**The Chosen Aspects of Materials and Construction Influence on the Tire Safety**

Pavel Koštial, Jan Krmela, Karel Frydrýšek and Ivan Ružiak

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/46506

## **1. Introduction**

264 Composites and Their Properties

Japan.

Composites: Part B 27:447-58.

[10] Goldsmith W, Dharan CK.,Chang H (1995) Quasi-static and ballistic perforation of

[11] Almohandes AA, Abdel – Kader MS, Eleiche, AM (1996) Experimental investigation of the ballistic resistance of steel-fiberglass reinforced polyester laminated plates.

[12] Bardal E, Eggen T G, Rogne T, Solem T (1995) The erosion and corrosion properties of thermal spray and other coatings, in: Proceedings of the Int. Therm. Spray. Conf., Kobe,

[13] Puget Y, Tretheway K R,Wood R J K (1998) The performance of cost effective coatings in

[14] Burstein G T, Sasaki K (2000) Effect of impact angle on the slurry erosion–corrosion of

[15] Dawson J L, Shih C C, John C C, Eden D A (1987), Electrochemical testing of differential flow induced corrosion using jet impingement rigs, NACE Corrosion, Paper no. 453,. [16] Clark H M, Wong K K, Impact angle (1995), particle energy and mass loss in erosion by

[17] Stack M M, Zhou S, Newman R C, Identifications of transitions in erosion–corrosion

[18] Sherrington.(1988), modern measurement techniques in surface metrology, wear

[19] Matsuno Y., Yamada H., Harada M. and Kobayashi A. (1975), The microtopography of

[21] Girardi M. A and Phill M. G. (1993), Microstructure and properties of polyester/urethane acrylate thermosetting blends, and their use as composite matrices,

Journal of Materials Science, Volume 28. 3116-3124, DOI: 10.1007/BF00354718. [22] Mohamed Thariq. (2007), High velocity Impact analysis of glass epoxy-laminate plates.

carbon fiber laminates .Int J Solid Struct VOL(32):89-103.

aggressive saline environments, NACE Corrosion PP 688.

regimes in aqueous environments, Wear 186 (1995) 523–532.

the grinding wheel surface with SEM, Ann.CIRP VOL(24):PP 237-242.

304 L stainless steel, Wear VOL (240): 80–94.

dilute slurries, Wear 186–187 454–464.

[20] Nakamura, Y et al (2003). Neurosci. Abst. 608.5

Thesis, university Putra, Malaysia, Malaysia.

VOL(125):271-288.

Security of the road transport depends on the quality of basic and applied research concerning materials and internal construction of tires. The design shapes and material properties characterized by low hysteretic losses as well as a construction have an influence on the driving comfort, adhesion, wear resistance and fatigue resistance. Thick fibre reinforced composites are used extensively in rubber products such as tires and conveyer belts. Generally, the reinforced parts of rubber products on a sub macroscopic level are highly heterogeneous and anisotropic because they are composed of rubber compounds, and textile and steel cords. Rubber compounds consist of natural or synthetic rubber, carbon black, curing agents, cure accelerators, plasticizers, protective agents and other ingredients.

First, the properties of the different parts of the studied tire will be outlined. A bead is a part of the tire, which fixes to the rim. The bead consists of a steel bead wire, a core, a bead filling and a carcass. They help to transmit loading and breaking.

Particularly we will focus our attention on the influence of breaker angle on tire deformation and potential risks resulting from improper breaker construction.

Experimental results of tread and side wall deformation (influenced by rubber blend as well as a breaker construction) measured independently by both line laser and Aramis system are compared with those obtained by computer simulation in Abaqus environment. The tire tread contributes to a good road grip and water expulsion, the multi-ply steel belt optimizes the directional stability and rolling resistance, the steel casing substantially determines the driving comfort, the inner-liner makes the tire airtight, the sidewall protects from lateral scuffing and the effects of the weather, the bead core ensures the tire sits firmly on the rim, and bead reinforcement promotes directional stability and a precise steering response.

© 2012 Frydrýšek et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Frydrýšek et al., licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The high security and long life of a tire can be assured only by its correct assignment to the particular type of vehicle and automobile as show Figure 1 (tires only for road operation, for off-road, combined operation as well as for summer or winter conditions). Tires are divided by type of tire-casing on radial, diagonal, bias-belted and special tire.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 267

**Figure 2.** Definition of tire from various viewpoints

**Figure 3.** Basic requirements of wheels with tires

choice of the computing algorithm.

Tire safety is passive and active - see Figure 4. Passive safety depends on the quality of the production of a tire casing, the applied technology and used materials and in the case of computational modeling also on the accuracy of the performed calculations and appropriate

**Figure 1.** Type of tire by vehicle and construction

Radial tires can be considered as pressure vessels with a maximum pressure given by the particular type of tire. A tire can be generally considered as a statically and dynamically loaded automobile element. The structured view of a tire is apparent from the Figure 2.

The function of wheels with tires is not only to align a car reliably. As can be seen in more detail from the Figure 3 there are more requirements on tires. The main operating requirements on car tires are that car wheels should be as light as possible and at the same time tough, statically and dynamically balanced.

The main requirements on tires are, apart from other things, high wear resistance, optimal deformation characteristics, low rolling resistance, high operational life and safeness, etc. Wheels with tires must meet particular functional requirements given by parameters of tires which affect the running properties of the car, i.e. affect their dynamic behavior (car maneuverability, stability, acceleration, deceleration, driving comfort, etc.).

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 267

**Figure 2.** Definition of tire from various viewpoints

266 Composites and Their Properties

**Figure 1.** Type of tire by vehicle and construction

time tough, statically and dynamically balanced.

The high security and long life of a tire can be assured only by its correct assignment to the particular type of vehicle and automobile as show Figure 1 (tires only for road operation, for off-road, combined operation as well as for summer or winter conditions). Tires are

Radial tires can be considered as pressure vessels with a maximum pressure given by the particular type of tire. A tire can be generally considered as a statically and dynamically loaded automobile element. The structured view of a tire is apparent from the Figure 2.

The function of wheels with tires is not only to align a car reliably. As can be seen in more detail from the Figure 3 there are more requirements on tires. The main operating requirements on car tires are that car wheels should be as light as possible and at the same

The main requirements on tires are, apart from other things, high wear resistance, optimal deformation characteristics, low rolling resistance, high operational life and safeness, etc. Wheels with tires must meet particular functional requirements given by parameters of tires which affect the running properties of the car, i.e. affect their dynamic behavior (car

maneuverability, stability, acceleration, deceleration, driving comfort, etc.).

divided by type of tire-casing on radial, diagonal, bias-belted and special tire.

**Figure 3.** Basic requirements of wheels with tires

Tire safety is passive and active - see Figure 4. Passive safety depends on the quality of the production of a tire casing, the applied technology and used materials and in the case of computational modeling also on the accuracy of the performed calculations and appropriate choice of the computing algorithm.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 269

New features are introduced for high speeds, e.g. electronic systems which warn the drivers in the case a gradual drop of the tire pressure or adjusting systems for inflation based on the temperature load of the tire casing. Each manufacturer protects the results of his developments and patents considering them as private "know-how". Consequently all new

In the material point of view a rubber blend could be considered as a composite material

The dynamic – mechanical properties of such composites can also be described by an elastic, viscous modulus and a loss factor, (Simek 1987, Sepe 1998, Wang 1998, Schaefer 1994, Murayama 1978, Ferry 1980, Jančíková 2006, Jančíková & Švec 2007 and Jakubíková et al 2007). Such properties depend, in turn, on the operating temperature and frequency of the external excitation. Biodegradability of polymers has been studied in (Jakubíková et al 2007).

