Dry Contact Research Articles

A novel strategy to improve melting efficiency and arc stability in underwater FCAW via contact tip air chamber

The conventional method of underwater flux-cored arc welding (UWW-FCAW) is characterized by water around the welding torch's electric parts, the tubular wire, the molten pool and the workpiece. In the present work, underwater FCAW was performed by keeping the contact tip dry, inside a specially developed torch, and as in conventional underwater welding. The welds were carried out in a flat position at simulated depths of 0.3 m, 10 m and 30 m using a hyperbaric chamber. Welding electrical signals of voltage and current and contact tip temperature were acquired and processed to determine process behavior. As a result, the welding current was reduced when the contact tip was kept dry inside the torch because of the higher temperature achieved by resistance heating when it was insulated from the water. The ambient surrounding the contact tip interfered with the coefficient of heat transfer and, consequently, with its temperature. Welds performed with the dry contact tip also presented slight variations in bead shape parameters in different water depths. Higher arc stability was achieved by welding with the contact tip inside the air chamber, as minor variations of electric signals and fewer arc extinction events were observed compared to conventional underwater welds. The combination of improved arc stability with higher electrode temperature may also have contributed to minor porosity and smaller variation of the reinforcement along the weld bead.

Surface effects on elastohydrodynamic lubrication contact of piezoelectric materials with non-Newtonian fluid

Using surface piezoelectricity theory, this article investigates the elastohydrodynamic lubrication (EHL) line contact of a transversely isotropic piezoelectric half-plane with consideration of the surface effect under a rigid cylindrical punch. The surface effect in the surface piezoelectricity theory is mainly described by the following parameters: surface piezoelectric constant, surface dielectric constant, surface elastic constant, and residual surface stress. The punch is treated as an electrical insulator. The lubricant, whose viscosity and density are dependent on fluid pressure, is chosen as a non-Newtonian fluid. Firstly, by analyzing the frictionless dry contact of piezoelectric materials vith the surface effect, the dry contact pressure distribution and the EHL film thickness equation are obtained. Then, an iterative method is proposed to obtain the fluid pressure and film thickness in the lubricant contact region by calculating the fluid–solid coupled nonlinear equations. The effects of the surface dielectric constant, surface piezoelectric constant, surface elastic constant, residual surface stress, punch radius, entraining velocity, and slide/roll ratio on the film thickness and fluid pressure are examined. Our analysis indicates that the surface effect has an essential effect on the EHL contact behavior of piezoelectric materials at micro-/nano-scales.

Effect of alkali treatment on wear behaviour of walnut shell reinforced bio-composites

In this study, the tribological behaviour of composites reinforced with walnut shells (0 % to 10 % at 2 % interval) has been investigated. The pin-on-disc machine is used us to observe the impact of walnut shell addition on the wear properties of the composite. An increase in walnut shell content is associated with diminished wear resistance. Inadequate adhesion among the fibre and the matrix was also identified as the cause of this wear strength degradation in testing results. Pre-treatment of walnut shell with sodium hydroxide increases wear resistance by strengthening matrix adherence to fibre. Different normal loads (from 6 N to 48 N), sliding velocities of 100 cm/s, and sliding distances (SD) of 0 to 2000 m were all considered in the experiments. The findings revealed that operation settings and filler reinforcement have an important impact on the wear behaviour of composite containing walnut shell filler. In comparison to dry and hot contact, the specific wear rate (SWR) is nearly 7 to 8 times lesser in wet conditions. Additionally, equated to a composite with a higher filler loading, the performance of one with a lesser loading of walnut shell filler was superior in terms of wear.

Application of Ultrasonic Tomography to detect defects in Concrete Structures

Concrete is a material widely used in civil construction for structural elements. Due to this, there is an increasing concern about the knowledge of its deterioration state and safety. This stimulates research for methods that allow the evaluation of finished structures. Through the application of Nondestructive Testing (NDT) methods, it is possible to proceed with an investigation of the concrete structures. The application of NDT can contribute to problems diagnosis and quality control of concrete structures. Ultrasound Tomography (UT) tests are an attractive and feasible research strategy. UT allows mapping of the internal section of the object from projections of the same. The tomography uses an antenna, which in turn utilizes a series of dry contact point transducers that emit shear waves into the concrete structures. From the data collected by the equipment, 3D images of the element's reflected interfaces are generated. The present study aims to detect different anomalies that can be found in reinforced concrete slabs, verifying the potential of ultrasonic tomography for the detection of these anomalies. The study was performed by the technical team of the Structural Tests and Materials Laboratory at the Federal University of Rio Grande do Sul (LEME / UFRGS).

