Friction Lining Research Articles

Torsional refrigeration by twisted, coiled, and supercoiled fibers.

Higher-efficiency, lower-cost refrigeration is needed for both large- and small-scale cooling. Refrigerators using entropy changes during cycles of stretching or hydrostatic compression of a solid are possible alternatives to the vapor-compression fridges found in homes. We show that high cooling results from twist changes for twisted, coiled, or supercoiled fibers, including those of natural rubber, nickel titanium, and polyethylene fishing line. Using opposite chiralities of twist and coiling produces supercoiled natural rubber fibers and coiled fishing line fibers that cool when stretched. A demonstrated twist-based device for cooling flowing water provides high cooling energy and device efficiency. Mechanical calculations describe the axial and spring-index dependencies of twist-enhanced cooling and its origin in a phase transformation for polyethylene fibers.

EFFECT OF ENVIRONMENT ON BROMOBUTYL RUBBER–STEEL ADHESION

ABSTRACT Optimizing the maintenance cycles of rubber-lined components is of great importance. Especially for the industry sectors operating under demanding conditions, challenges in the lifetime evaluation of rubber linings may cause apparent premature failures. Thus, understanding the effect of environmental factors on the performance and durability of rubber linings, as well as on the weakest links of the structure in certain environments, is essential. The performances of bromobutyl rubber and rubber–steel interfaces after exposure to different environments, namely, high temperature (95 °C), moisture (95% relative humidity and immersion), and sulfuric acid (solution with 75 g/L of acid) were investigated. The weakest link of the rubber–metal structure and, consequently, the location of the fracture were mostly within the adhesive layer or at the primer–metal interface. However, the most degraded component of the adhesive system depends on the aging environments.

Research on the coefficient of friction of becorit K22 and K25SB linings

Abstract The article presents the method and results of experimental tests of the coefficient of friction between a steel rope and friction lining. The BECORIT K22 and BECORIT K25SB floor coverings were tested. The tests were carried out in accordance with the recommendations of the new German standard: DIN 21258 – Lubricants and impregnating agents for drive discs and transport ropes in mining – safety and testing requirements. The authors in this article emphasize that the Becorit K22 and K25SB linings are used for the wheels of propeller drums of mining machines. Characterized by high coefficients of friction (μ ≥ 0.25), also in cases of extreme weather conditions on the surface. The chemical properties of BECORIT linings ensure their resistance to swelling in the event of different oils and lubricants as well as mine waters. The material of which the claddings are made ensures very good machinability during rolling of rope grooves with the use of turning or milling tools. BECORIT K22 plastic cladding is particularly suitable for use in hoisting machines, where the rope base forms a large overlap angle on the wheel grooves (max 1°31'), which causes its lateral wear faster. BECORIT K22 material in this case provides a higher service life compared to other materials. Due to the way they are mounted on the wheel, they are made as 1-piece (monolith) or bipartite. In this article, moreover, the structure and principle of operation of the measuring station on which the tests were carried out are presented in great detail.

Improving the Efficiency of the Power Take-Off Drive

power tools that are used in various industries have power take-off drives for aggregating various machines and mechanisms. In the agro-industrial complex, one of the most common power tools are tractors manufactured by the Minsk Tractor Plant. The drive of power take-off in these tractors is carried out at the expense of the planetary mechanism. The wheel and the solar gear of the planetary mechanism are connected to the drums, alternately stopping the drums is carried out on and off the drive. The brake tape of the firing drum connected to the sun gear is most susceptible to wear, as the drum is loaded with a torque of at least one third of the torque to the drive of the aggregated machine.Due to the design features of the existing control mechanism, the turn–on time is 1.5-2 times less than recommended for devices of this kind. As a result, there is an intense wear of the friction lining of the inclusion drum tape.Regulation of the control mechanism of adjusting screws is carried out untimely, as a result, the durability of the tapes is very low.To improve the durability and efficiency of the power take-off drive, a drive-on design is proposed by electromagnets.Applying force to the tape by electromagnets at four points, instead of one in the previous design, will improve the braking efficiency of the inclusion drum.It is possible to include electromagnets not at the same time, but with some time offset, with a gradual pressing of the tape, starting with the portion of the tape closest to the axis of its suspension. This improves the fit of the tape to the drum inclusion.In the transition from a mechanical drive to an electrical device, the control operation is eliminated, which reduces maintenance time, significantly increases the life of the brake belt and increases the efficiency of the power take-off drive.

