simulation of torsion moment at the wheel set of the railway vehicle ...

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REVIEWFig. 1 Functions of wheels with tyres and requirements on them [2]Further specific requirements on tyres, e.g. vehicles handlingmaterial in metalworks close to metallurgical furnaces where tyresare exposed to extremely high temperatures are as well as to sharpobjects.3. Definition of a tyreTyres as heterogeneous composite bodies can be defined fromvarious viewpoints as shown in Fig. 2. From a geometrical pointof view the tyre is an annulus, from the viewpoint of strength andflexibility it can be considered as a pressure vessel and with respectto the structure of individual parts of the tyre casing and respectivedifferent properties a tyre can be considered as a part withanisotropic properties. Furthermore, a tyre can be statically anddynamically loaded, which is given by the actual operating condition.A specific requirement on tyres is safety at high speeds and theconsequential measures aimed at preventing fatal road accidents.62 ● COMMUNICATIONS 3/2008
REVIEWFor this reason tyres and wheels as a unit are modified fromthe structural point of view, particularly for special army vehicleswhere even a sudden drop of pressure does not put an end to theoperating capability of the vehicle (system with a central collarproviding circular indexing of the casing with respect to the wheelrim).Fig. 2 Definition of tyre from various viewpoints [2]4. Tyres for high speeds from the viewpoint of safetyTyre safety is passive and active – see Fig. 3. Passive safetydepends on the quality of the production of a tyre casing, the appliedtechnology and used materials and in the case of computationalmodelling also on the accuracy of the performed calculations andappropriate choice of the computing algorithm.Requirements on active safeness are particularly high runningsafety on various types of road surfaces, breakdown resistance,speed resistance and high life of materials used for the productionof tyres, namely reinforcing materials.The aim is to avoid fatal road accidents which might be causedby tyre casing defects either by neglecting operating conditions oftyres (depth of tyre tread pattern, tyre inflation pressure, use of inappropriatetyres with a different structure, etc.) or by bad vulcanizationduring the manufacturing process creating delaminations.Fig. 3 Viewpoints of tyre safety [2]New features are introduced for high speeds, e.g. electronicsystems which warn the drivers in the case a gradual drop of thetyre pressure or adjusting systems for inflation based on the temperatureload of the tyre casing. Each manufacturer protects theresults of his developments and patents considering them as private“know-how”. Consequently, all new information is only very scarcelyavailable.The listing of various structural modifications would lie outsidethe scope of this contribution. Obviously this is an actual topicwhere the use of modern computational methods is advanced andpurposeful.Tyres are subject to internal and external effects which canmore or less cause limit states leading to degradation processes(delamination, etc.).During the operation of a vehicle combined loading of thetyre occurs both from a mechanical (statical, dynamic) and a temperaturepoint of view (local heating in subzones, global heatingin the tyre-tread area permeating into the tyre during breaking).Also this has to be considered in defining tyre safety at highspeeds.5. Requirements on tyre lifeTyres must resist during operating to surrounding effects, tonegative effects of operation and to other effects, which couldlead e.g. to delamination. Resistance to the following effects isconsidered:• puncture – capability of tyre to resist puncture by sharp objects• cut-through – capability of tyre (especially of the tread and sidewall)to resist contact with sharp objects• breakdown – capability of tyre to resist damage during shorttermloading by concentrated forces• fatigue – capability of tyre to resist material fatigue and defectsin consequence of repeated loading cycles• separation and delamination – capability of structural tyre componentsto maintain integrity of the system during operation• humidity – tyre elements must be able to resist degradation bycontact with water• ozone influence – capability of tyre and of its components toresist degradation caused by ozone present in atmosphere• temperature – tyre components must be able to resist high andlow ambient temperatures and also consequences of contactwith the road• chemicals – capability of tyres and their components to resistdegradation caused by chemicals (in winter – influence of saltsolutions).COMMUNICATIONS 3/2008 ●63
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Mt = k$ Di(12) 4. Torsion moment at
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References[1] JOVANOVIC, R.: Tensio
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Page 14 and 15: and D R _ y,wi=0 if y 0 (12) Dampe
Page 16 and 17: Fig. 22 Comfort for passengers for
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Page 20 and 21: Fig. 2 Consignment reloading proces
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Page 24 and 25: Juraj Gerlici - Tomas Lack *MODIFIE
Page 26 and 27: After the insertion of the previous
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Page 30 and 31: [2] GERLICI, J., LACK, T.: Methods
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Page 36 and 37: attained the 6th position of the be
Page 38 and 39: Jozef Jandacka - Stefan Papucik - V
Page 40 and 41: spacing of the fan from the measuri
Page 42 and 43: 5. ConclusionFrom the results prese
Page 44 and 45: REVIEWlines with numerous curves th
Page 46 and 47: REVIEWmeters from the point of view
Page 48 and 49: REVIEWBojan Cene - Aleksandar Rados
Page 50: REVIEWthe year 2006 in Slovenia sta
Page 53 and 54: REVIEWthat the GPS does not recogni
Page 55 and 56: REVIEWRadomir Brkic - Zivoslav Adam
Page 57 and 58: REVIEWfailures. For example, for an
Page 59: REVIEWJan Krmela *COMPUTATIONAL MOD
Page 63 and 64: REVIEWFig. 6 Computational model
Page 65 and 66: REVIEW- guarantee that the messages
Page 67 and 68: REVIEWIvana Olivkova *PASSENGER INF
Page 69 and 70: REVIEWLike the other information sy
Page 71 and 72: REVIEWFig. 1 Revolution of the poin
Page 73 and 74: REVIEWFig. 4 Transformation of the
Page 75 and 76: BOOK REVIEWKavicka, A., Klima, V.,
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