Damage assessment in a wheel steel under alternated dry-lubricated contact by an innovative vision system

The alternation of dry and wet contact causes a complex interaction of various damage mechanisms in railway wheels. To study the damage evolution in such condition, rolling-sliding contact tests in alternated dry-wet contact were carried out by a bi-disc machine on specimens extracted from railway wheels. The effect of different durations of the dry and wet sessions was investigated. Two kinds of tests were done: in one case coupling two cylindrical specimens, in the other one coupling a cylindrical specimen with a crowned one. The surface appearance during the tests was acquired by a vision system; the acquired images were elaborated to extract quantitative damage indexes. At the end of the tests, the specimens were cut and analysed, to evaluate the subsurface damage and the strain hardening.In cylindrical-cylindrical coupling, the damage increased in alternated dry-wet sessions as far as the cycle number increased, whereas it was stabilized in long dry sessions. The prevailing phenomenon, occurring during the wet sessions, was fatigue, promoted by the pressurization of the water entrapped in the cracks previously formed in dry contact.In crowned-cylindrical couplings, the damage tended to decrease as far as the cycles increased, in all the test conditions. This was correlated to the widening of the contact patch caused by wear, which led to an overall stress relaxation, this way mitigating the damage.The results highlighted the double role of wear, which alters the optimum wheel profile, but at the meantime relaxes the overall stress state and mitigates rolling contact fatigue.

Effect of the Mechanical Properties of Soft Counter-Faces on the Adhesive Capacity of Mushroom-Shaped Biomimetic Microstructures.

The effects of mechanical properties and contact environment conditions on the adhesiveness of the biomimetic adhesive mushroom-shaped micro-structure have been experimentally investigated. The idea is based on the adhesive micro-structures and surfaces inspired by nature after observing the abilities of some animals. Applications are proposed in various fields of engineering and technology. However, to enable unconventional uses of these biomimetic adhesion surfaces, such as in the biomedical field, it is necessary to adjust and optimize their tribological properties (friction, adhesion, and peeling strength) in contact with soft substrates that can simulate the mechanical features of biological tissues. Our work explores the effect of the combinations of the various parameters on the strength of adhesion. Under dry contact conditions, soft counter-faces lead to lower adhesion than hard counter-faces, whereas under wet conditions, soft counter-faces lead to higher adhesion than harder counter-faces.

A numerical study on the impact of lubricant rheology and surface topography on heavily loaded non-conformal contacts

The increasing requirement of high-power density (power throughput/ weight) in modern day machines lead to thin film lubrication condition in various machine components (rolling element bearings, gears, cams, etc,) due to severe loading conditions. Surface roughness features and lubricant rheology plays a vital role in thin film lubrication, and significantly affects the lubrication performance and lifetime of machine components. The present work demonstrates surface topography and lubricant rheology effects on the traction coefficient for heavily loaded non-conformal contacts. The load-sharing concept considering elastic-plastic deformation of asperities, and Carreau shear-thinning rheological model is employed to describe the dry rough contacts and non-Newtonian behavior of lubricant. An influence of surface topography parameters such as roughness, skewness, kurtosis, and pattern ratio on the traction coefficient is discussed. From results, it is found that among different surface topographies, negatively skewed surfaces having isotropic surface pattern exhibit minimum traction coefficient. The load share function and the critical rolling speed are determined for various surface topographies which provides further insights into the surface topography effect on traction coefficient. The findings of present study are noteworthy as they provide a theoretical basis for an assessment of the lubrication performance of heavily loaded non-conformal contacts.

Enhanced phase method of signal detection for ultrasonic magnetostriction defectoscopy of power equipment