Experimental and numerical investigation of an axisymmetric divergent dual throat nozzle

The dual throat nozzle achieves higher thrust vectoring efficiencies and lesser thrust loss than other fluidic thrust-vectoring nozzles. Separation always occurs at the bottom of the cavity with complex three-dimensional characteristics for the dual throat nozzle. In this paper, by comparing the flow structure, nozzle surface static pressure distributions and skin friction lines, which are obtained by numerical simulations and wind tunnel experiments, an axisymmetric divergent dual throat nozzle is investigated in detail. The main results show the following findings. (1) The experimental schlieren photographs confirm again that the divergent nozzle configuration has the starting problem from an intuitive perspective. Meanwhile, the flow structure and nozzle surface static pressure distributions obtained by numerical simulations are consistent with the experimental results, except for the low nozzle pressure ratios. (2) The circumferential pressure difference is negligible upstream of the separation line but obvious downstream of the separation line. The skin friction lines and nozzle surface static pressure distributions of different circumferential angles obtained by experiments both prove that the actual flow in the axisymmetric divergent dual throat nozzle indeed possesses three-dimensional characteristics. Therefore, it is necessary to utilize the full three-dimensional computational domain to study the complex three-dimensional characteristics of the flow for the axisymmetric divergent dual throat nozzle thoroughly.

On the Simulation of the Micro-Contact of Rough Surfaces Using the Example of Wet Friction Clutch Materials

Friction behavior in a sliding contact is strongly influenced by the surface topography of the bodies in contact. This also applies to friction clutches. Even small differences in surface topography may cause significant differences in friction behavior. Thus, it is important to be able to characterize the micro-contact of the rough sliding surfaces, which are, in the case of a clutch, steel plate and friction material. One important measure for the characterization of the micro-contact is the real area of contact. Another important aspect is the contact pattern. The article introduces a method to implement a FEM (Finite Element Method) model from real surface measurements. Real surface topography of the friction pairing is considered. The simulation method is applied to different friction pairings and operating conditions. Computational results with rough and smooth steel plates, new and run-in friction linings, and different nominal surface pressure verify the model. In addition, the results on real area of contact between a steel and a friction plate are compared with published values.

Selection of Materials of Friction Lining Centrifugal Brake Rollers

Abstract—The results of friction-wear tests of rolled friction-polymer materials (FPM) of two types using the operating modes of the friction brake of a centrifugal type roller are presented in this work. The tests were performed on the Nanovea T50 tribometer according to the pin-on-disk scheme. Experimental dependences of temperature, coefficient of friction and wear on the pressure on the friction lining have been obtained. The stability of the coefficient of friction of the FPM/Steel friction pair was evaluated. Comparison and analysis of the results have been performed and recommendations on the application are presented.

Identification the Potential Causes of Stopline in Electrolytic Tinning Line Using Multi Attribute Failure Mode Analysis

PT. XYZ often suffers stopline in its production process of producing tin plate type coil in Electrolytic Tinning Line (ETL) machine which is used nonstop. The purpose of this research is identifying cause of stopline and determining the most potential cause of stopline using Multi Attribute Failure Mode Analysis (MAFMA). MAFMA itself is a combination method between FMEA and AHP. The result shows the causes of stopline are damaged bearing, broken shaft, not fitted construction, damaged rubber lining in sidewall, many tin particles in roll, torn roll, groove roll and bubble roll. The most potential cause is damaged bearing by weight of 0.172.

Analytical model and material equivalent methods for steady state heat partition coefficient between two contact discs in multi-disc clutch

The heat partition coefficient between two finite thickness contact discs during long-time sliding is studied with a coupled finite element method. Results show that the heat partition coefficient varies from its initial value to another steady state value rapidly instead of being a constant all the time. An analytical solution of the temperature field under invariant heat flux input is deduced, which tells that there exists a unique critical thickness ratio between the contact discs that keeps the heat partition coefficient a constant. An equivalent method for single-material contact bodies is proposed that is capable of calculating the steady state heat partition coefficient for any thickness ratio. It reveals that the steady state heat partition coefficient only has relationship with the mass density and the heat capacity of the materials and the thickness ratio. Based on this method, a two-step material equivalent method is further proposed for the contact discs that have friction linings on them. The solution shows that the steady state heat partition coefficient in this situation is also only determined by the material properties and the layer thicknesses. A test bench of multi-disc clutch is set up and a series of sliding experiments are conducted to validate the proposed equivalent methods and solutions of steady state heat partition coefficient. The measured experimental temperature variations show that the temperature level of the separator disc in the clutch is overestimated with the constant heat partition coefficient of semi-infinite model, while it is close to those calculated results with steady state heat partition coefficient. Therefore, the temperature fields of the contact discs during long-time sliding with constant speed can be figured out efficiently using the steady state heat partition coefficient with only small error, and these equivalent methods benefit the multi-disc clutch design and temperature estimation in practical applications.

