Tribological investigations of the load, temperature, and time dependence of wear in sliding contact (original) (raw)
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Analysis of sliding wear rate variation with nominal contact pressure
2001
The variation of wear rate with nominal contact pressure during sliding wear tests in ballon-flat geometry for two sliding systems was analyzed. Using interrupted wear test data a functional relationship is established between the "instantaneous" wear rate and the nominal contact pressure for M-10 steel (data from literature) and TZP-ZrO 2 materials. The wear rates and the contact pressures were connected by simple wear models that exhibited a variation in wear mechanism. The results show how it is possible to use a simple curve-fitting program to examine the plausibility of various wear models. In M-10 steel, the transition in wear fits very well to a frictional heating model that produces surface softening. In ZrO 2 , stress-induced tetragonal to monoclinic phase transformation is a candidate for the wear mechanism transition.
Simulation of Sliding Wear in Mixed Lubrication
Journal of Tribology, 2007
Sliding wear is a significant surface failure mode in many mechanical components. The magnitude of changes in surface topography due to wear may be comparable to or larger than the original surface roughness and elastic deformation. However, wear has rarely been incorporated into the numerical models used as predictive tools in engineering practice. This paper presents a numerical approach to simulate the wear process based on the deterministic mixed elastohydrodynamic lubrication (EHL) model developed and modified by Zhu and Hu (2001, Tribol. Trans., 44, pp. 383-398). It is assumed that wear takes place at locations where the surfaces are in direct contact, and the wear rate at those local contact spots is proportional to the relative sliding speed, the local contact pressure, and inversely proportional to the hardness of the surface. At each simulation cycle, the distributions of lubricant film thickness and contact pressure are calculated by using the mixed EHL model. The material removal at each contact location is evaluated and the surface topography modified correspondingly. The renewed surface topography is then used for the next cycle. The model is formulated such that any mathematically expressed wear law can be implemented, and therefore, the simulation can be applied to a wide variety of engineering applications.
Analysis of Wear Particles Formed in Boundary-Lubricated Sliding Contacts
The wear process in a sliding contact results in generation of wear debris, which affects the system life. The impact depends on the wear particle properties, such as size, shape and number. In this paper, the wear particles formed during a cylinder-on-disk wear test were examined. PAO additive-free oil, steel–brass and steel–steel contact pairs were employed. A particle isolation procedure was applied, and SEM/EDS analysis was used to validate it. DLS measurements indicated the wear particles radius to be in the range from 230 to 260 nm for both materials under applied nominal pressures from 87 to 175 MPa. AFM data revealed the wear particles size to be in the range from 133 to 175 nm. A slight increase in particles size with load was observed by AFM for both materials and confirmed by DLS for steel samples. AFM measurements were taken to determine thickness, length and width distributions of the wear particles. The number of wear particles per sliding distance and per unit load was estimated to be in the range from 150 to 750 particles mm N for steel and approximately 1600–1900 particles mm N for brass.
Tribologia, 2017
The paper presents wear tests of a sample made of rail steel in a reciprocating motion on an experimental apparatus for surface wear testing. Professional machines for wear tests of rolling-sliding contact, whose main task is to simulate the multiple passage of rolling stock, are large in size and have a significant financial burden on the implementation of scientific projects. The mobile device used for surface wear testing in reciprocating motion has a number of advantages over existing research units with high mass and high financial costs. The proposed device makes it possible to significantly reflect the actual conditions of co-ordination of a rollingsliding contact, for example, the wheel-rail assembly, while maintaining a reasonable financial outlay for the entire project. The results obtained are highly consistent with those obtained under real conditions, which allows us to put forward far-reaching assumptions about the durability of the contact in question and its wear res...