The magnetostrictive method of ultrasonic flaw detection has certain advantages, in particular, the ability to control objects with complex geometry, at their high temperature, the ability to control dry contact between the transducer and the object, difficult access to the controlled area, etc. The peculiarities of the generation of ultrasonic waves by magnetostrictive transducers and their distribution in control objects determine the low level of the signal/noise ratio, which limits the possibilities of practical application of this method. The aim of the paper is to improve the phase method for detecting signals of magnetostrictive receivers with a low signal/noise ratio and to check the effectiveness of the proposed technical solution for solving problems of non-destructive testing of energy equipment elements using magnetostrictive defectoscopes. The paper discusses the phase method of detecting radio pulse signals of magnetostrictive converters against the background of additive noise, which is based on a combination of the capabilities of the discrete Hilbert transformation, which makes it possible to determine the envelope and phase of signals, and methods of statistical processing of the results of phase measurements. The proposed signal processing algorithm was studied both in a model experiment and when processing real magnetostrictive defectoscope signals. The proposed method makes it possible to detect radio pulse signals with a signal/noise ratio close to 1. The reliability of the obtained data is confirmed by the results of computer simulation. The considered method of detecting signals can be used in ultrasonic magnetostrictive defectoscopes and other diagnostic systems operating in conditions of reduced signal/noise ratio. Keywords: magnetostrictive defectoscope, ultrasonic defectoscopy, phase methods of signal processing, Hilbert transform, envelope, phase, sample resulting length of the vector.

Nano and micro-indentation driven characterisation of asperity and bulk plasticity at the surface of modern premium rail steels

The plastic deformation behaviour of rail steels due to cyclic rail-wheel contacts is important to understand due to its connection to wear and rolling contact fatigue (RCF) damage initiation in service. Simulation models such as the ‘Layer’ and ‘Brick’ model have previously been developed to estimate the accumulation of plastic damage in a rail steel; however, the data available to drive these models is currently sparse, with limited applicability to modern rail steel grades. This paper presents the research examining the shear stress-strain curve relationships of rail steels derived from plastic shear strain and shear yield stress data collected from twin-disc test samples. A combination of microhardness and nanohardness testing was used to derive the shear yield stress data, whereas the plastic shear strain was acquired from optical microscopy. Six different conditions were investigated for this research for the purpose of examining how shear stress-strain curve relationships compared between the standard R260 and the premium HP335 and R350HT rail steels and how this compares to wear damage data. The influence of the maximum Hertzian contact pressure on the shear stress-strain curve relationships of R260 between 600 and 1500 MPa contact pressure was also investigated. The wear rate results derived from the mass loss in interrupted twin-disc tests showed HP335 wearing the least, followed by R350HT and then R260 for 1500 MPa, dry contact conditions. However, the highest shear yield stress achieved was for R350HT, then HP335, and R260. The results show that the shear stress-strain curve relationships by themselves are insufficient to determine rail steel wear performance in a laboratory environment. The shear stress-strain curve relationships for R260 collected under different contact pressures showed the results are near independent of the contact pressure within the range explored.

Effects of Lubrication on Wear and Rolling Contact Fatigue Behavior of Class B Wheel Steels Against R350HT Rail Steels Using a Twin-Disc Wear Simulator

Wear and rolling contact fatigue (RCF) are major causes of delays and unavailability of rail systems. The presence of lubricants at the rail and wheel interface influences wear and RCF. Lubricants include naturally occurring types, such as water from rain and leaves from trees next to rail lines, and materials applied on purpose to help improve adhesion and friction, such as friction modifiers, greases, and traction gels. The aim of this work was to study the wear behavior of AAR class B wheel versus R350HT rail materials in the presence of water and oil in comparison with the dry condition. There is currently a lack of knowledge regarding the combination of these materials in a twin-disc simulator, and this work provides information on their impact on RCF and wear performance for use by the rail industries. It was found that wear was much lower when water or oil was introduced at the wheel–rail interface compared to dry conditions, for all slip ratios. When water was used, the main cause of RCF was found to be fluid crack pressurization. The RCF cracks were also observed under dry contact.

Three-dimensional mapping analysis of a capsule system with bilateral elastic constraints

The three-dimensional mapping of the capsule system with bilateral elastic constraints is studied, which is rarely seen in the literature at present. The bilaterally constrained elastic system is suitable for small-scale capsule models. Compared with the unilaterally constrained elastic capsule system, the bilaterally constrained elastic system has a more complex switching mechanism on the boundary, a larger number of local mappings, and a richer whole motion process and bifurcation. The detailed analysis of the bilaterally constrained elastic capsule models can provide more effective theoretical support for the practical application of small-scale capsule models. In this paper, the local dynamics of non-smooth boundaries caused by dry friction and contact and global dynamics in a bilaterally constrained elastic capsule system are analyzed. By considering the vector fields near the boundary surfaces and boundary lines, we get the switching mechanisms on the boundary surfaces and boundary lines and find all possible local mappings. Under the guidance of theoretical analysis, we obtain the sliding bifurcations and boundary-intersection crossing bifurcations by changing the external excitation amplitude. The numerical simulation shows that the bifurcation points and the change of the motion state before and after the bifurcation are consistent with the theoretical results, indicating that this analysis method can be used to accurately discuss the dynamic behaviors of the bilaterally constrained elastic capsule system and mappings can express the dynamic behaviors.

