Tire–pavement tractive rolling contact under turning conditions: towards pavement top-down cracking

2020 ◽  
pp. 1-10
Author(s):  
E. Y. Manyo ◽  
P. Reynaud ◽  
B. Picoux ◽  
R. Tautou ◽  
F. Allou ◽  
...  
Keyword(s):  
Rolling Contact ◽  
Top Down ◽  
Tractive Rolling

Incipient Slip Conditions in the Rolling Contact of Tyred Wheels

2010 ◽  
Vol 224 (10) ◽  
pp. 2049-2054 ◽  
Author(s):  
S Reina ◽  
D A Hills ◽  
D Dini
Keyword(s):  
Contact Problem ◽  
Closed Form ◽  
Rolling Contact ◽  
Simplified Model ◽  
Practical Case ◽  
Closed Form Solutions ◽  
Steel Wheel ◽  
State Of Stress ◽  
Wide Range ◽  
Tractive Rolling

The contact problem of a driving tyred wheel, pressed and rolling over an elastically similar half-plane, is considered. Although applicable to a wide range of shrink-fitted assemblies, the simplified model is solved to study the practical case of an elastically similar steel tyre mounted on a locomotive steel wheel subjected to tractive rolling. The behaviour of the system at the tyre—substrate interface is studied using closed-form solutions to calculate the state of stress within the tyre. Conditions leading to incipient slip and/or plasticity are identified and mapped for different loads and geometries.

Application of Selected Multiaxial High-Cycle Fatigue Criteria to Rolling Contact Problems

2013 ◽  
Vol 542 ◽  
pp. 157-170 ◽  
Author(s):  
Paweł Romanowicz
Keyword(s):  
High Cycle Fatigue ◽  
Rolling Contact Fatigue ◽  
Roller Bearing ◽  
Three Dimensional ◽  
Contact Fatigue ◽  
Contact Problems ◽  
Rolling Contact ◽  
Cycle Fatigue ◽  
Contact Conditions ◽  
Tractive Rolling

The risk of fatigue failure of elements working in rolling contact conditions (such as railway wheels, rolling bearings, etc.) is a significant issue with respect to safety and economy. In this case the complex and non-proportional stress state with pulsating three dimensional compression occurs. Therefore, the analysis of fatigue life of structures working in rolling contact conditions can be performed using recently proposed multiaxial high-cycle fatigue criteria. However, there is no hypothesis that could be universally accepted for calculations of fatigue strength. Furthermore, not all criteria proposed in literature for rolling contact fatigue (RCF) analysis can predict it. In the paper, the most popular criteria based on different theories are investigated in the application to RCF problem. Moreover, modification of the popular Dang Van hypothesis is proposed. The problem of free and tractive rolling contact fatigue is analysed on the example of a cylindrical crane wheel and spherical thrust roller bearing.

Vertical Short Crack Initiation in Medium Carbon Bainitic Steel Under Mild Tractive Rolling Contact

2008 ◽  
Vol 15 (3) ◽  
pp. 37-41 ◽  
Author(s):  
Peng Dou ◽  
Shuang-fu Suo ◽  
Bing-zhe Bai ◽  
Zhi-gang Yang ◽  
You-guo Li
Keyword(s):  
Crack Initiation ◽  
Short Crack ◽  
Rolling Contact ◽  
Bainitic Steel ◽  
Medium Carbon ◽  
Tractive Rolling

Ratcheting short crack behavior in medium carbon bainitic back-up roll steel under mild tractive rolling contact

Wear ◽  
2010 ◽  
Vol 268 (1-2) ◽  
pp. 302-308 ◽  
Author(s):  
Peng Dou ◽  
Shuangfu Suo ◽  
Zhigang Yang ◽  
Youguo Li ◽  
Darong Chen
Keyword(s):  
Short Crack ◽  
Rolling Contact ◽  
Roll Steel ◽  
Medium Carbon ◽  
Crack Behavior ◽  
Tractive Rolling

scholarly journals Tractive rolling contact mechanics of graded coatings

2012 ◽  
Vol 49 (6) ◽  
pp. 929-945 ◽  
Author(s):  
Mehmet A. Guler ◽  
Saeed Adibnazari ◽  
Yadolah Alinia
Keyword(s):  
Contact Mechanics ◽  
Rolling Contact ◽  
Graded Coatings ◽  
Tractive Rolling

scholarly journals Approach of Pavement Surface Layer Degradation Caused by Tire Contact Using Semi-Analytical Model

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2117
Author(s):  
Edem Yawo Manyo ◽  
Benoit Picoux ◽  
Philippe Reynaud ◽  
Rémi Tautou ◽  
Daniel Nelias ◽  
...  
Keyword(s):  
Service Life ◽  
Rolling Contact ◽  
Transverse Cracks ◽  
Road Design ◽  
Deformation Limit ◽  
Precise Knowledge ◽  
Tractive Rolling ◽  
Micro Deformation ◽  
Stress And Deformation ◽  
The Impact

New methods of degradations on the pavement’s surface, such as top-down cracking and delamination, caused by the repeated passage of heavy vehicles led to questions about the impact of the contact between the tire and the pavement. In fact, to increase the service life of the structures, future road design methods must have a precise knowledge of the consequences of the contact parameters on the state of stress and deformation in the pavement. In this paper, tractive rolling contact under the effect of friction is modeled by Kalker’s theory using a semi-analytical method (SAM). A tire profile is performed thanks to a digitization by fringes or a photogrammetry technique. The effect of rolling on the main surface extension deformations is then highlighted to study top cracking. At the end of the SAM calculation, contact areas are closed to 200 μdef, exceeding the allowable micro-deformation limit for the initiation of cracking. In addition, results on the main strain directions also give information on the direction of cracking (initiation of longitudinal or transverse cracks). The cracking then becomes evident, leading to a reduced service life.

Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment

2004 ◽  
Vol 63 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Fred W. Mast ◽  
Charles M. Oman
Keyword(s):  
Virtual Reality ◽  
Visual Processing ◽  
Line Length ◽  
Perceptual Cues ◽  
Virtual Reality Environment ◽  
Top Down ◽  
Test Conditions ◽  
The Subject ◽  
Processing Mechanisms

The role of top-down processing on the horizontal-vertical line length illusion was examined by means of an ambiguous room with dual visual verticals. In one of the test conditions, the subjects were cued to one of the two verticals and were instructed to cognitively reassign the apparent vertical to the cued orientation. When they have mentally adjusted their perception, two lines in a plus sign configuration appeared and the subjects had to evaluate which line was longer. The results showed that the line length appeared longer when it was aligned with the direction of the vertical currently perceived by the subject. This study provides a demonstration that top-down processing influences lower level visual processing mechanisms. In another test condition, the subjects had all perceptual cues available and the influence was even stronger.

Functional Anatomy of Intensity Aspects of Attention

2003 ◽  
Vol 14 (3) ◽  
pp. 181-190 ◽  
Author(s):  
Walter Sturm
Keyword(s):  
Right Hemisphere ◽  
Functional Anatomy ◽  
Fmri Data ◽  
Functional Networks ◽  
Top Down ◽  
Stimulus Modality ◽  
Spatial Orienting ◽  
Phasic Alertness ◽  
Co Activation ◽  
Attention System

Abstract: Behavioral and PET/fMRI-data are presented to delineate the functional networks subserving alertness, sustained attention, and vigilance as different aspects of attention intensity. The data suggest that a mostly right-hemisphere frontal, parietal, thalamic, and brainstem network plays an important role in the regulation of attention intensity, irrespective of stimulus modality. Under conditions of phasic alertness there is less right frontal activation reflecting a diminished need for top-down regulation with phasic extrinsic stimulation. Furthermore, a high overlap between the functional networks for alerting and spatial orienting of attention is demonstrated. These findings support the hypothesis of a co-activation of the posterior attention system involved in spatial orienting by the anterior alerting network. Possible implications of these findings for the therapy of neglect are proposed.

Auswirkungen eines Aufmerksamkeitstrainings auf die aphasische Symptomatik bei Schlaganfallpatienten

2011 ◽  
Vol 22 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Julia Graf ◽  
Hartwig Kulke ◽  
Christa Sous-Kulke ◽  
Wilfried Schupp ◽  
Stefan Lautenbacher
Keyword(s):  
Top Down

Aufmerksamkeit kann als Kontrollsystem neuronaler Aktivität verstanden werden, welches Neuroplastizität top-down modulieren hilft. Bisher wurde selten versucht, durch deren gezielte Förderung Funktionswiederherstellungen nach Hirnschädigung zu begünstigen. In vorliegender Studie wurde dies am Beispiel der Aphasie erprobt. 15 Schlaganfallpatienten erhielten ein dreiwöchiges Training der selektiven Aufmerksamkeit mit den PC-Programmen CogniPlus und „Konzentration“ bei fünf Sitzungen pro Woche zusätzlich zur Standardtherapie, 13 weitere bildeten eine Kontrollgruppe ohne Aufmerksamkeitstraining. Zur Effektivitätskontrolle dienten zwei Versionen des Untertests Go/Nogo (Testbatterie zur Aufmerksamkeitsprüfung) und die Kurze Aphasieprüfung. Nach dem Training manifestierte sich zwischen den Untersuchungsgruppen kein Unterschied in Aufmerksamkeits- und Sprachfunktionen; das zusätzliche Aufmerksamkeitstraining war also wirkungslos. Allerdings zeigten Patienten mit deutlichen Aufmerksamkeitsverbesserungen tendenziell weniger Aphasie-Symptome, was die Hypothese aufmerksamkeitsvermittelter Plastizitätsmodulation nach Hirnschädigung partiell stützt.

Aufmerksamkeitswechsel und Konzentration: Von den Funktionen zum Mechanismus

2001 ◽  
Vol 209 (1) ◽  
pp. 34-53 ◽  
Author(s):  
Rainer Bösel
Keyword(s):  
Top Down ◽  
Eeg Alpha

Zusammenfassung. Aufmerksamkeit wird sowohl als Selektivität in der bewußter Verarbeitung oder auch als selektive neuronale Aktivierung verstanden. Die neuronalen Strukturen, die Objektdiskrimination ermöglichen, erlauben eine Interaktion von datengetriebenen und endogenen top-down Prozessen, die zu einer selektiven Bereitstellung von Verarbeitungs-Ressourcen führen. Zielgerichtetes Verhalten erfordert manchmal einen Wechsel in der Ressourcen-Bereitstellung und eine Konzentration von mentaler Aktivität. Aufmerksamkeitswechsel kann als ein zweiphasiger Prozeß verstanden werden, der aus einer breiten Mobilisierung von Gedächtnis-Ressourcen besteht (angezeigt durch EEG-Theta), gefolgt von einer re-organisierenden Einengung neuronaler Aktivität (angezeigt durch langsames EEG-Alpha). Dieser Beitrag unterstützt die Annahme, daß die Analyse des gekoppelten Wechselspiels aus Mobilisierung und Konzentration in bestimmten Teilen der posterioren und anterioren Rindenregionen ein Schlüssel für das Verständnis von Aufmerksamkeitswechsel sein könnte.

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