CFD Analysis of the Sideslip Angle Effect around a BWB Type Configuration

In this study, we conducted numerical simulations for a nonslender BWB type planform with a rounded leading edge and span of 2.0 m to analyze the effect of the sideslip angle on the planform at a freestream velocity of 60 m/s. The Reynolds number based on the mean chord length was 2.9×106, and we considered the angle of attack ranging from -4° to 16° and sideslip angles up to 20°. We used an unstructured mesh with a prism layer for the boundary layer with 1.11×107 grid points, and the k−ω SST turbulence model. We analyzed force and moment coefficients with respect to variation of angle of attack and sideslip angles. Side force and rolling/yawing moment coefficients had highly nonlinear relationships with the sideslip angle while lift and drag coefficients were not significantly affected. We interpreted the mechanism of these aerodynamic characteristics based on pressure and skin friction contours. Suction pressure near the leading edge had a marked effect on the pitching and rolling moment. We identified five flow types on the blunt leading edge swept wing by skin friction lines and off-body streamlines at a high angle of attack and sideslip angles.

Investigation on wall shear stress measurement in supersonic flows with shock waves using shear-sensitive liquid crystal coating

Wall shear stress (skin friction) is one of the fundamental surface quantities in aerodynamics but its measurement remains challenging. This paper studies the measurement of wall shear stress vector fields in supersonic flows with shock waves using the shear-sensitive liquid crystal coating (SSLCC) technique. A previously developed SSLCC technique was improved and used for the measurement of wall shear stresses in a supersonic jet flow. Experimental results show that the flow structures including shock waves in the supersonic jet flow were visualized by the SSLCC technique; furthermore, the shear stress vector field over a planar surface induced by the supersonic jet flow was measured by the SSLCC technique. The shock waves and the compression-expansion repetitions in the supersonic jet flow were captured, respectively, by analysing the shear direction field and the skin friction line pattern. This work demonstrates the capabilities of the SSLCC technique to visualize and measure wall shear stresses in supersonic flows with complex shock waves.

Comparison of NMR and microwave NDE methods for defect detection in composite structures

Abstract New advanced non-destructive evaluation (NDE) methods such as nuclear magnetic resonance (NMR) imaging and microwave NDE methods are being developed for their advantages and high resolution for defect detection in composite structures. Glass/epoxy composite structures are being used for many applications in industry. Often, glass/epoxy composite structures are used along with rubber lining in oil and gas pipe industry. Rubber is adhesively bonded to composite inner surface to meet the requirements. The interface of glass/epoxy composite and rubber lining is critical. Any de-bond (separation of adhesively bonded liner from composite surface) at the interface may lead to failure of composite structure due to corrosive gases and liquids. The present paper reports application of proton single sided NMR method to evaluate the de-bonds of rubber liner with composite. Results are compared with microwave NDE technique which is an advanced non-contact inspection method. Results indicate application of both these techniques for evaluation of bonded interfaces. Advantages of both the techniques over conventional techniques have been discussed. De-bonds within rubber lining were also detected and correlated.

An assessment of the susceptibility of Becorit K-25SB and Modar R3/Mz friction linings

An assessment of the susceptibility of Becorit K-25SB and Modar R3/Mz friction linings

The effect of wollastonite silane-treatment on mechanical and tribological performance of NAO brake-pads

The current study aims to investigate the effect of silane-treatment of wollastonite on the mechanical, tribological performance of non-asbestos organic frictional brake-pad material. Two main friction lining specimens in the shape of brake-pads containing treated wollastonite (Wt) and untreated wollastonite (Wu) were produced to carry on the experiments. All produced samples were characterised and examined for their mechanical, chemical and tribological properties. The experimental results show that all parameters of tribological performance are within the acceptable standard range and that the tribological performance for all samples is almost the same in terms of friction coefficient and fade performance. Regarding wear, recovery performance and disc temperature rise (DTR), Wt samples offer better performance than Wu samples which was attributed to the good adhesion between wollastonite and the polymeric matrix after treatment. Moreover, scanning electron microscopy analysis is done on the tested samples and show overall improved surface of Wt than Wu. Finally, for full use of wollastonite silane-treatment advantages, it is recommended to be used in vehicles with less severe operating conditions such as motorbike and alike.