Using the Corner Reflection for Depth Evaluation of Surface Breaking Cracks in Concrete by Ultrasound

The corner echo is a well-known effect in ultrasonic testing, which allows detection of surface breaking cracks with predominantly perpendicular orientation to the surface as, for example, corrosion cracks in metal pipes or shafts. This echo is formed by two planes, the surface of the crack and the surface which the crack breaks. It can also be classified as a half-skip method, since a reflection of the pulse occurs on the backwall before the reflection at the defect takes place. In combination with the diffraction from the crack tip, the corner echo also allows crack sizing. As shown in this paper, the corner reflection can be used in civil engineering for nondestructive inspection of concrete. Commercially available low frequency ultrasonic arrays with dry point contact sources generate SH transversal waves with sufficient divergence of the sound field in order to detect corner reflections. Ultrasonic line-scans and area-scans were acquired with a linear array on flat concrete specimens, and the data were reconstructed by the Synthetic aperture focusing technique. If the angles and the area of reconstruction are chosen accordingly, the corner echo reflection can be distinguished from other ultrasonic information. The corner echo can thus be used as a method for deciding whether a crack is a partial-depth crack or a full-depth crack and thus for obtaining a statement about crack depth. This paper presents corresponding experimental results obtained on concrete specimens with artificial test defects and cracks induced under controlled conditions.

Application of Dry Friction Contact in Vibration Reduction in Engineering—A Short Review

Dry friction contact is widely used to reduce vibration in engineering, especially in the vibration reduction of turbine blades, which are major components of aeroengines [...]

STING controls opioid-induced itch and chronic itch via spinal tank-binding kinase 1-dependent type I interferon response in mice

BackgroundPatients receiving epidural or intrathecal opioids administration for neuraxial analgesia frequently suffer from an irritating itch. STING (stimulator of interferon genes), an innate immune modulator, is strongly implicated in pain pathogenesis via neuron-immune modulation. Given that pain and itch share some common neurocircuits, we evaluate the therapeutic potential of STING agonists in opioid-induced itch and chronic itch.MethodsOpioids (morphine, fentanyl and sufentanil) were intrathecally injected to induce acute itch. Chronic itch was induced by dry skin and contact dermatitis. Opioids analgesic effect, itch-induced scratching behavior, spinal expression of STING, phosphorylation of TBK1 (tank-binding kinase 1), IRF3 (interferon regulatory factor-3) and ERK (extracellular signal-regulated kinase), as well as production of IFN-α and IFN-β were examined. STING agonists (DMXAA and ADU-S100), TBK1 inhibitor, recombinant IFN-α and IFN-β elucidated the mechanism and treatment of itch. Whole-brain functional connectivity was evaluated using resting-state fMRI.ResultsWe report the primary expression of STING protein by the spinal dorsal horn neurons. Intraperitoneal injection of DMXAA dose-dependently reduces morphine-induced scratch bouts, without impairing morphine antinociception. Simultaneously, DMXAA alleviates fentanyl- and sufentanil-induced itching-like behavior, and chronic scratching behavior caused by dry skin and contact dermatitis. Furthermore, DMXAA drastically increases spinal phosphorylation of TBK1 and IRF3 following morphine exposure, dry skin and contact dermatitis. DMXAA-induced anti-pruritus effects and spinal productions of IFN-α and IFN-β are compensated by intrathecal delivery of the TBK1 inhibitor. Also, ADU-S100, recombinant IFN-α and IFN-β exhibits remarkable attenuation in scratching behaviors after morphine injection and dermatitis. Recombinant IFN-α inhibits morphine-induced spinal phosphorylation of ERK. Finally, DMXAA prevents dermatitis-induced the increase of cerebral functional connectivity between regions of interests such as primary somatosensory cortex, piriform cortex, retrosplenial cortex, colliculus and ventral thalamus.ConclusionsSTING activation confers protection against opioid-induced itch and chronic itch through spinal up-regulation of TBK1-IRF3-type I interferon cascades in mice, suggesting that STING agonists are promising candidates in translational development for pruritus relief.

