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Corrosion is one of the main electrochemical processes that damage metal materials. The combination of cyclic stresses and a corrosive environment causes wear-fatigue damage, called corrosion-mechanical fatigue. The paper investigates the problem of predicting this type of wear-fatigue damage, which occurs in almost all branches of technology, especially in the chemical, oil, metallurgical industries, transport. The work consists of several parts. In the first part a technique for estimating the fatigue limit in a given corrosive environment (direct effect) is developed. The second part analyzes the reverse effect, i.e. the effect of acting stresses on the corrosion rate of metals and alloys, and proposes a method for predicting corrosion-erosion damage with the reverse effect based on the energy criterion. In the future, it is planned to discuss the mechanisms of corrosion-mechanical fatigue with direct and reverse effects at different stages of complex damage.

The article analyzes relationships of the non-uniformity of the initial states and the lifetime of friction pairs and tribo-fatigue systems based on the results of the inspection of the technical condition after operating time and laboratory tests. The non-uniformity of the initial states is determined by the variation within the tolerances of the geometry of the elements due to the manufacturing technology, and its influence on the wear rate, dynamic characteristics and lifetime of mechanical systems is estimated on the example of automobile sliding friction bearing pairs and rolling bearings. A laboratory experiment to assess the performance of a model of a tribo-fatigue system “shaft (steel 45) — roller (25ХГТ (25KhGT) steel)” due to local violation of the shaft geometry during rolling is analyzed. The correlation equations are given that link the integral characteristics of the local process of wear-fatigue damage, based on measurements of the circular contour of the test specimen (coefficients of asymmetry and non-uniformity), with the relative number of cycles until the limiting wear of the tribo-fatigue system “shaft (steel 45) — liner (silumin)” under sliding friction is reached.

Stress-strain state and volumetric damageability in contact vicinity of «car tire–asphalt concrete» tribo-fatigue system for the various combinations of internal pressure in the tire and axle load on the rim was considered. Stressstrain state of all system and volumetric damageability in contact area of tire and asphalt concrete for the various loads were calculated using finite-element modelling. In contact interaction vicinity was considered areas, where maximum stresses occur: asphalt concrete, tire tread and rubber under radial ply. Stress-strain analysis was considered using classical approach by maximum stress and tribo-fatigue approach by damaged volume. Values of maximum stress intensity and volumetric damageability on different values of radial load on the rim and internal pressure in tire are presented. Results of investigations show how values of maximum stress and volumetric damageability are changing by changing loads on car tire, where inner pressure increases from 0.65 to 0.85 MPa and radial load from 6 to 10 kN. A comparison of two different approaches for the analysis of stress-strain state of system elements has shown a greater effectiveness of the tribo-fatigue approach by damageability than the analysis by maximum stresses. The dependence of the volumetric damageability values on loads was more pronounced compared to the dependence of the maximum stress intensity, changes in which in some cases were haphazard when loads changed and did not reflect their influence on the stress-strain state.

To date, many laws of nature have been discovered. The knowledge of each of them led to the accelerated development of the relevant sections of Science and further, as a rule, to progress in any practical area of the community of people. The empirical law of dry friction [1, 2], first formulated by Leonardo da Vinci 500 years ago, went down in history of technology as one of the most applicable laws in engineering calculations [3]. Moreover, our worldview is unthinkable without an understanding of the general processes of movement with friction (as well as movement without friction). All this gives grounds to say: “Friction is an amazing phenomenon of nature” (D. Garkunov). Two hundred years later (after da Vinci) Amonton M., Coulomb C.A., and Euler L. [4–7] made a decisive contribution to the substantiation and understanding of the law of dry friction, and it became classical: the force of sliding friction is proportional to the contact load. Studies show that the classical friction law for the tribo-fatigue system is inaccurate and, therefore, inapplicable. It was established experimentally that the error in estimating the coefficient of friction in a tribo-fatigue system (for example, a “wheel – rail” type, etc.) reaches 60...70 % or more, if we use the classical law of friction for its analysis. Therefore, there is a problem of adjusting the classical law of friction. A set of theoretical and experimental studies was carried out, the results of which make it possible to formulate a generalized law of friction: the friction force is proportional to both contact and non-contact volume loads, if the latter excites a cyclic stress (strain) field in the friction zone. This law describes all the experimental results (more than 100 values of the friction coefficient) with an error of no more than ± 6 %. The widespread use of the proposed generalized law of friction in the engineering is considered as a very urgent task. In conclusion of the article, some directions for further research (theoretical and experimental) are formulated. The article is published in three reports.