Abrasive fatigue wear rubber lining in the context of fractal analysis

Abrasive fatigue wear rubber lining in the context of fractal analysis

Managing corrosion in desalination plants

Abstract Environment quality, clean energy and worldwide water scarcity have been established today as central disciplines in modern science, engineering and technology. The innovative desalination technology of saline water (SW) contributes to alleviate these problems by producing fresh water from SW, mainly seawater and brackish water. Desalination plants (DPs) have a high level of corrosion risk as they handle and process aggressive SW under severe operating conditions, which include filtration, heat exchange, distillation, evaporation, agitation and circulation and high flow velocities, often turbulent. These SW, that is, sea, brackish and brines, cause localized corrosion such as pitting, crevice, galvanic and stress corrosion. In addition, biological fouling and mineral scaling are frequent nuisances that alter the equipment surface performance and induce corrosion. Two main technologies are used to obtain potable water and a brine for disposal: thermal evaporation and membrane separation, called reverse osmosis. The main way to minimize corrosion is the correct selection of corrosion-resistant materials for the fabrication of DP equipment, structures, installations and machinery. To protect the DP materials, industrial paints, polymeric coatings and rubber linings compatible with the DP fluids are applied. Cathodic protection with sacrificial anodic metals and/or impressed direct electrical current and corrosion inhibitors are supplied.

Rolling and slipping of droplets on superhydrophobic surfaces

The leaves of many plants are superhydrophobic, a property that may have evolved to clean the leaves by encouraging water droplets to bead up and roll off. Superhydrophobic surfaces can also exhibit reduced friction and liquids flowing over such surfaces have been found to slip in apparent violations of the classical no-slip boundary condition. Here we introduce slip into a model for rolling droplets on superhydrophobic surfaces and investigate under what conditions slip might be important for the steady state motion. In particular, we examine three limiting cases where dissipation in the rolling droplet is dominated by viscous dissipation, surface friction, or contact line friction. We find that in molecular dynamics simulations of droplets on ideal superhydrophobic surfaces with large effective slip lengths, contact line dissipation dominates droplet motion. However, on real leaves, droplet motion is likely to be dominated by viscous shear, and slip, for the most part, can be neglected.

Mobile Test Stand Validation for Measuring Friction Coefficient of Carrying Rope with Friction Lining

Abstract The article presents the problem of friction between the rope and the friction liner of a mining hoist very important for the safety of human transport. The friction linings approved for use in the Polish mining industry and their basic mechanical properties are presented. Laboratory and operational methods of friction feedback are described. This article presents an innovative mobile research stand developed at the Department of Mining Mechanization and Robotisation. The mobile test stand validation was presented.

Failure analysis of general stator and uniform wall thickness stator

Abstract Stator lining of positive displacement motor (PDM) is prone to generate thermal fatigue failure because of viscoelastic hysteresis of the rubber material. Based on the thermo-mechanical coupling modeling and rubber material testing, finite element method was used to study the effect of environment temperature and thermo-viscoelastic hysteresis to the lining thermal failure of general stator and uniform wall thickness stator. The results show that the deformation and temperature field of general rubber lining has been less affected by the environment temperature than thermo-viscoelastic hysteresis whose distribution of temperature field appears oval-shaped and the temperature gradient is large. Stator lining's temperature increases with the increasing of motor interference and well depth, and the rubber lining's thermal failure modes observed in practice are consistent with the calculation results. The temperature field distribution of uniform wall thickness rubber lining is relatively uniform, and the highest temperature and temperature rise are less affected by the motor interference and well depth, especially with small motor interference and in the shallow well. Therefore, the uniform wall thickness rubber lining has very obvious advantages in prolonging service life and improving the work performance of PDM.

The Investigation of Tribological Properties of Epoxy-Polyether Composite Materials for Using in the Friction Units of Means of Sea Transport

Abstract The tribological properties of composite materials with microdispersed proportions, based on the epoxy-polyether matrix, were investigated. The specimens were tested during dry friction and in the conditions of a corrosive environment. It was determined that at dry friction, the coefficient of friction is f = 0.33–0.35, and the contact temperature of the experimental specimen in the area of mechanical interaction of surfaces is T = 366–369 К. It was proved that composites, which were tested in the conditions of a corrosive environment, differ with improved antifriction properties and increased durability. In this case, the coefficient of friction is f = 0.08–0.09, and the contact temperature in the friction area is T = 295–298 К. It was stated that the wetting of the surface of the friction and heat removal from its area significantly affects the properties of the polymer during friction. In particular, the work surface of the source material and polymer, after testing in different conditions, was analyzed with the methods of optical and electron microscopy. The presence of lines of friction and microcracking of specimens at elevated temperatures was revealed. The elemental composition of the surfaces of materials in different areas was investigated with the help of X-ray microanalysis. The presence of selective transfer effect during the testing was ascertained as a result of analysis of the elemental composition.