In a molecular scale, the mechanical properties of rubber blends are influenced mainly by the structure of the blend. The interaction between a matrix and filler plays the most important role and this role is closely connected with dependency of E and G modulus to an applied load or a frequency (both functions have falling tendency and this phenomenon is called Payne effect) (Payne 1965). The polymer in the network loses its identity, and behaves like a filler. The loss factor E'' depends on the dissolution and regeneration speed of the network. It is reflected on the decreasing trend of complex Young's modulus dependence versus increasing sample loading. The values of elastic modulus (E') for vulcanizates without fillers are not changed with the increasing of dynamic deformation (Payne 1965,

The blend properties are characterized by the following parameters: *Tg* is a glass transition temperature, it is influenced by the silica filler, and for not filled rubber it is approximately - *40°C.* The phase shift between stress and strain is the loss angle. It is postulated that the loss

characterizes the adhesion of the tire on a wet road. In the span *60°C* to *80°C* (at the

The breaker angle (see below) also influences the security of a tire as well as the driving comfort and stiffness of a tire. The driving properties of the tire as a whole could be

The work of the authors over a long period of time is devoted to radial tires. The automobile radial tire consists (e.g. cross-sections of selected tire 165 R13 Matador are on the Figures 5 and 6, in detail on the Figures 6 below and 7) of rubber parts and composite structure parts (Figure 8) with textile cords (especially PA 6.6 and PES textile fibers are used) and steel-

substantially improved by optimizing such angle of steel wires of the breaker.

*,* in the temperature span *-10°C to 5°C* (frequency 10000 Hz)

*,* characterizes the rolling resistance

information is only very scarcely available.

which consists of a matrix, a filler and a mesophase.

Medalia 1978 and Maier & Gand Göritz 1996).

frequency 100 Hz) the course of *tan* 

factor, represented by *tan* 

(http://ao4.ee.tut.fi/pdlri).

**2. The tire description** 

cords into tire tread as reinforcements.

**Figure 4.** Viewpoints of tire safety

Requirements on active safeness are particularly high running safety on various types of road surfaces, breakdown resistance, speed resistance and high life of materials used for the production of tires, namely reinforcing materials.

Tire life is affected by many factors (e.g. manufacturing way of a tire, its operation and handling, storage conditions of base materials for tire production etc.) while it's assumed an ideal adhesive bond among the rubber elements in matrix (e.g. an interface between tire tread and textile overlap belt) and the cord reinforcing and rubber drift inside tire carcass, and belts is assumed in this cases. For long life tires must resist during operating to surrounding effects, to negative effects of operation and to other effects, which could lead to wear and degradation processes as are e.g. delaminations. The aim is to avoid fatal road accidents which might be caused by tire casing defects either by neglecting operating conditions of tires (depth of tire tread pattern, tire inflation pressure, use of inappropriate tires with a different structure, etc.) or by bad vulcanization during the manufacturing process creating delaminations.

The tire is during the operation exposed to combined loading as from a mechanical (statical, dynamic) as a temperature point of view (local heating in subzones, overall heating in the tire-tread area permeating into the tire during breaking). Also this has to be considered in defining tire safety at high speeds. For this reason tires and wheels as a unit are modified from the structural point of view, particularly for special army vehicles where even a sudden drop of pressure does not put an end to the operating capability of the vehicle (system with a central collar providing circular indexing of the casing with respect to the wheel rim).

New features are introduced for high speeds, e.g. electronic systems which warn the drivers in the case a gradual drop of the tire pressure or adjusting systems for inflation based on the temperature load of the tire casing. Each manufacturer protects the results of his developments and patents considering them as private "know-how". Consequently all new information is only very scarcely available.

In the material point of view a rubber blend could be considered as a composite material which consists of a matrix, a filler and a mesophase.

The dynamic – mechanical properties of such composites can also be described by an elastic, viscous modulus and a loss factor, (Simek 1987, Sepe 1998, Wang 1998, Schaefer 1994, Murayama 1978, Ferry 1980, Jančíková 2006, Jančíková & Švec 2007 and Jakubíková et al 2007). Such properties depend, in turn, on the operating temperature and frequency of the external excitation. Biodegradability of polymers has been studied in (Jakubíková et al 2007).

In a molecular scale, the mechanical properties of rubber blends are influenced mainly by the structure of the blend. The interaction between a matrix and filler plays the most important role and this role is closely connected with dependency of E and G modulus to an applied load or a frequency (both functions have falling tendency and this phenomenon is called Payne effect) (Payne 1965). The polymer in the network loses its identity, and behaves like a filler. The loss factor E'' depends on the dissolution and regeneration speed of the network. It is reflected on the decreasing trend of complex Young's modulus dependence versus increasing sample loading. The values of elastic modulus (E') for vulcanizates without fillers are not changed with the increasing of dynamic deformation (Payne 1965, Medalia 1978 and Maier & Gand Göritz 1996).

The blend properties are characterized by the following parameters: *Tg* is a glass transition temperature, it is influenced by the silica filler, and for not filled rubber it is approximately - *40°C.* The phase shift between stress and strain is the loss angle. It is postulated that the loss factor, represented by *tan ,* in the temperature span *-10°C to 5°C* (frequency 10000 Hz) characterizes the adhesion of the tire on a wet road. In the span *60°C* to *80°C* (at the frequency 100 Hz) the course of *tan ,* characterizes the rolling resistance (http://ao4.ee.tut.fi/pdlri).

The breaker angle (see below) also influences the security of a tire as well as the driving comfort and stiffness of a tire. The driving properties of the tire as a whole could be substantially improved by optimizing such angle of steel wires of the breaker.

## **2. The tire description**

268 Composites and Their Properties

**Figure 4.** Viewpoints of tire safety

process creating delaminations.

wheel rim).

production of tires, namely reinforcing materials.

Requirements on active safeness are particularly high running safety on various types of road surfaces, breakdown resistance, speed resistance and high life of materials used for the

Tire life is affected by many factors (e.g. manufacturing way of a tire, its operation and handling, storage conditions of base materials for tire production etc.) while it's assumed an ideal adhesive bond among the rubber elements in matrix (e.g. an interface between tire tread and textile overlap belt) and the cord reinforcing and rubber drift inside tire carcass, and belts is assumed in this cases. For long life tires must resist during operating to surrounding effects, to negative effects of operation and to other effects, which could lead to wear and degradation processes as are e.g. delaminations. The aim is to avoid fatal road accidents which might be caused by tire casing defects either by neglecting operating conditions of tires (depth of tire tread pattern, tire inflation pressure, use of inappropriate tires with a different structure, etc.) or by bad vulcanization during the manufacturing

The tire is during the operation exposed to combined loading as from a mechanical (statical, dynamic) as a temperature point of view (local heating in subzones, overall heating in the tire-tread area permeating into the tire during breaking). Also this has to be considered in defining tire safety at high speeds. For this reason tires and wheels as a unit are modified from the structural point of view, particularly for special army vehicles where even a sudden drop of pressure does not put an end to the operating capability of the vehicle (system with a central collar providing circular indexing of the casing with respect to the

The work of the authors over a long period of time is devoted to radial tires. The automobile radial tire consists (e.g. cross-sections of selected tire 165 R13 Matador are on the Figures 5 and 6, in detail on the Figures 6 below and 7) of rubber parts and composite structure parts (Figure 8) with textile cords (especially PA 6.6 and PES textile fibers are used) and steelcords into tire tread as reinforcements.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 271

**Figure 6.** Structure of the tire 165 R 13 [based on Matador] with microstructure of reinforcing plies

detail A in the area of tire crown and detail B at the end of steel-cord belt (below)

**Figure 5.** Cross sections of tire-casing

The composite structure parts applied into radial tires (Figure 8) are:


These structures of tire have got:


So a tire has got characteristic specific deformation properties.