Frictional Response of Reinforced Polymers under Quasistatic and Fast-Transient Dry Contact Conditions

Reinforced polymers have recently gained interest because of their high stiffness associated with the classical features and cost-effectiveness of polymers. A further characteristic, suitable for several applications, is the possibility to provide high frictional and wear resistance. The frictional response of commercially available reinforced materials was here investigated in a wide range of contact boundary conditions. Experimental tests were performed on different test benches, to investigate the material frictional response under either quasistatic or fast-dynamic contact solicitations. While carbon-fiber-reinforced material exhibits a stable but low friction coefficient, the glass-fiber-reinforced material leads to the suitable combination of high friction and low wear. The PPS material, 40% (wt) glass-reinforced polymer, sliding against the Ti6Al4V titanium alloy, provided high static friction coefficients (>0.4). The same material pair was then tested in endurance under fast-dynamic contact solicitations, highlighting their resistance to wear.

Studying electrical parameters of contact and contactless polarization of particles under the electrochemical treatment of mineral suspensions

Introduction. Electrochemical treatment of mineral suspensions is used in electrochemical conditioning of flotation pulp and electrochemical dissolution of minerals and metals in the processes of gold-bearing products electrochemical chlorination. Research objective is to develop and implement the procedures for determining the values of the liquid phase resistance, contact resistance under contact polarization, and ion discharge energy loss resistance under contactless polarization of the electrically conductive part. Methods of research. Equivalent circuits of electrochemical processes have been built for various electrochemical cells. Circuits for various polarizations of electrically conductive particles are established. A formula is proposed for calculating the electrically conductive particle resistance through the electrical resistivity of a unit of volume. A procedure has been developed for calculating the liquid phase resistance through the resistance increment under changing distance between the electrodes. The contact area and pressure influence on the value of the contact resistance is studied through the contact of pyrite and chalcopyrite with an iron electrode. Results. When studying the electrical resistivity of the liquid phase, it was found that increased distance between the current-carrying electrodes leads to an equivalent increase in the liquid phase resistance. It has been established that increased pressure and contact area between the contacting particles and the current-carrying electrode results in decreased contact resistance. The contact resistance between the particle and the electrode in the electrolyte solution is much less than the contact resistance under dry surfaces contact. This phenomenon is explained by electrons tunneling through the electrolyte film. The obtained experimental data on the determination of the liquid phase resistance, contact resistance and ion discharge energy loss resistance make it possible to mathematically describe the processes of electrochemical chlorination under a large number of particles in the pulp. Conclusions and scope of results. Procedures have been developed and specific data have been obtained on the liquid phase resistance, contact resistance, and ion discharge resistance. They can be used for practical application when implementing electrochemical technologies for mineral suspensions treatment.

Influence of the etching process on the coating performance in dry tribological contacts

Physical vapor deposition (PVD) coatings are utilized for wear protection of gears. The use of PVD coatings in unlubricated contacts is also the subject of several research efforts. A promising approach to reduce wear in dry tribological contacts is the combination of MoS2 and WS2 embedded in CrAlN. One possible way to deposit these coatings is the application of High Power Pulse Magnetron Sputtering (HPPMS) process combined with direct current Magnetron Sputtering (dcMS). A challenge by depositing these coatings with an HPPMS/dcMS process is a sufficient adhesion between the coating and the substrate. The present study focuses on the influence of the etching process on the performance of CrAlN + Mo:W:Sg coatings in dry tribological contacts. Before coating deposition, the substrates were pretreated inside the vacuum chamber by different etching processes. During booster etching, which increases the Ar ionization, the substrate bias UB was varied between UB = −150 and UB = −250 V with steps of ΔUB = −50 V. Furthermore, an HPPMS metal ion etching process was used after booster etching at UB = −150 V for these processes. For HPPMS metal ion etching, the number of HPPMS cathodes was varied between one and two. With respect to the etching process, the morphology, surface roughness, compound adhesion by means of the scratch test as well as the coefficient of friction, and the wear volume of the subsequently deposited coatings were investigated. When increasing the substrate bias UB during booster etching, a reduced compound adhesion was found. Moreover, an increased wear volume was observed after pin-on-disk (PoD) tests. For metal ion etching with one activated HPPMS cathode, the wear volume after the PoD test was decreased compared to the pure booster etching processes. When increasing the number of HPPMS cathodes during metal ion etching, the compound adhesion decreased slightly. The wear volume after PoD tests, in contrast, increased. When only using one HPPMS cathode, the lowest wear volume of all investigated coatings was achieved. The present investigations show the potential of tailoring the etching process in order to increase the performance of PVD coatings. A customized HPPMS metal ion etching process can be used to improve the properties of well-established hard PVD coatings.

