness seems to be not sufficiently discussed yet.
As shown in this work, the reason could be that the cornering stiffness is not influenced by the surface temperature – i.e. the temperature that can be measured on the tread surface – but instead by the bulk temperature – i.e. the core of the tire that means everything is between tread surface and inner liner.
Again, different mathematical models, more or less complex, have been developed to simulate the tire performance during the last 20 years. Anyway, one limit of all these models is that they do not consider the influence of temperature.
The purpose of the entire activity has been deeply investigating the influence of the bulk temperature on tire cornering stiffness also implementing a thermal model able to estimate this temperature correcting the cornering stiffness in consequence.
Indoor and outdoor tests have been conducted for the purpose. In particular the activity was focused on the linear range of the tire lateral characteristic (slip angle limited to +- 1°). The indoor test campaign has been performed on the Flat Trac machine using a tire equipped with particular sensors developed by the TUV Automotive and named T3M sensors. These sensors consist of thermo resistances temperature sensitive that can be introduced in the bulk of a tire.
Different procedures to evaluate the cornering stiffness have been performed. The results have been surprising in terms of the temperature reached during the test. The procedures gave back significant difference on bulk temperature involving in considerable different cornering stiffness characteristics.
The outdoor tests have been conducted on the oval track of the Bridgestone European Proving Ground, remaining in the linear range of the characteristic. Also in this case the results have been surprising for some aspects: the tires reached very high bulk temperatures saturating at a value that depends on vertical load (that means the loads on the corners) and on angular velocity (that means the roadway speed). Furthermore the test showed a deep difference between inside and outside shoulder of the tire. This is in line with the negative camber angle influence that loads the inside shoulder more than the outside.
A thermal model has been developed to evaluate the bulk temperature of a tire during its exercise and correcting the cornering stiffness – through Pacejka formulation – taking into account the influence of the temperature itself.
The model is physical, the thickness of the tire is divided into two layers: for both the equations of thermal diffusivity have been written in Matlab/Simulink environment.
A physical model has been implemented even to evaluate the Strain Energy Loss (SEL) – i.e. the energy dissipated by hysteresis. The SEL model is based on different simplifying assumptions that did not influence the results anyway.
All the parameters are easily measurable and the model needed no tuning. In fact even if a certain numbers of scaling factors have been introduced, all of them have been set to 1; few corrections have been needed in the SEL model; anyway always close to unit (0.95-1.1 the maximum variations).
The model has been validated comparing the simulations with the indoor measurements and it appeared very satisfactory. The SEL model in particular gives back great results, taking into account in the right way as the influence of the vertical load as the influence of the roadway speed; this has been confirmed for very different tire specifications (different sizes, different compounds and different constructions).
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