One construction of tire is used for passenger cars, other constructions for trucks, offhighway cars and sports cars. The tires for air transportation, agricultural vehicle, mining machine and other vehicles have got complicated structured in comparison radial tires for passenger cars. The tire structures are differentiated by numbers of reinforcing plies into belt tire, construction of belts, materials and cord-angles, geometry parameters of tire, width of belts etc. These aspects are influenced on final behavior of tires, namely deformation characteristics of tires. It is possible increase of resistance of tire to some degradation processes by suitable tire construction.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 271

270 Composites and Their Properties

**Figure 5.** Cross sections of tire-casing

These structures of tire have got:

processes by suitable tire construction.


So a tire has got characteristic specific deformation properties.


car);

The composite structure parts applied into radial tires (Figure 8) are:


One construction of tire is used for passenger cars, other constructions for trucks, offhighway cars and sports cars. The tires for air transportation, agricultural vehicle, mining machine and other vehicles have got complicated structured in comparison radial tires for passenger cars. The tire structures are differentiated by numbers of reinforcing plies into belt tire, construction of belts, materials and cord-angles, geometry parameters of tire, width of belts etc. These aspects are influenced on final behavior of tires, namely deformation characteristics of tires. It is possible increase of resistance of tire to some degradation

**Figure 6.** Structure of the tire 165 R 13 [based on Matador] with microstructure of reinforcing plies detail A in the area of tire crown and detail B at the end of steel-cord belt (below)

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 273

Two-layer steel-cord belt is used in radial tire *165 R13 Matador* with construction of cord *2x0.30 mm* with texture *961* (number of cord over meter width of belt). The cord angle is *23°,*

Structure – cord orientations of radial tire *22.5"* for truck vehicles presented in the Figure 9

Steel-cords can be in form of thin wire or wire strand with different constructions. Highstrength steels are used exclusively for steel-cord production and good adhesive bond between rubber and cords required. Steel-cord surfaces are modified by chemical-thermal treatment (braze or copperier, Figure 10) to achieve the best adhesive bond of a steel cord and rubber and get it corrosion resistant. The substantial factor, which expressive influence on coherence of whole tire, is good adhesive bonds between reinforcement materials and

**Figure 10.** Steel-cord surface and interface between cord-rubber drift-rubber matrix

the layers are symmetrical.

**Figure 9.** Structure of truck tire in the middle of tire crown

as an example.

rubber parts of tire.

**Figure 7.** Detail C in the middle of tire crown and detail D at the end of the belt layers (below) of different radial tire

**Figure 8.** Composite structures used in tire

Two-layer steel-cord belt is used in radial tire *165 R13 Matador* with construction of cord *2x0.30 mm* with texture *961* (number of cord over meter width of belt). The cord angle is *23°,* the layers are symmetrical.

Structure – cord orientations of radial tire *22.5"* for truck vehicles presented in the Figure 9 as an example.

**Figure 9.** Structure of truck tire in the middle of tire crown

272 Composites and Their Properties

different radial tire

**Figure 8.** Composite structures used in tire

**Figure 7.** Detail C in the middle of tire crown and detail D at the end of the belt layers (below) of

Steel-cords can be in form of thin wire or wire strand with different constructions. Highstrength steels are used exclusively for steel-cord production and good adhesive bond between rubber and cords required. Steel-cord surfaces are modified by chemical-thermal treatment (braze or copperier, Figure 10) to achieve the best adhesive bond of a steel cord and rubber and get it corrosion resistant. The substantial factor, which expressive influence on coherence of whole tire, is good adhesive bonds between reinforcement materials and rubber parts of tire.

**Figure 10.** Steel-cord surface and interface between cord-rubber drift-rubber matrix

The tire steel-cords are exposed to various chemical and thermal influences (Figure 11) during cyclic loading states by tensile-compression in tire loading processes. Account on this the adhesive bond is more exposed to be damaged than the basic materials (steel, textile and rubber). The aggressive environment (e.g. action of salts in winter) activates the corroding process on steel-cord surfaces that can lead to decreasing of the adhesion between reinforcement-and-matrix, which demonstrates itself by negative changes in material properties of steel-cord belts and such of whole tire too.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 275

**Figure 12.** Degradation processes of tire

**Figure 11.** Requirements on reinforcing tire cords

In addition if the tire is in use is defected in tire crown (e.g. defect caused by sharp object as a nail and after the repair is placed back into operation) the initiation of corrosion with faster process is being assumed. Consequently this can lead to gradual or sudden failure of the steel-cords and bonds of steel-cord and rubber with a serious car accident as a final consequence.

Any damage in the area of tire crown, namely into steel-cord belt, is perilous.

## **3. Degradation processes of tires**

Tires are subject to internal and external effects which can more or less cause limit states leading to degradation processes Figure 12. Ones of them marked as very dangerous and unacceptable tire casing damage are so-called separations and delaminations (Figure 13 left). Breakdown or damage is not necessary only at the border of single layer e.g. between the layers of steel-cord belt plies in the tread of tire casing, but also between rubber matrix and reinforcing cords. Delamination between rubber drift-rubber matrix on Figure 13 right.

**Figure 12.** Degradation processes of tire

properties of steel-cord belts and such of whole tire too.

**Figure 11.** Requirements on reinforcing tire cords

**3. Degradation processes of tires** 

consequence.

Figure 13 right.

The tire steel-cords are exposed to various chemical and thermal influences (Figure 11) during cyclic loading states by tensile-compression in tire loading processes. Account on this the adhesive bond is more exposed to be damaged than the basic materials (steel, textile and rubber). The aggressive environment (e.g. action of salts in winter) activates the corroding process on steel-cord surfaces that can lead to decreasing of the adhesion between reinforcement-and-matrix, which demonstrates itself by negative changes in material

In addition if the tire is in use is defected in tire crown (e.g. defect caused by sharp object as a nail and after the repair is placed back into operation) the initiation of corrosion with faster process is being assumed. Consequently this can lead to gradual or sudden failure of the steel-cords and bonds of steel-cord and rubber with a serious car accident as a final

Tires are subject to internal and external effects which can more or less cause limit states leading to degradation processes Figure 12. Ones of them marked as very dangerous and unacceptable tire casing damage are so-called separations and delaminations (Figure 13 left). Breakdown or damage is not necessary only at the border of single layer e.g. between the layers of steel-cord belt plies in the tread of tire casing, but also between rubber matrix and reinforcing cords. Delamination between rubber drift-rubber matrix on

Any damage in the area of tire crown, namely into steel-cord belt, is perilous.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 277

geometry which can initiate vibrations leading to loss of the part's functional ability of

Wear can be of various character (development, place, form, appearance) and leads to the failure of the tire (Figure 15a and 15b). The task of prediction is to find ways how to reduce wear and to postpone initiation of dangerous degradation processes such as delamination and separation and to focus on the removal of initiators of these

Wear due to adverse changes of surfaces results in impairment of properties and behavior of parts. Particularly dangerous is failure in such places where initiation is not assumed to be caused by impairment of the surface. Structural changes in a part are not only responsible for the impairment of its mechanical properties but also of its geometry which can initiate vibrations leading to loss of the part's functional ability. All this resulted in environmental

whole vehicles (automobiles).

degradation processes.

and economical losses.