The results of the tests for a friction pair “a cylindrical specimen made of 0.45% carbon steel — a prismatic counterspecimen-liner made of polytetrafluoroethylene F4-B” during sliding friction and mechano-sliding fatigue at different levels of contact load are presented. The experimental data are analyzed using the Archard’s equation and are presented as kinetic dependencies of wear and a friction fatigue curve. The concept of the frictional stress intensity factor during sliding friction is introduced, and the expression is proposed that relates the wear rate to this factor and is close in shape to the Paris equation in fatigue fracture mechanics. Satisfactory compliance of the results of testing the metal-polymer tribo-fatigue system to the proposed expression is obtained both under conditions of sliding friction and under mechano-sliding fatigue.

To date, many laws of Nature have been discovered. The knowledge of each of them led to the accelerated development of the relevant sections of science and further, as a rule, to progress in any practical area of the community of people. The empirical law of dry friction [1, 2], first formulated by Leonardo da Vinci 500 years ago, went down in history of technology as one of the most applicable laws in engineering calculations [3]. Moreover, our worldview is unthinkable without an understanding of the general processes of movement with friction (as well as movement without friction). All this gives grounds to say: “Friction is an amazing phenomenon of nature” (D. Garkunov). Two hundred years later (after da Vinci) Amonton M., Coulomb C.A., and Euler L. [4–7] made a decisive contribution to the substantiation and understanding of the law of dry friction, and it became classical: the force of sliding friction is proportional to the contact load. Studies show that the classical friction law for the tribo-fatigue system is inaccurate and, therefore, inapplicable. It was established experimentally that the error in estimating the coefficient of friction in a tribo-fatigue system (for example, a “wheel — rail” type, etc.) reaches 60...70 % or more, if we use the classical law of friction for its analysis. Therefore, there is a problem of adjusting the classical law of friction. A set of theoretical and experimental studies was carried out, the results of which make it possible to formulate a generalized law of friction: the friction force is proportional to both contact and non-contact volume loads, if the latter excites a cyclic stress (strain) field in the friction zone. This law describes all the experimental results (more than 100 values of the friction coefficient) with an error of no more than ±6 %. The widespread use of the proposed generalized law of friction in the engineering is considered as a very urgent task. In conclusion of the article, some directions for further research (theoretical and experimental) are formulated. The article is published in three reports.

The ball joints of vehicles are referred to the steering and suspension critical units. Strength calculation of the ball pin under static loading is usually performed in the practice of designing these units. In the article, the ball joint is considered as a tribo-fatigue system in which the zones that are dangerous in terms of bending stresses and wear are separated from each other, but are caused by the same load. The necessity of estimating the fatigue resistance of the ball pin and taking into account the uneven distribution of wear over the mating surfaces of the ball head and the liner is shown. The work is done in 2 parts. In the first part, the evaluation of the static and fatigue strength of the ball pin is discussed, and in the second, the assessment of the wear resistance of the joint elements and the proposal for a new method for testing the joint model are considered.

The ball joints of vehicles are referred to the steering and suspension critical units. Strength calculation of the ball pin under static loading is usually performed in the practice of designing these units. In the article, the ball joint is considered as a tribo-fatigue system in which the zones that are dangerous in terms of bending stresses and wear are separated from each other, but are caused by the same load. The necessity of estimating the fatigue resistance of the ball pin and taking into account the uneven distribution of wear over the mating surfaces of the ball head and the liner is shown. The work is done in 2 parts. In the first part, the evaluation of the static and fatigue strength of the ball pin is discussed, and in the second, the assessment of the wear resistance of the joint elements and the proposal for a new method for testing the joint model are discussed.

