Fractal Approach to Tribology of Elastomers

ISBN-13: 9783319938608 / Angielski / Twarda / 2018 / 401 str.

Ahad Kh Janahmadov; Maksim Javadov

Opis

This book summarizes the results of years of research on the problem of strength and fracture of polymers and elastomers.

Spis treści

Chapter 1. ABOUT THEORETICAL STRENGTH OF MATERIALS

1.1   Theoretical strength of solids

1.2   The relationship between elastic modulus and theoretical strength

1.3   The concept of phonon destruction

1.4   Phonon theory of destruction of polymer chain

1.5   The relationship between mechanical and thermal properties of solids

1.6   Types of cracks

1.7   Non-linear fracture mechanics and fracture criteria

1.8   Griffith theory of fracture of solids

 

Chapter 2. GENERAL LAWS OF FRICTION AND WEAR OF POLYMERS

2.1 The nature and properties of elastomer friction

2.2 Principles of failure of elastomers

2.3 Thermodynamics of failure and criticism of Griffith theory

2.4 The general form of phenomenological theory

2.5 Statistical theory of fatigue fracture

2.6 The mechanism of fatigue failure of elastomers

2.7 The principles of scaling and generalized variables

2.8 The transition to dimensionless parameters. π-theorem

2.9 The stress-relaxation in elastomers and self-sealing effect

2.10 The reasons of absence of self-sealing effect in elastomers

 

Chapter 3. FRACTAL KINETICS OF FRACTURE

3.1 The concept of fractal. Fractal dimension

3.2 Fractals of condensed matter physics

3.3 Fractal properties of hierarchical structure of potential relief

3.4 Kinetics of fracture from the point of theory of fractals

3.5 Analysis of relationship between the fractal dimension of dissipative structure of pre-destruction zone, and the mechanical properties and the critical deformation states of metals and alloys

3.6 Diagnosis of contact interaction of solids using fractal analysis method

3.6.1 The emergence of fractal structures during evolution of complex systems

3.6.2 The dependence of contour pressure roughness at elastic and plastic contacts

3.6.3 The calculation of power spectrum of profile roughness and the diagnosis of contact modes of metallic bodies

 

Chapter 4. MODERN PROBLEMS OF FRICTIONAL CONTACTS OF ELASTOMERS

4.1 Efficient linear-viscoelastic characteristics of non-homogenous elastic (composites) and viscoelastic bodies

4.2 Derivation of expressions of new efficient moduli

4.3 Analytical solution of the problem of loading viscoelastic half-space

4.4 Building approximate solutions with effective time moduli

4.5 Modification of efficient Hashin-Shtrikman moduli for the two-component isotropic composite

4.6 Derivation of expressions of effective Hashin-Shtrikman moduli of racing type

4.7 Models of averaging effective characteristics of the two-component elastic composite

4.7.1 Model of iterative conversion of efficiency characteristics

4.7.2 Model of averaging effective characteristics

4.8 The problem of loading double-layer shell

4.9 The problem of loading triple-layer plates

4.10 Nano-tribological processes during electric discharge in discrete ohmic contacts of “polymer-metal” pairs

4.10.1 Electrical currents in surface and sub-surface layers of polymer lining

4.10.2 Electrical rift in discrete ohmic contacts of metal-polymer pairs of tribosystems

4.10.3 Local fracturing of polymer films in ohmic contacts of tribo-coupling

4.11 The frictional interaction in electric and thermal fields of metal-polymer frictional pairs

4.11.1 Electrical conductivity of surface lining of polymer lining

4.11.2 The contact-impulse interaction of frictional pairs with different energy levels of materials

4.11.3 Selection of materials of electrodes and their behavior at the transition phase of the first kind

4.11.4 The general laws of electrodynamic characteristics of the micro-protrusion contact spots at their frictional interaction

4.11.5 The phenomena of electrical explosion and hear discharge at the frictional interaction in metal-polymer pairs

4.11.6 The phenomena of thermal explosion at frictional interaction of metal-polymer pairs

4.12   Fractal analysis of disperse-filled elastomeric composites

4.12.1 Molecular modeling of mesoscopic polymeric composite systems

4.12.2 Fractal analysis of structure and properties of interphase layers in disperse-filled elastomeric composites. The significant nano-effect of strengthening elastomers by nano-particles