**Figure 13.** Factitious delamination between belt plies and damage between rubber drift-rubber matrix (right)

Root cause of mentioned degradation processes can be caused by using of low quality materials for the tire in manufacturing process, their incorrect storage leading to early aging especially at rubber compositions, not keeping optimal manufacturing conditions – vulcanization, as well as by the influence of incorrectly pressurized tire and damaged adhesive bond between cords-matrix and belt plies etc. Damaged adhesive bond is greatly decreasing of tire safety during the operation of a vehicle at high speeds. This has a significant influence to the quality of the tire casing expressing by lowering the level of usage (decreasing speed index) or leading to the catastrophic situations. In every case it is mandatory to avoid these premature limiting states.

In tires can be caused:


**Figure 14.** Extreme wear of tire on tread surface; and "cords working-up" (right-photo by Prof. Janíček, VÚT Brno, Czech Republic)

Results of wear due to adverse change (Figure 14) of tire casing surfaces are gave in impairment of mechanical-physics properties of whole tire. This will be influenced the incoming behavior of tire in operation and related interfaces between of tire and surroundings. Particularly dangerous is creation of failure in such places where initiation is not assumed to be caused by impairment of the surface. Structural changes in a part of tire as composites are not only responsible for the impairment of its properties but also of its geometry which can initiate vibrations leading to loss of the part's functional ability of whole vehicles (automobiles).

276 Composites and Their Properties

In tires can be caused:


VÚT Brno, Czech Republic)


(right)

**Figure 13.** Factitious delamination between belt plies and damage between rubber drift-rubber matrix

Root cause of mentioned degradation processes can be caused by using of low quality materials for the tire in manufacturing process, their incorrect storage leading to early aging especially at rubber compositions, not keeping optimal manufacturing conditions – vulcanization, as well as by the influence of incorrectly pressurized tire and damaged adhesive bond between cords-matrix and belt plies etc. Damaged adhesive bond is greatly decreasing of tire safety during the operation of a vehicle at high speeds. This has a significant influence to the quality of the tire casing expressing by lowering the level of usage (decreasing speed index) or leading to the catastrophic situations. In every case it is

**Figure 14.** Extreme wear of tire on tread surface; and "cords working-up" (right-photo by Prof. Janíček,

Results of wear due to adverse change (Figure 14) of tire casing surfaces are gave in impairment of mechanical-physics properties of whole tire. This will be influenced the incoming behavior of tire in operation and related interfaces between of tire and surroundings. Particularly dangerous is creation of failure in such places where initiation is not assumed to be caused by impairment of the surface. Structural changes in a part of tire as composites are not only responsible for the impairment of its properties but also of its

mandatory to avoid these premature limiting states.


Wear can be of various character (development, place, form, appearance) and leads to the failure of the tire (Figure 15a and 15b). The task of prediction is to find ways how to reduce wear and to postpone initiation of dangerous degradation processes such as delamination and separation and to focus on the removal of initiators of these degradation processes.

Wear due to adverse changes of surfaces results in impairment of properties and behavior of parts. Particularly dangerous is failure in such places where initiation is not assumed to be caused by impairment of the surface. Structural changes in a part are not only responsible for the impairment of its mechanical properties but also of its geometry which can initiate vibrations leading to loss of the part's functional ability. All this resulted in environmental and economical losses.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 279

**Figure 16.** Basic requirements on the tire resistance

complicated technical object as a tire.

reinforcements-matrix transit;

of resistance, life etc. can be obtained.

and macrostructure point of view.

good knowledge about:

**4. Testing of tires** 


An appropriate design will help to increase resistance of the tire to certain degradation processes such as e.g. corrosive attacks initiated by local damage of the tire in cases where damaged are the steel cord reinforcements. Design optimization aimed at resistance to degradation and at achievement of longer life can be well performed by computer modelling. The computer modelling has reached such a level that it can work with a great amount of input data which represent the initiation of degradation effects on such a

It is important to design such structure that the tire would be as much resistant to any degradation type as possible. These are required complex approach to experiments and computation of tire from macrostructure and microstructure too. It is necessary to have a



It is necessary to run tests of tires as a whole, as shown in the Figure 17, and tests of individual tire casing components, purposely separated parts etc. This is how an overview which structural modifications can lead to an increase of the level of safety criteria, increase


**Figure 15.** a. Limit states of tire; b. Limit states of tire

Tires must resist during operating to surrounding effects, to negative effects of operation and to other effects, which could lead to wear and degradation processes as are e.g. delamination. Resistance to the following effects is considered (Figure 16):


**Figure 16.** Basic requirements on the tire resistance

An appropriate design will help to increase resistance of the tire to certain degradation processes such as e.g. corrosive attacks initiated by local damage of the tire in cases where damaged are the steel cord reinforcements. Design optimization aimed at resistance to degradation and at achievement of longer life can be well performed by computer modelling. The computer modelling has reached such a level that it can work with a great amount of input data which represent the initiation of degradation effects on such a complicated technical object as a tire.

It is important to design such structure that the tire would be as much resistant to any degradation type as possible. These are required complex approach to experiments and computation of tire from macrostructure and microstructure too. It is necessary to have a good knowledge about:


278 Composites and Their Properties

**Figure 15.** a. Limit states of tire; b. Limit states of tire

with sharp objects;

concentrated forces;

repeated loading cycles;

integrity of the system during operation;

caused by ozone present in atmosphere;

chemicals (in winter – influence of salt solutions);

Tires must resist during operating to surrounding effects, to negative effects of operation and to other effects, which could lead to wear and degradation processes as are e.g.









delamination. Resistance to the following effects is considered (Figure 16):


temperatures and also consequences of contact with the road;


## **4. Testing of tires**

It is necessary to run tests of tires as a whole, as shown in the Figure 17, and tests of individual tire casing components, purposely separated parts etc. This is how an overview which structural modifications can lead to an increase of the level of safety criteria, increase of resistance, life etc. can be obtained.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 281



Material parameters of long-fiber composite structural parts as the tire steel-belt are necessary input data for tire computational models (e.g. steel-cord belt) and for subsequent comparison of computational models with experiments. Knowledge is necessary of the behaviour of composites as belts under mechanical load. These data are obtained by experimental modelling of composite specimens and composite structural parts (matrixes and reinforcement) by static tensile, compression, shear and bending tests. The behaviour of such materials as tire belts under mechanical loading is in many ways different from the behaviour of commonly used technical materials such as steels. In composites, compared with metals, final mechanical properties can be controlled e.g. in the direction of the orientation of fibers-cords. Composites of tire also have elevated fatigue life, by one order higher material damping and are resistant to failure due to their ability to stop growth or decelerate propagation of cracks on the rubber matrix-cord interface. Tests of specific long-fiber composite materials with hyperelastic matrixes (namely steel.-cord belt test sample) are not standardized and neither are the shapes and dimensions of test samples, namely for tensile tests, which are for the observation of mechanical behaviour absolutely essential. For determination of material parameters of rubber matrixes and cord-reinforcements are necessary make experiments in agreement

In composite samples or in samples with a certain content of composite layers of concern are the configurations of cords with respect to the direction of loading which results in a change of the stiffness characteristics. Therefore is necessary to design the geometrically parameters and shapes of one or multi-layer tested samples before experiments. The samples must have


The author Krmela was designed multi-layer test samples with different wide *10, 15* and *25 mm* and of *length 120 mm*. The cord-angle orientations in single-layer specimens are *0°, 22.5°,* 



**5. Test of tire structure** 

with standard specifications.

transverse orientated samples) – see figure 19;




different:

**Figure 17.** Tests of the tire as a whole

**Figure 18.** Static adhesor with detail of contact patch

Also basic statical deformation characteristics of tires can be obtained from a device called statical adhesor (Figure 18), which is available to author. The statical adhesor also enables measurement of data from the contact surface under defined conditions – shape of obstacles, vertical loading and inflation pressure. It is possible to obtain outputs from experiments on statical adhezor:


**Figure 17.** Tests of the tire as a whole

**Figure 18.** Static adhesor with detail of contact patch

statical adhezor:

Also basic statical deformation characteristics of tires can be obtained from a device called statical adhesor (Figure 18), which is available to author. The statical adhesor also enables measurement of data from the contact surface under defined conditions – shape of obstacles, vertical loading and inflation pressure. It is possible to obtain outputs from experiments on


## **5. Test of tire structure**

Material parameters of long-fiber composite structural parts as the tire steel-belt are necessary input data for tire computational models (e.g. steel-cord belt) and for subsequent comparison of computational models with experiments. Knowledge is necessary of the behaviour of composites as belts under mechanical load. These data are obtained by experimental modelling of composite specimens and composite structural parts (matrixes and reinforcement) by static tensile, compression, shear and bending tests. The behaviour of such materials as tire belts under mechanical loading is in many ways different from the behaviour of commonly used technical materials such as steels. In composites, compared with metals, final mechanical properties can be controlled e.g. in the direction of the orientation of fibers-cords. Composites of tire also have elevated fatigue life, by one order higher material damping and are resistant to failure due to their ability to stop growth or decelerate propagation of cracks on the rubber matrix-cord interface. Tests of specific long-fiber composite materials with hyperelastic matrixes (namely steel.-cord belt test sample) are not standardized and neither are the shapes and dimensions of test samples, namely for tensile tests, which are for the observation of mechanical behaviour absolutely essential. For determination of material parameters of rubber matrixes and cord-reinforcements are necessary make experiments in agreement with standard specifications.

In composite samples or in samples with a certain content of composite layers of concern are the configurations of cords with respect to the direction of loading which results in a change of the stiffness characteristics. Therefore is necessary to design the geometrically parameters and shapes of one or multi-layer tested samples before experiments. The samples must have different:


The author Krmela was designed multi-layer test samples with different wide *10, 15* and *25 mm* and of *length 120 mm*. The cord-angle orientations in single-layer specimens are *0°, 22.5°,*  *45°, 67.5°* and *90°.* Two-layer specimens (Figure 19) are symmetrically orientated between top/bottom layer *22.5°, 67.5°, 45°* and asymmetrically orientated with cord-angles *+0°/- 45°* and *+67.5°/+22.5° (*it is *+22.5°/-112.5°,* specimen D) with thickness *4 mm*. Real single and two-layer specimens are presented Figure 20 as an example.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 283

Statical tensile tests of steel-belt samples are important for obtaining knowledge about stiffness characteristics and material parameters. The conditions of the tensile tests are:


As output example from tensile test of two-layer belt for different cord-angle and cord-type Figures 21 and 22 give tensile force-elongation and stress-strain dependences (elongation

**Figure 21.** Outputs from tensile test of steel-cord belt samples – force-elongation dependences


of specimens.


measured on the length between the jaws).

**Figure 19.** Two-layer specimens from plates with cord orientations 45° (left): A – lengthwise symmetrical specimen with 22.5°; B – transverse symmetrical specimen with 67.5°; C – asymmetrical specimen with +0°/-45°; D – asymmetrical specimen with +67.5°/+22.5°; Specimens from plates with cord orientations 90° (right): E – symmetrical specimen with 45°

**Figure 20.** Single-layer specimens of steel-cord belt with wire cord and two-layer specimens with thinwire cord (right)

Also must be determined conditions for individual type of tests, namely:


Statical tensile tests of steel-belt samples are important for obtaining knowledge about stiffness characteristics and material parameters. The conditions of the tensile tests are:


282 Composites and Their Properties

*22.5°, 67.5°,* 

two-layer specimens are presented Figure 20 as an example.

orientations 90° (right): E – symmetrical specimen with 45°


top/bottom layer

wire cord (right)



*45°, 67.5°* and *90°.* Two-layer specimens (Figure 19) are symmetrically orientated between

*45°* and *+67.5°/+22.5° (*it is *+22.5°/-112.5°,* specimen D) with thickness *4 mm*. Real single and

**Figure 19.** Two-layer specimens from plates with cord orientations 45° (left): A – lengthwise symmetrical specimen with 22.5°; B – transverse symmetrical specimen with 67.5°; C – asymmetrical specimen with +0°/-45°; D – asymmetrical specimen with +67.5°/+22.5°; Specimens from plates with cord

**Figure 20.** Single-layer specimens of steel-cord belt with wire cord and two-layer specimens with thin-


Also must be determined conditions for individual type of tests, namely:

(predicate about real deformation behaviors of steel-cord belt plies);


*45°* and asymmetrically orientated with cord-angles *+0°/-*

As output example from tensile test of two-layer belt for different cord-angle and cord-type Figures 21 and 22 give tensile force-elongation and stress-strain dependences (elongation measured on the length between the jaws).

**Figure 21.** Outputs from tensile test of steel-cord belt samples – force-elongation dependences

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 285

The selected specimens were subject to statical tensile, also compression, shear and bending tests. Also testing conditions have been designed. Tests is necessary perform not only at ambient temperature 20°C but also at lowered and elevated temperature (from -30° into

It will be possible uniform statically test conditions for samples affected by corrosion and

Selected single and two-layer composite test specimens are exposed to corrosion tests in a corrosion chamber *Gebr. Liebisch S 400 M TR* (for 500 or 265 hours in saline application by temperature at 70°Celsius – authors note: such extreme conditions should not ever appear in tire operations if proper conditions are kept) and to static tensile tests till the failure. The aim of these tests is to find the influence of the degrading process on the stiffness characteristics of the composite structures. Also will be investigated an influence of degree of degradation

**Figure 24.** Outputs from tensile test of steel-cord belt samples – stress-strain dependences

180°Celsius).

**6. Corrosion test of steel-cord belt** 

on the adhesive bond matrix-reinforcement.

samples without corrosion.

**Figure 22.** Outputs from tensile test of steel-cord belt samples – stress-strain dependences

Figure 23 presents some examples of specimens' failure after tensile test.

**Figure 23.** Failure of two-layer symmetrical ±22.5° and asymmetrical specimens +67.5°/+22.5° (right) after tensile test

The selected specimens were subject to statical tensile, also compression, shear and bending tests. Also testing conditions have been designed. Tests is necessary perform not only at ambient temperature 20°C but also at lowered and elevated temperature (from -30° into 180°Celsius).

## **6. Corrosion test of steel-cord belt**

284 Composites and Their Properties

after tensile test

**Figure 22.** Outputs from tensile test of steel-cord belt samples – stress-strain dependences

**Figure 23.** Failure of two-layer symmetrical ±22.5° and asymmetrical specimens +67.5°/+22.5° (right)

Figure 23 presents some examples of specimens' failure after tensile test.

It will be possible uniform statically test conditions for samples affected by corrosion and samples without corrosion.

Selected single and two-layer composite test specimens are exposed to corrosion tests in a corrosion chamber *Gebr. Liebisch S 400 M TR* (for 500 or 265 hours in saline application by temperature at 70°Celsius – authors note: such extreme conditions should not ever appear in tire operations if proper conditions are kept) and to static tensile tests till the failure. The aim of these tests is to find the influence of the degrading process on the stiffness characteristics of the composite structures. Also will be investigated an influence of degree of degradation on the adhesive bond matrix-reinforcement.