Tribology International, 2016
Wear is a phenomenon that occurs in every technical system and represents the limiting factor in the operational durability. Therefore, it is very important to predict the amount of wear for a tribological system in a reliable manner. In this investigation, different journal bearing materials are investigated in focus of wear behavior in combination with a shaft of steel. The aim of this investigation is to simulate sliding wear on two rough surface profiles in a non-lubricated and mixed-lubricated regime, taking into account the real surface topography of the bearing and the shaft. The whole numerical investigation is taking place at the microscopic level and is modelled with the finite elements software Abaqus (Dessault Simulia) in combination with the programming language Python for applying wear on the rough surfaces. All investigations for the mixedlubricated regime are based on the lubrication model of Lorentz [1] and taking into account the new add-ons described in [2]. Highlights Calculation of wear coefficients using the damage model by Johnson-Cook with the finite-element-method Specification of damage parameters by Johnson-Cook due to a combination of a tensile test and corresponding triaxiality calculations Modelling wear on both rough surfaces of a tribological system using the wear approach by Archard on the microscale level Scaling of wear depths for modelling the friction behaviour for a larger period of tim
Comparison of a tribological model and real component test methods for lubricated contacts
Estonian Journal of Engineering, 2009
The work is aimed to the comparison of tribological performance of lubricated surfaces sliding against each other in laboratory (model test) and real component working conditions. An emphasis is also made on the possibility to use environmental friendly lubricants. The efficiency of using some particular test devices is considered on the basis of available techniques and methods to study lubricated contacts. The implementation of different scales of measurements into the process of materials performance evaluation under tribological conditions is shown to be essential for the reliable assessment of multi-body systems reliability and durability.
Lubricants
The present study proposes the further validation of a simple mathematical procedure recently proposed by the authors to describe contact and wear evolution in line and point contacts. The procedure assumed that the maximum contact pressure could be determined using Hertz equations and a parabolic pressure profile. The contact half-width was obtained using the equilibrium equation and the Archard wear law. Several cases were selected from the literature, reporting experimental data or Finite Element simulations, and the results were compared to those obtained with the proposed approach. This paper confirms the reliability and potentialities of the proposed analytical procedure, which is capable of providing accurate solutions in case of frictional contacts and at the borders of the contact area, where the main discrepancies were found in the previous study.
Wear dynamics of a TPU/steel contact under reciprocal sliding
Wear, 2014
The tribological behavior of a thermoplastic polyurethanes (TPU) sliding against a non-polished steel counterface was studied as a function of load, velocity and temperature under dry conditions. Thermomechanical and chemical analyses were carried out on the TPU using DSC, FTIR and DMTA devices prior to the sliding tests. Contact changes were followed using a speed camera and an acoustic emission device. A simple thermal numerical simulation, to calculate temperature rise generated by friction, completes these analyses. To characterize wear performances, a wear rate was determined by considering the linear dependence between the wear volume and the product of the normal load by the travel distance (Archard model). Finally, wear mechanisms of TPU involve both abrasion scratches and adhesion patterns (Schallamach ridges). To conclude, a wear process description using the third body approach was proposed to gather the whole tribological results.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2006
This paper deals with an experimental study of wear and friction responses from lubricated sliding. Tests were carried out using a tribometer having devices for both continuous and reciprocating motion. The tested specimens were pins of AISI 52100 steel and counter-faces of AISI 8640 steel. The lubricant was paraffin mineral oil, VI 100. The presence of additives and contamination in the lubricant was investigated under two mechanical loading levels, determined by the velocity/load relation. Wear was evaluated in terms of morphology of the worn surfaces and by dimensional analysis of worn area of the pins. It was possible to obtain a ranking of influences on wear of mechanical loading, mechanical motion, oil additive and contamination presence in oil.
Journal of Friction and Wear, 2017
The parameter of the wear law of bronze coupled with steel under dry friction is identified by comparing the results of mathematical modeling with experimental data. The wear tests were carried out according to the steel-ball–flat-bronze sample scheme under relative reciprocal sliding of the tested samples. The modeling of the wear of the sample was based on asymptotic behavior of the solution of the corresponding wear-contact problem. The effectiveness of using this asymptotic behavior to identify the wear law based on the tribological test results has been demonstrated.