 

Chapter 5. DIMENSION REDUCTION AS MODELING METHOD FOR ELASTOMERS UNDER COMPLEX DYNAMIC LOADING

5.1 Contact mechanics and physics of friction

5.1.1 The depth of indentation as steady controlling parameter of contact configuration

5.1.2 The surface gradient and the size of micro-contact as the main surface parameters

5.1.3 Examples of the generalized friction laws

5.2 Meso-mechanical nature of friction and numerical modelling in tribology

5.2.1 Tribology in the era of information technologies

5.2.2 Mesoscopic nature of friction

5.2.3 Method of dimensionality reduction

5.3 Dimensionality reduction for modelling friction process in elastomers

5.3.1 Main principles of dimensionality reduction

5.3.1.1 Case of normal contacts

5.3.1.2 Case of tangential contacts

5.3.1.3 Viscoelastic contacts and thermal effects

5.3.1.4 Adhesion at viscoelastic contacts

5.3.1.5 Normal contacts on rough surfaces

5.3.1.6 Friction force between the rigid rough surfaces and elastomers

5.3.2 Precise mapping based on dimensionality reduction of axisymmetric contact problems with and without adhesion

5.3.2.1 Axisymmetric contacts without adhesion

5.3.2.2 Mapping theorems of dimensionality reduction

5.3.2.3 Implementation of adhesion

5.4 Dimensionality reduction for modelling friction of elastomers

5.4.1 Modeling friction of elastomers under complex dynamic loading

5.4.1.1 Modeling static coefficient of friction

5.4.1.2 Studying oscillations of pressing normal forces with coefficient of sliding friction

5.4.2 Modeling friction of elastomers at contact with rough surface

5.4.2.1 The dependence of kinetic frictional force on normal force at contact with random roughness of elastomer surface

5.4.2.2 Studying adhesive properties of contacts between elastic bodies with random rough self-affine surfaces using dimensionality reduction

5.4.2.3 Studying dry normal contact between fractal rough surfaces using dimensionality reduction

 

Chapter 6. GENERAL PROBLEMS OF SEALING UNITS AND THEIR CLASSIFICATIONS

6.1 The primary mechanism of sealing units

6.1.1 Classifications of sealants

6.1.2 Leakage of sealing components

6.2 Major groups and design types of rubber sealants

6.2.1 Group of sealants

6.3 Synthesis of sealing downhole packers

6.4 Destructive influence of two-phase fluids on cuffs of screw pumps

 

Chapter 7. Stress-strain state of sealants of complex shapes

7.1 Strain characteristics of casing sealant

7.2 Creeping in casing sealant

7.3 Strain characteristics of casing sealant of complex shape

7.4 Examining stress-strain state of sealing element of casing

7.5 Determination of sealing ability of sealant

7.6 Ensuring effectiveness of sealant

7.7 Effectiveness of radial sealant in hydraulic cylinder

7.8 Influence of geometric shape of sealant on self-sealing

 

Chapter 8. SEALING PROPERTIES OF ELASTIC ELEMENT

8.1 Conditions of self-sealing effect

8.2 Impact of wicking on self-sealing

8.3 Determination of optimal gap between elastic element and operational casing<

8.4 Determination of forces applied to elastic element

8.5 Assessment of impact rate of load to elastic element

8.6 Impact of sealant shape on stress relaxation in contact zone

8.7 Impact of axial force rate on sealing process

 

CONCLUSION

O autorze

Ahad Janahmadov is a scientist and expert in the field of tribology and triboengineering. He has authored over 350 works and was awarded several prizes, more recently the Gold Medal of the Russian Academy of Natural Sciences.

Blurb

This book summarizes the results of years of research on the problem of strength and fracture of polymers and elastomers. It sets out the modern approach to the strength theory from the standpoint of fractals, the kinetic and thermodynamic theories as well as the meso-mechanic destruction. The dimension reduction method is applied to model the friction processes in elastomers subjected to the complex dynamic loading. Finally, it analyses a relation between the fracture mechanism and the relation phenomena, and provides new experimental data on the sealing nodes in accordance with their specific working conditions where the effect of self-sealing is observed.