**Figure 24.** Outputs from tensile test of steel-cord belt samples – stress-strain dependences

The results obtained from tensile test will be compared with results obtained from tensile test on samples without corrosion. The experimental results of tensile tests of undamaged (non-corrosion) steel-cord belt ply (two-layer with cord-angle 22.5°) for comparison analyses with belt ply after corrosion tests are shown in Figure 24 as dependences stress on strain.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 287

Microscopy with *100x-200x* zoom will be used for the evaluation of adhesive bonds from level of failure point of view. It appears that sufficient zoom from setting of failure level point of view (detection of delaminations, separations).It is necessary to prepare of samples


The corrosion processes on cords are shown Figure 27. The results from microscopy

for microscopy observation of structures so that the samples included different:

corrosion, after corrosion test behind extremely conditions).





**Figure 27.** Corrosion processes on steel-cord surfaces – thin wire versus wire (right)

**Figure 28.** Good adhesive bond between wire steel cord 2+20.28 mm (cord consists of 4 filaments) and


For selected cords were accounted:

observation are presented in Figures 28-33.

rubber after tire production (without corrosion)


The influence of corrosion on the stiffness and tensile force-elongation or engineering-stress dependences is sizable. The oxide film is strongly affected on failure of adhesive bond.

The fracture characters of test specimen after tensile and corrosion test in a corrosion chamber were accounted. The fracture of test specimen with *22.5°* angle and thin wire cord is on Figure 25 as an example. The corrosion processes on cord surfaces is very dangerous. Therefore, it will be important to study also adhesive bond.

**Figure 25.** Fracture character of specimen with corrosion after tensile test

## **7. Metallography of Interface between Cord-Rubber**

The light microscope is used for metallography observations of the adhesive bond between steel-cord and rubber after failure after corrosion test in corrosion chamber and statically tensile test and without corrosion too. The edges of steel-cord belt specimens were observed in detail – (see Figures 25 and 26).

**Figure 26.** Interface between thin wire steel-cord/rubber drift/rubber matrix after corrosion and tensile tests

Microscopy with *100x-200x* zoom will be used for the evaluation of adhesive bonds from level of failure point of view. It appears that sufficient zoom from setting of failure level point of view (detection of delaminations, separations).It is necessary to prepare of samples for microscopy observation of structures so that the samples included different:


286 Composites and Their Properties

strain.

The results obtained from tensile test will be compared with results obtained from tensile test on samples without corrosion. The experimental results of tensile tests of undamaged (non-corrosion) steel-cord belt ply (two-layer with cord-angle 22.5°) for comparison analyses with belt ply after corrosion tests are shown in Figure 24 as dependences stress on

The influence of corrosion on the stiffness and tensile force-elongation or engineering-stress dependences is sizable. The oxide film is strongly affected on failure of adhesive bond.

The fracture characters of test specimen after tensile and corrosion test in a corrosion chamber were accounted. The fracture of test specimen with *22.5°* angle and thin wire cord is on Figure 25 as an example. The corrosion processes on cord surfaces is very dangerous.

The light microscope is used for metallography observations of the adhesive bond between steel-cord and rubber after failure after corrosion test in corrosion chamber and statically tensile test and without corrosion too. The edges of steel-cord belt specimens were observed

**Figure 26.** Interface between thin wire steel-cord/rubber drift/rubber matrix after corrosion and tensile

Therefore, it will be important to study also adhesive bond.

**Figure 25.** Fracture character of specimen with corrosion after tensile test

**7. Metallography of Interface between Cord-Rubber** 

in detail – (see Figures 25 and 26).

tests


For selected cords were accounted:


The corrosion processes on cords are shown Figure 27. The results from microscopy observation are presented in Figures 28-33.

**Figure 27.** Corrosion processes on steel-cord surfaces – thin wire versus wire (right)

**Figure 28.** Good adhesive bond between wire steel cord 2+20.28 mm (cord consists of 4 filaments) and rubber after tire production (without corrosion)

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 289

**Figure 32.** Damaged adhesive bond between thin-wire steel cord 0.94 mm and rubber drift after corrosive attack (with extreme corrosion and tensile loading) with detail of oxide on cord surfaces


**Figure 33.** Damaged whole thin-wire steel cord 0.94 mm

On the base of corrosion tests is possible note:



**Figure 29.** Damaged adhesive bond between wire steel cord 2+20.28 mm and rubber after corrosive attack (with extreme corrosion and tensile loading) with detail of oxide on filament surfaces

**Figure 30.** Damaged whole wire steel cord 2+20.28 mm

**Figure 31.** Good adhesive bond between thin-wire steel cord 0.94 mm and rubber drift after tire

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 289

**Figure 32.** Damaged adhesive bond between thin-wire steel cord 0.94 mm and rubber drift after corrosive attack (with extreme corrosion and tensile loading) with detail of oxide on cord surfaces

**Figure 33.** Damaged whole thin-wire steel cord 0.94 mm

On the base of corrosion tests is possible note:


288 Composites and Their Properties

**Figure 29.** Damaged adhesive bond between wire steel cord 2+20.28 mm and rubber after corrosive

attack (with extreme corrosion and tensile loading) with detail of oxide on filament surfaces

**Figure 31.** Good adhesive bond between thin-wire steel cord 0.94 mm and rubber drift after tire

**Figure 30.** Damaged whole wire steel cord 2+20.28 mm


The adhesive bonds are influenced internal impacts (inserted during production, mounting) and external impacts (operating conditions, surrounding conditions etc.) or their interaction. It can be caused degradation on reinforcement-matrix adhesive bond, when its effect is failure into whole macro volume of tire which isn't permissible from safety aspect of vehicle. The Chosen Aspects of Materials and Construction Influence on the Tire Safety 291

**Figure 35.** The measuring system for a sidewall displacement measurement

Hardness of vulcanizate [ShA] 85 Tear resistance [kNm-1]

Modulus 300% [MPa] 15 Elongation [%]

Modulus 300% [MPa] 12 Strength [MPa] 16.5 Elongation [%] 285

Hardness of vulcanizate [ShA] 60 Modulus 300% [MPa] 7.2 Strength [MPa] 17.9 Elongation [%] 570

III. mixture

I. mixture Properties S T D Hardness of vulcanizate [ShA] 73 Strength , LOP, [MPa] 19.23 17.08 23.27

Strength [MPa] 16.2 17.4 Elongation [%] 340 Hardness [ShA] 58 66 72 II. mixture Elasticity [%] 35 18 48

> at 20°C at 90°C

**Table 1.** The physical parameters of bead core blends (left) and other part of the tire (right part).

The sidewall displacement changes caused by both, bead core and the breaker angle, were measured by a contactless system Aramis. This system is able to measure changes of the displacements (radial and axial) during the rotation of the tire. More experimental details about the apparatus are in the work (Koštial et al 2005) (see Figure 35.) The statistically evaluated precision of both described equipments at the actual arrangement of the apparatus was 0.05mm (the result of ten independent measurements on the same tire). The radial loading was *7360 N* (that is 80% of the maximum available load) with a tire inflation

Modulus 300% [MPa]

565 7.8

57.1 43.4 495 9.2

37.5 29.9 440

74.8 74.3


## **8. Dynamic testing**

In this part we continue with a description of dynamic materials behavior as well as a dynamic tire testing.

The tread displacement changes caused by the breaker angle changes were measured by an apparatus presented in Figure 34. The apparatus consists of a line laser, CCD camera and a computer with an appropriate measuring software. The CCD camera records the changes of the line laser spot, which copies the tire dimension changes. This system measures the main dimension of the rotating tire (the illuminated part of tread) at constant velocity. For more details see the work (Koštial et al 2006).

**Figure 34.** The measuring system for a tread deformation

**Figure 35.** The measuring system for a sidewall displacement measurement

protection.

**8. Dynamic testing** 

dynamic tire testing.

with experimental modeling.

details see the work (Koštial et al 2006).