To date, many laws of Nature have been discovered. The knowledge of each of them led to the accelerated development of the relevant sections of Science and further, as a rule, to progress in any practical area of the community of people. The empirical law of dry friction [1, 2], first formulated by Leonardo da Vinci 500 years ago, went down in history of technology as one of the most applicable laws in engineering calculations [3]. Moreover, our worldview is unthinkable without an understanding of the general processes of movement with friction (as well as movement without friction). All this gives grounds to say: “Friction is an amazing phenomenon of nature” (D. Garkunov). Two hundred years later (after da Vinci) Amonton G., Coulomb C.A., and Euler L. [4–7] made a decisive contribution to the substantiation and understanding of the law of dry friction, and it became classical: the force of sliding friction is proportional to the contact load. Studies show that the classical friction law for the tribo-fatigue system is inaccurate and, therefore, inapplicable. It was established experimentally that the error in estimating the coefficient of friction in a tribo-fatigue system (for example, a “wheel – rail” type, etc.) reaches 60...70 % or more, if we use the classical law of friction for its analysis. Therefore, there is a problem of adjusting the classical law of friction. A set of theoretical and experimental studies was carried out, the results of which make it possible to formulate a generalized law of friction: the friction force is proportional to both contact and non-contact volume loads, if the latter excites a cyclic stress (strain) field in the friction zone. This law describes all the experimental results (more than 100 values of the friction coefficient) with an error of no more than ±6 %. The widespread use of the proposed generalized law of friction in the engineering is considered as a very urgent task. In conclusion of the article, some directions for further research (theoretical and experimental) are formulated. The article is published in three reports.

A brief overview of the practical use of the new construction material of MONICA is given. An experimental study was performed for the first time on the analysis of the influence of the microstructural state on fatigue resistance. It is established that the fatigue limit of this material, based on 108 cycles, is not lower than 243 MPa. The role of the stress concentration in the vicinity of nonmetallic (graphite) inclusions on the formation of the fatigue resistance of MONICA is discussed. The ways of possible increase of the fatigue limit of this material up to ∼300 MPa and more are indicated.

This is a review and staging paper on the fundamental problem of “oil pipeline”. An algorithm of its possible complex solution from the positions of tribo-fatigue is proposed and briefly analyzed. In the first approximation, this algorithm is concretized. Some innovative tasks for a priority solution are formulated.

It is a survey-analytical article, which describes a number of criteria of limit states (LS) of complex objects and identifies methods to measure all the parameters necessary for it practical use. It presents the energy theory of LS of tribo-fatigue and mechanothermodynamical (MTD) systems, taking into account the interaction dialectics of efficient energies and therefore irreversible damages under fatigue loading, friction and temperature influence. The fundamental laws of the LS at the combined effects of multi-parameter power factors and the environment are analysed. The experimentally grounded (over 600 experimental results) fundamental MTD function of forecast evaluation of different LS (static, fatigue, contact fracture) for pure metals, non-ferrous alloys, constructional steels and polymer materials is presented.

A multielement clamp-knife-base tribo-fatigue system is considered. This system is the main part of a harvester's cutting instrument. Boundary element approach in indirect statement is used to model boundary conditions for system's elements taking into account contact interaction between them, cutting force applied to the knife and fixings. Stress-strain state of the system is calculated as superposition of solutions for each boundary element to which predetermined surfaces tractions are applied. Damage state of each element of the system is calculated using the model of a solid with dangerous volume. According to this model dangerous volume is a set of elementary volumes in which acting stresses (strains) are greater than the limiting stress (strain). Obtained results show that the choice of material of the knife (steel or high strength cast iron) and the value of cutting force has significant effect on system's stress-strain state and state of damage. [ABSTRACT FROM AUTHOR]

Tribo-fatigue system roller-shaft, working in conditions of contact interaction between the roller and the shaft and the non-contact bending shaft is considered. The stress-strain state of the system is modeled by a superposition of stress states caused by the action of contact forces and non-contact shaft bending strength. The stress distribution under the action of normal and tangential contact force is calculated as a superposition of analytical fundamental solutions for the steady distributed forces over a rectangular area of the half space. The above calculation results show a significant difference of stress-strain state of tribo-fatigue system from that in the contact pair or in the bend shaft.