Base lubricants for green stamping: The effects of their structure and viscosity on tribological performance

The requirements for green and sustainable manufacturing mean that stamping lubricants must be continuously re-evaluated and re-designed. In this investigation, the tribological performance of four base oils with different chemical structures (paraffinic and naphthenic) and viscosities (2 and 20 cSt), as well as water, was evaluated for the stamping of steel sheets and compared with a non-lubricated contact. Most lubricants reduce the coefficient of friction and maintain a similar wear coefficient for steel sheets as in dry contacts. Low-viscosity (LV) naphthenic oil performs very like both high-viscosity (HV) oils. A surprising exception is the LV paraffinic oil, with several-times-higher friction and wear compared to dry contact. This is due to the excellent wetting-spreading and very low cohesion forces that enable oil to escape from extremely thin-film contacts because the viscosity is so low, leading to lubricant starvation. In contrast, HV oils provide a sufficiently thick lubricating film, while strong cohesive forces help in the film’s strength, lessening wear, and reducing friction. In thin-film lubrication with LV oils, such as when stamping, it is thus extremely important that the lubricant’s wetting behaviour and viscosity are sufficient to provide enough film in the contact and prevent starvation, thus ensuring lower friction, less wear, and a longer lifetime of the contact.

Wireless portable transducer for nondestructive evaluation applications based on highly nonlinear solitary waves

A novel technique based on highly nonlinear solitary waves (HNSWs) has recently emerged to inspect / monitor engineering structures. The method is based on the actuation and detection of solitary waves propagating along a monoperiodic array of spherical particles, the last of which is in dry point contact with the material to be evaluated or monitored. The technique relies on the proved hypothesis that the dynamic interaction between the waves and the element to be inspected is dependent upon the mechanical properties and the integrity of the element. The method makes use of the so-called HNSW transducer, which consists of the array held within a rigid frame, an electromagnet that enables the excitation of the solitary waves through mechanical impact, and a sensor to detect the waves. The transducer is typically wired to a data acquisition system that controls the excitation and detection of the waves and stores the time series for post-processing. In the study presented in this paper, a portable, small wireless transducer was designed, assembled, and tested. The new instrument enables the characterization of small or soft samples without any wired connection to electronic test equipment. The reliability of the new device was proven by completing a comparative test in which the conventional wired and the novel wireless configuration were used to probe three samples made of different materials, namely steel, PDMS membrane, and Sawbones®. Then, the instrument was used to test the same membrane subjected to different pressures. The results of the experiments successfully proved that the instruments can accurately operate without the support of electronic equipment and can be used to identify subtle differences in soft materials.

Effect of third mediums on the formation and evolution of rail corrugation

In order to study the influence of third mediums on the formation and evolution behaviours of rail corrugation, two series of rolling-sliding tests were performed. Firstly, tests under the dry and different third mediums (oil, grease, water, friction modifier and windblown sand) conditions were conducted to study the influence of third mediums on the formation of rail corrugation. Secondly, rail rollers were first rolled under the dry condition until a stable rail corrugation was formed. Then, water and friction modifier were added into the wheel-rail interface to investigate the role of third mediums on the evolution behaviours of rail corrugation. The results indicated that third mediums had a significant influence on the wheel-rail damage and the formation and evolution of rail corrugation. Compared with the dry condition, both the mass losses and the damage of rail rollers were alleviated under third mediums conditions. The continuous application of third mediums at the wheel-rail interface could alleviate the formation of rail corrugation significantly. When non-solid third mediums existed at the wheel-rail interface (oil, grease, water and friction modifier), no corrugation was observed. In the dynamic windblown sand environment, the corrugation was obviously slighter than that under the dry contact condition. After corrugation was formed on the rail roller, the application of water and friction modifier could alleviate the amplitude of rail corrugation. Furthermore, with the increase in the number of cycles, the amplitude of rail corrugation first increased and then remained nearly stable. Under the dry contact condition, the crack length in the trough was larger than that in the crest. When liquid third mediums were applied, the cracks at the crest were ground away. However, some liquid would enter into the pre-existed crack in the trough, resulting in the severe rolling contact fatigue damage of rail.