**Figure 34.** The measuring system for a tread deformation

operating safety of the whole tires.

The adhesive bonds are influenced internal impacts (inserted during production, mounting) and external impacts (operating conditions, surrounding conditions etc.) or their interaction. It can be caused degradation on reinforcement-matrix adhesive bond, when its effect is failure into whole macro volume of tire which isn't permissible from safety aspect of vehicle.




In this part we continue with a description of dynamic materials behavior as well as a

The tread displacement changes caused by the breaker angle changes were measured by an apparatus presented in Figure 34. The apparatus consists of a line laser, CCD camera and a computer with an appropriate measuring software. The CCD camera records the changes of the line laser spot, which copies the tire dimension changes. This system measures the main dimension of the rotating tire (the illuminated part of tread) at constant velocity. For more


damaged and safety of steel-cord belt plies and also tire is decreased.


**Table 1.** The physical parameters of bead core blends (left) and other part of the tire (right part).

The sidewall displacement changes caused by both, bead core and the breaker angle, were measured by a contactless system Aramis. This system is able to measure changes of the displacements (radial and axial) during the rotation of the tire. More experimental details about the apparatus are in the work (Koštial et al 2005) (see Figure 35.) The statistically evaluated precision of both described equipments at the actual arrangement of the apparatus was 0.05mm (the result of ten independent measurements on the same tire). The radial loading was *7360 N* (that is 80% of the maximum available load) with a tire inflation of *290 kPa*. After the tire conditioning (30 min at the velocity 80 km/h) the tire inflation increased (due to heat generation at the tire movement) to a pressure of *310-320 kPa.* The considered testing velocities were *10, 50, 80, 120, 150 and 180 km/h*. The reference velocity was *10 km/h* (zeroth stage). The image of a sidewall obtained at *10 km/h* is compared with other images obtained at different velocities. The difference between those images determines a displacement.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 293

are collected in Table 1 – right part. The abbreviations used in Table 1 mean: *S* – sidewall rubber mixture, *T* – tread rubber mixture and *D* – depositional rubber mixture on the steel

The measurements of the sidewall displacement at the contact of the driving drum and tire presented in Figure 36 also show the smallest radial and axial value for the sidewall containing the blend *II.* The upper line is for the reference velocity *10 km/h.* The minimum showing at the bottom of every picture (for axial displacement) corresponds to the velocity of *180 km/h*. According to the presented results it is possible to conclude that in the current case the blend *II* has the best properties (the smallest displacement of a sidewall means higher mechanical stiffness and smaller rolling resistance, for instance) for the sidewall construction. Further we will analyze the changes of the tread and sidewall displacement caused by changes of breaker angle with unchanged bead core blend. The tread and sidewall materials were also the same according to the description presented above

**Figure 37.** The electronic picture of a tread with characteristic points marked as "segments"

Figure 37 shows the electronic picture of the tread with characteristic points marked as "segments" obtained by an optical system with a line laser. The tread displacement changes in radial direction (at above defined velocities) caused by a breaker angle change are visible

Rising of the breaker angle changes the shape of the tread deformation from convex to concave. The best solution was obtained for the breaker angle equals *27°*, where practically the full profile of the tread is in contact with the road. In order to study the influence of breaker angle changes on "sidewall displacement dynamic" at different velocities we also tested the sidewall displacement changes (measured by ARAMIS, breaking angle equal to

cord.

(Table 1).

in Figure 38.

**Figure 36.** The axial displacement changes at the contact (left side) and radial displacement (right side) for three different bead core blends. Unwinded means a length of a given sidewall part.

The physical parameters of the bead core blends are described in the left part of Table 1. The characteristic physical parameters blends used for the construction of the other part of a tire are collected in Table 1 – right part. The abbreviations used in Table 1 mean: *S* – sidewall rubber mixture, *T* – tread rubber mixture and *D* – depositional rubber mixture on the steel cord.

292 Composites and Their Properties

determines a displacement.

of *290 kPa*. After the tire conditioning (30 min at the velocity 80 km/h) the tire inflation increased (due to heat generation at the tire movement) to a pressure of *310-320 kPa.* The considered testing velocities were *10, 50, 80, 120, 150 and 180 km/h*. The reference velocity was *10 km/h* (zeroth stage). The image of a sidewall obtained at *10 km/h* is compared with other images obtained at different velocities. The difference between those images

**Figure 36.** The axial displacement changes at the contact (left side) and radial displacement (right side)

The physical parameters of the bead core blends are described in the left part of Table 1. The characteristic physical parameters blends used for the construction of the other part of a tire

for three different bead core blends. Unwinded means a length of a given sidewall part.

The measurements of the sidewall displacement at the contact of the driving drum and tire presented in Figure 36 also show the smallest radial and axial value for the sidewall containing the blend *II.* The upper line is for the reference velocity *10 km/h.* The minimum showing at the bottom of every picture (for axial displacement) corresponds to the velocity of *180 km/h*. According to the presented results it is possible to conclude that in the current case the blend *II* has the best properties (the smallest displacement of a sidewall means higher mechanical stiffness and smaller rolling resistance, for instance) for the sidewall construction. Further we will analyze the changes of the tread and sidewall displacement caused by changes of breaker angle with unchanged bead core blend. The tread and sidewall materials were also the same according to the description presented above (Table 1).

**Figure 37.** The electronic picture of a tread with characteristic points marked as "segments"

Figure 37 shows the electronic picture of the tread with characteristic points marked as "segments" obtained by an optical system with a line laser. The tread displacement changes in radial direction (at above defined velocities) caused by a breaker angle change are visible in Figure 38.

Rising of the breaker angle changes the shape of the tread deformation from convex to concave. The best solution was obtained for the breaker angle equals *27°*, where practically the full profile of the tread is in contact with the road. In order to study the influence of breaker angle changes on "sidewall displacement dynamic" at different velocities we also tested the sidewall displacement changes (measured by ARAMIS, breaking angle equal to *20*° and 27°). The experimental results of both the axial and radial displacement in this case were compared with those obtained by the *FEM* simulation in *ABAQUS* environment. It is possible to see a good agreement between both simulated and measured curves. Differences occur at higher velocities for radial displacement. Both, the experimental and simulated axial displacements for different velocities and chosen breaker angles (*20*° and 27°) are displayed in Figures 39 and 40. The corresponding simulation and experimental results obtained for radial displacement also show the best results (the highest axial displacement) for breaker angle *27°*.

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 295

comfort. On the other hand, the highest tear resistivity, 300 % modulus and hardness of the depositional rubber mixture on a steel cord provide all together good tire safety (see

**Figure 39.** The axial (left) and radial (right) displacement of the sidewall for 20° breaker angle

parameters in Table 1).

(s-simulation)

**Figure 38.** The displacement differences for the breaker angle 20° (variant 1 - left) and the displacement differences for the breaker angle 27° (variant 4 - right)

On the basis of these results it is possible to state that the higher the breaker angle the higher the displacement is in both axial and radial directions. In other words, the tire "grows" with rising of the breaker angle.). These results support the highest values of elongation and a relatively high value of strength and elasticity which provide also the so called driving comfort. On the other hand, the highest tear resistivity, 300 % modulus and hardness of the depositional rubber mixture on a steel cord provide all together good tire safety (see parameters in Table 1).

294 Composites and Their Properties

for breaker angle *27°*.