In article the experimental analysis of laws of influence of the pressure caused by extracontact loading, on change of the moment of a friction and rolling resistance coefficient is carried out. It is shown that cyclic pressure can (depending on test conditions) both to raise, and to reduce rolling resistance coefficient (to 60 %). It is revealed that the greatest deviation of rolling resistance coefficient in tribo-fatigue system from rolling resistance coefficient in similar pair of a friction is observed at the greatest absolute value of a parity of amplitude of cyclic pressure and the greatest value of contact pressure.

Roller/ring tribo-fatigue system which is used in wear-fatigue tests as the model of wheel/rail system is considered. In this system as well as in wheel/rail system stress-strain state is defined by interaction of contact and volume deformation of one of the system elements. These loads in the roller/ring system are defined by single compressive force. Results of finite element simulation of stress-strain state of roller/ring system are presented. Significant change of contact parameters and stresses distributions in this system due to the bending of the ring comparing to the contact pair is shown.

Damage of tribo-fatigue system it is defined on the basis of model of a deformable firm body with dangerous volume. It is shown that such volumes can be calculated on many and various parametres characterising a mechanical condition (components, intensity, stress tensor, etc.). Classification of measures of damage which can be useful in different conditions is given. Conditions of deformation are considered and some criteria for restriction of dangerous volumes are offered. Techniques and results of calculation of dangerous volumes and damage are resulted at contact interaction with a friction. Examples of use of the developed concept for the decision of almost important problems are given.

It is developed two private variants of the known generalised theory of limiting conditions of tribo-fatigue systems: 1) for corrosion conditions energised and 2) taking into account influence of parametres of a stream of oil. According to the first model, the limiting condition of a material (by criteria of static durability or resistance of weariness) is estimated under orresponding characteristic of mechanical properties in air (strength at a stretching, an endurance limit) taking into account influence of speed of corrosion energised in the given environment. The following general law of corrosion-mechanical durability is formulated: product of operating normal pressure on function of corrosion influence is size a constant for the given material in various conditions loading. On the basis of this law logarithmic function of damageability of petrowire pipes depending on operation time is constructed, according to which oil pipeline "Druzhba" pipes can be maintained safely more than 2 terms of amortisation. This conclusion is confirmed by practical operation of a linear part of oil pipeline "Druzhba". The second model essentially differs that for the first time allows to estimate the contribution of near-wall friction at movement of a stream of oil on a pipe under pressure upon change of resistance of metal of corrosion-mechanical weariness.

Dynamic loading of tribo-fatigue system leads to development of non-stationary process of cyclic deformation in a zone of contact interaction. In system a roller/shaft at simultaneous realisation of a rolling friction and not contact bend of a shaft on a contact surface irregular wavy residual damages (the phenomenon troppy) are formed (under certain conditions). On the basis of results of an experimental research of the specified damages observed in process of wear-fatigue tests, the mehaniko-mathematical model which well describes the phenomenon troppy with the account as movements of tribo-fatigue system, and its non-stationary is intense-deformed condition and a condition of damage is constructed. It is shown that wavy damages of rails while in service can be considered as a special case of troppy; it opens ways for effective search of methods of struggle against them.

Highlights: [•] New methods of complex wear-fatigue tests of the materials and elements of systems are presented. [•] Automatic SI-series machines as the new class of test equipment are described. [•] Interaction the processes of friction, wear and mechanical fatigue is discussed. [•] Dependence of friction coefficient on cyclic stresses by non-contact load is shown. [Copyright &y& Elsevier]

Damage models based on the concept of a deformable solid body having a dangerous volume are considered. A procedure for determination of the damage to complex mechanical systems is proposed. Damage assessment of a roller/shaft tribo-fatigue system operating under conditions of contact interaction of its elements and non-contact loading is performed. A significant change of the system damage as compared with the system subjected to separate types of loading is shown. [ABSTRACT FROM AUTHOR]