The mechanisms involved during the wet braking of new and worn tires

Todoroff, Violaine; Paupy, Sébastien; Biesse, Frédéric; Chenadec, Yohan Le

doi:10.1080/00423114.2018.1535126

Cited by 12 publications

(13 citation statements)

References 9 publications

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“…The overall decrease of L p for increasing V 0 , depicted in the Fig. 21, is coherent with the measurements of the contact patch length L c deduced from fluorescein visualizations by Todoroff et al 2018 [7].…”

Section: Self-similarity Of the Flowsupporting

confidence: 88%

“…Direct visualizations made by Todoroff et al2018 [7] using fluorescein show a decrease of the contact patch length for increasing values of V 0 . In this section we analyse the influence of V 0 on velocity profiles inside longitudinal grooves, and the possibility to obtain self-similar profiles using a suitable rescaling of the longitudinal coordinate x.…”

Section: Self-similarity Of the Flowmentioning

confidence: 88%

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Analysis of the water flow inside tire grooves of a rolling car using r-PIV

Cabut,

Michard,

Simoens

et al. 2020

Preprint

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In order to better understand the hydroplaning phenomenon, local velocity measurements of water flow are performed inside the tire grooves of a real car rolling through a water puddle. Velocity fields are obtained by combining refraction Particle Image Velocimetry (r-PIV) illumination, seeding fluorescent particles and either the classical 2D2C or a 2D3C stereoscopic recording arrangements. The presence of some bubble columns inside the grooves is highlighted by separate visualisation using fluorescent contrast technique evidencing two phase flow characteristics. A simple predictive model is proposed supporting the r-PIV analysis. It provides useful information to adjust the focusing distance and to understand the effect of the bubble column presence on the recorded r-PIV images, especially for the seeding particles located in the upper part of the grooves, as fluorescent light is attenuated by the bubbles. Also, the predictions provided by the model are compatible with the measurements. The velocity fields inside the grooves are analysed using ensemble averaging performed over a set of independent snapshots, recorded with the same operating parameters. The variability of the longitudinal velocity distribution measured in a groove for several independent runs is explained by different mechanisms, like the random position of fluorescent seeding particles at various height of the groove, the hydrodynamic interactions between longitudinal and transverse grooves, and the random location of the transverse grooves from one run to an other. Three velocity components in cross-sections of the longitudinal grooves are obtained using the stereoscopic arrangement. They are compatible with the presence of some longitudinal vortices also assumed in the litterature. The number of vortices is shown to be dependent on the aspect ratio characterising a groove's rectangular cross-section. We demonstrate, from measurements performed for several car velocities, that the velocity distribution inside longitudinal grooves shows self-similarity when using specific dimensionless length scale and velocity. Hydrodynamic interactions between longitudinal and transverse grooves are discussed on the basis of a mass budget; a fluid/structure interaction mechanism is proposed in order to correlate the overall direction of the flow in a transverse groove with its location inside the contact zone. Finally some physical mechanisms are suggested for the birth of longitudinal vortices.

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Section: Self-similarity Of the Flowsupporting

confidence: 88%

Section: Self-similarity Of the Flowmentioning

confidence: 88%

Analysis of the water flow inside tire grooves of a rolling car using r-PIV

Cabut,

Michard,

Simoens

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…At present, the research on wet grip performance of tires mainly relies on the two methods of real-vehicle test [1][2][3][4][5][6] and finite element simulation. [7][8][9] In order to coordinate the tire label with the road surface classification, D'Apuzzo et al, 1 used experimental methods to find the correlation between the maximum friction coefficient of SRTT tires and the road pavement IFI.…”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9] In order to coordinate the tire label with the road surface classification, D'Apuzzo et al, 1 used experimental methods to find the correlation between the maximum friction coefficient of SRTT tires and the road pavement IFI. Todoroff et al 2 proposed an original approach to analyze braking test results, which can break down and quantify the relative importance of the mechanisms involved during this test. Genovese et al 3 updated the overview of the friction testers, and reviewed the development and use of this equipment, gave a global overview of the measurement methodologies, and classified it according to the working and specimen motion principle.…”

Section: Introductionmentioning

confidence: 99%

A method for tire wet grip performance evaluation based on grounding characteristics

Liang

Shan

Wang

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part D:

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The wet grip performance of tire is one of the important performances affecting vehicle safety. The steering, acceleration, and braking of the vehicle are directly affected by the grounding characteristics between the radial tire and the ground. In order to study the influence of grounding characteristics of the tire on wet grip performance, ten 205/55R16 tires produced by different manufacturers were selected and tested. The grounding characteristics of the tires were tested using an optical test rig for tire grounding pressure distribution, considering inflation pressure distribution, load and wheel alignment. The tire-road contact area was subdivided into five parts, and 69 parameters were used to describe the grounding characteristics. A software was proposed to process the test results automatically, and 69 grounding characteristic parameters of each tire were obtained. Correlation analysis on tire wet grip performance and grounding characteristics was used for selecting the principal parameters. Finally, eight grounding characteristic parameters related to tire wet grip performance was obtained. Among them are five grounding characteristic parameters (central area rectangle ratio, central area width, internal shoulder length-to-width ratio, external and internal shoulder contact area ratio, external and internal shoulder impression area ratio) which have high correlation to tire wet grip performance, and three grounding characteristic parameters (external shoulder width, external shoulder length-to-width ratio, external and internal shoulder width ratio) which have low correlation to the wet grip performance of the tire. The principal component analysis method was used to analyze the highly correlated grounding characteristic parameters, and the regression equation for evaluating tire wet grip performance was fitted. The comparison of experimental and fitted values show that the errors are within 4%. The result demonstrates that, the method for evaluating wet grip performance of the radial tire through tire-road grounding characteristics was achieved.

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“…This causes a total loss of control of the vehicle. It has been demonstrated that current regulatory tests (on vehicle wet braking from 20 to 80 km/h on 1 mm water depth) have some hydroplaning phenomenon when worn tires are used [2]. This is why the design of the grooves of a tire has to be optimized in order to evacuate enough water to avoid hydroplaning.…”

Section: Introductionmentioning

confidence: 99%

Particle Image Velocimetry (PIV) measurements in a water film, application to a tire rolling through a puddle

Cabut

Michard

Simoëns

et al. 2019

Mechanics & Industry

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A measurement method based on Particle Image Velocimetry (PIV) with refraction of the laser sheet at a window/water interface is proposed for the measurement of the velocity field of a flow, inside a water puddle, due to a tire rolling on. This study focuses on the feasibility and repeatability of this optical measurement method. The characterization of the optical properties of this measurement technique defines its accuracy. The analysis of the overall features of the flow is focused on two main flow zones in front of and around the tire. The flow inside the first zone is characterized by a global velocity of the water displaced in an area located in front of the tire. In the second zone a velocity representative of the flow in the vicinity of the tire shoulder is also defined. Correlations of both characteristic velocities with the car speed and water film height are established. New and the corresponding worn tires were tested in this work.

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The mechanisms involved during the wet braking of new and worn tires

Cited by 12 publications

References 9 publications

Analysis of the water flow inside tire grooves of a rolling car using r-PIV

Analysis of the water flow inside tire grooves of a rolling car using r-PIV

A method for tire wet grip performance evaluation based on grounding characteristics

Particle Image Velocimetry (PIV) measurements in a water film, application to a tire rolling through a puddle

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