*20*° and 27°). The experimental results of both the axial and radial displacement in this case were compared with those obtained by the *FEM* simulation in *ABAQUS* environment. It is possible to see a good agreement between both simulated and measured curves. Differences occur at higher velocities for radial displacement. Both, the experimental and simulated axial displacements for different velocities and chosen breaker angles (*20*° and 27°) are displayed in Figures 39 and 40. The corresponding simulation and experimental results obtained for radial displacement also show the best results (the highest axial displacement)

**Figure 38.** The displacement differences for the breaker angle 20° (variant 1 - left) and the displacement

On the basis of these results it is possible to state that the higher the breaker angle the higher the displacement is in both axial and radial directions. In other words, the tire "grows" with rising of the breaker angle.). These results support the highest values of elongation and a relatively high value of strength and elasticity which provide also the so called driving

differences for the breaker angle 27° (variant 4 - right)

**Figure 39.** The axial (left) and radial (right) displacement of the sidewall for 20° breaker angle (s-simulation)

The Chosen Aspects of Materials and Construction Influence on the Tire Safety 297

The chapter presents the large scale view on the problem of tire safety concluding materials aspects, damage and experimental testing of tires and tire components materials. For more

information about the solution of tyres, see reference (Krmela 2008).

*Department of Transport Means and Diagnostics, Pardubice, Czech Republic* 

*Department of Material Engineering, Ostrava, Czech Republic* 

*Department of Mechanics of Materials, Ostrava, Czech Republic* 

*University of Pardubice, Jan Perner Transport Faculty,* 

*VŠB – Technical University of Ostrava, Faculty of Metalurgy and Material Engineering,* 

*ING-PAED IGIP, VŠB – Technical University of Ostrava, Faculty of Mechanical Engineering,* 

The work has been supported by the Czech grant projects MPO FR-TI3/818 (sponsored by the Ministry of Industry and Trade of the Czech Republic) and by the Slovak-Czech grant project 7AMB12SK126 (sponsored by the Ministry of Education, Youth and Sports of the

Ferry, J. D. (1980). *Viscoelastic properties of Polymers*; John Wiley&Sons, New York, 1980 Jakubíková, Z.; Skalková, P.; Mošková, Z. (2007). Mechanical, Thermal Characterization of low Density Polyethylene (LDPE)/Carboxymethylstarch (CMS) Blends, In: *1st Bratislava* 

Jančíková, Z. (2006). *Umělé neuronové sítě v materiálovém inženýrství*, GEPARTS Ostrava,

Koštial, P., Mokryšová, M., Klabník, M., Žiačik, P.; Kopal, I.; Hutyra, J. (2006). *Rubber World.*

Koštial, P., Mokryšová, M., Kopal, I.; Žiačik, P., Rusnáková, S., Klabník, M. (2005). 12th International metrology congress. 2005, Lyon, Collége Francais de Métrologie, France Krmela, J. (2008). *Systems Approach to the Computational Modelling of Tyres - I. Part*, Czech Republic, 2008, pp.1-102, ISBN 978-80-7399-365-8, book written in Czech language

*Young Polymer Scientists workshop BYPoS*. 2007, Bratislava, Slovakia

Maier, P., Gand Göritz, D. (1996). *Kautschuk Gummi Kunststoffe*. 1996, 49, 18

Czech Republic, 2006, written in Czech language

Jančíková, Z., Švec, P. (2007). *Acta Metallurgica Slovana*, 2007, 13, 5

**9. Conclusion** 

**Author details** 

Jan Krmela

Karel Frydrýšek

Czech Republic).

**10. References** 

2006, 233, 4, 18-20

http://ao4.ee.tut.fi/pdlri

**Acknowledgement** 

Pavel Koštial and Ivan Ružiak

**Figure 40.** The axial displacement of the sidewall for 27° breaker angle (s-simulation)

## **9. Conclusion**

296 Composites and Their Properties

**Figure 40.** The axial displacement of the sidewall for 27° breaker angle (s-simulation)

The chapter presents the large scale view on the problem of tire safety concluding materials aspects, damage and experimental testing of tires and tire components materials. For more information about the solution of tyres, see reference (Krmela 2008).

## **Author details**

Pavel Koštial and Ivan Ružiak *VŠB – Technical University of Ostrava, Faculty of Metalurgy and Material Engineering, Department of Material Engineering, Ostrava, Czech Republic* 

Jan Krmela *University of Pardubice, Jan Perner Transport Faculty, Department of Transport Means and Diagnostics, Pardubice, Czech Republic* 

Karel Frydrýšek *ING-PAED IGIP, VŠB – Technical University of Ostrava, Faculty of Mechanical Engineering, Department of Mechanics of Materials, Ostrava, Czech Republic* 

## **Acknowledgement**

The work has been supported by the Czech grant projects MPO FR-TI3/818 (sponsored by the Ministry of Industry and Trade of the Czech Republic) and by the Slovak-Czech grant project 7AMB12SK126 (sponsored by the Ministry of Education, Youth and Sports of the Czech Republic).

## **10. References**

Ferry, J. D. (1980). *Viscoelastic properties of Polymers*; John Wiley&Sons, New York, 1980


Jančíková, Z., Švec, P. (2007). *Acta Metallurgica Slovana*, 2007, 13, 5


Medalia, A. I. (1978) *Rubber Chem. Technol.*, 1978, 51, 437

Murayama, T. (1978). Elsevier scientific publishing company Amsterdam-Oxford-New York, 1978

**Chapter 14** 

© 2012 Nuruzzaman and Chowdhury, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is

distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Nuruzzaman and Chowdhury, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

**Friction and Wear of Polymer and Composites** 

Dewan Muhammad Nuruzzaman and Mohammad Asaduzzaman Chowdhury

Polymer and its composites are finding ever increasing usage for numerous industrial applications in sliding/rolling components such as bearings, rollers, seals, gears, cams, wheels, piston rings, transmission belts, grinding mills and clutches where their self lubricating properties are exploited to avoid the need for oil or grease lubrication with its attendant problems of contamination [1]. However, when the contact between sliding pairs is present, there is the problem of friction and wear. Yamaguchi [2], Hooke et al. [3] and Lawrence and Stolarski [4] reported that the friction coefficient can, generally, be reduced

Several researchers [5-7] observed that the friction force and wear rate depend on roughness of the rubbing surfaces, relative motion, type of material, temperature, normal force, stick slip, relative humidity, lubrication and vibration. The parameters that dictate the tribological performance of polymer and its composites also include polymer molecular structure, processing and treatment, properties, viscoelastic behavior, surface texture etc. [8-11]. There have been also a number of investigations exploring the influence of test conditions, contact geometry and environment on the friction and wear behavior of polymers and composites. Watanabe [12], Tanaka [13] and Bahadur and Tabor [14] reported that the tribological behavior of polyamide, high density polyethylene (HDPE) and their composites is greatly affected by normal load, sliding speed and temperature. Pihtili and Tosun [15,16] showed that applied load and sliding speed play significant role on the wear behavior of polymer and composites. They also showed that applied load has more effect on the wear than the speed for composites. Several authors [17-22] observed that the friction coefficient of polymers and its composites rubbing against metals decreases with the increase in load though some other researchers have different views. Stuart [23] and other researchers [24- 26] showed that value of friction coefficient increases with the increase in load. Friction coefficient and specific wear rate values for different combinations of polymer and its composite were obtained and compared [27]. For all material combinations, it was observed

and the wear resistance increased by selecting the right material combinations.

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/48246

**1. Introduction** 

properly cited.

Payne, A. R. (1965), Wiley Interscience, New York, 1965

Schaefer, R. J. (1994). *Rubber World*. 1994, 11, 17

Sepe, M. P. (1998). *Plastics Design Library Norwich*, New York, USA, 1998

Simek, I. (1987). *Fyzika polymérov*; SVST, Bratislava, Czechoslovakia, 1987, written in Slovak language

Wang, M. J. (1998). *Rubber Chem. and Technol*., 1998, 71, 3
