Friction Lining Research Articles

Characteristics of pollutants emitted by motor vehicles and their impact on the environment and engine operation

Gaseous and solid pollutants (dusts) of atmospheric air have been defined. Dusts have been divided according to various criteria and their properties have been given. The sources and characteristics of anthropogenic and natural pollutants of atmospheric air have been presented. It has been shown that the main sources of anthropogenic pollutants, apart from industry, are motorization, and internal combustion engines of cars are a source of gaseous pollutants and solid particles, the emission of which has been significantly reduced. The originality of the article consists in conducting an extensive literature analysis and proving that the emission of "non-engine" pollutants in the form of dust from the wear of friction linings of brakes, clutches and from the wear of tires and roads, as well as mineral dust raised from the ground, is currently a greater threat to human health and the environment than engine emissions. The impact of particulate matter emissions from road transport and mineral dust, which is the basic component of road dust, on human health, vegetation and on the operation of engine and vehicle systems is presented.

Performance Evaluation for Positive Displacement Motors by Combining Fluid-Structure Interaction Simulations and Experiments

Summary The aim of this study is to propose a method for evaluating the performance of positive displacement motors (PDMs) from the perspective of robustness and energy conversion efficiency. Monitoring contact force and leakage is challenging when a steel rotor driven by liquid undergoes planetary motion within the rubber lining of the stator. A 3D model with a nominal diameter of 172 mm is established, along with a flow field of the same outer diameter as the stator. The constitutive parameters are determined according to the two-parameter Mooney-Rivlin model. After merging the overlapping nodes of the rubber lining and steel housing, the degrees of freedom are constrained from the exterior of the stator. Four-step loads are applied in ascending order. The average difference in overall efficiency between the experimental results and the simulation of the same model PDM is 1.58%. The sequential simulations include three sets of nine variables: lead (800 mm, 914.4 mm, 1200 mm), interference fit (0.1 mm, 0.2 mm, 0.3 mm), and rubber hardness (70 HA, 80 HA, 85 HA). Contact force differentials on each sealing band are calculated before and after stable operation. The reliability and stability of the cavities are assessed using the mean and variance of the force differentials. Efficiencies after each load stabilization are calculated to compare performance. For loads other than 200 N·m, the overall efficiency of the PDM with the optimized parameter combination increased by 2.98%, 0.27%, and 2.32%, respectively. Finally, this parameter combination is applied to a curved profile PDM. For loads other than 200 N·m, the overall efficiency increased by 3.22%, 0.89%, and 5.14%. This method, which combines the fluid-structure interaction (FSI) with an analysis of robustness and efficiencies, can be used to analyze the strengths and weaknesses of different parameter PDMs and to assess the performance of different profile motors.

Dynamic Monitoring the Friction Transmission of Mine Hoist Using Triboelectric Nanogenerators Self‐Powered Sensor Based on Different Surface Structures Embedded in the Friction Lining

The friction lining is a critical component of the friction hoist, serving as the driving force for lifting through its interaction with the wire rope. Monitoring the friction state between the wire rope and the friction lining is crucial as it directly impacts lifting capacity, work efficiency, and overall safety. By employing finite element simulation and creating surface microstructures on triboelectric nanogenerators (TENG) using ultraviolet laser, this study demonstrats that microstructure can improve voltage output. Compared with TENG without morphology, the voltage is increased by nearly seven times, reaching 2.28 V. Moreover, experiments revealed that embedding TENG at the optimal standard point of the friction lining enables effective monitoring of friction transmission under varied conditions, with the voltage signal showing synchronization with friction force. Notably, the voltage reached 520 mV under increasing specific pressures and stabilized around 670 mV with rising sliding speeds. This research represents a significant step toward real‐time monitoring of intelligent mining systems by dynamically observing friction transmission in mine hoists.

Clamping Force Control of Electromechanical Brake Actuator Considering Contact Point between Friction Lining and Brake Disc

Currently, most electromechanical brake (EMB) schemes are only suitable for passenger cars, and their maximum clamping force is insufficient to satisfy the braking demands of commercial vehicles. Additionally, previous studies on clamping force control are largely based on an EMB equipped with sensors. Due to constraints in installation space and cost, sensorless EMBs are gradually gaining attention. Furthermore, accurately identifying the contact point between the friction lining and the brake disc is the promise of clamping force control for sensorless EMBs. Hence, a sensorless EMB scheme suitable for commercial vehicles is proposed in this study. Secondly, a dynamics model of the EMB actuator is established. After a comprehensive analysis of the proposed EMB actuator, a clamping force control strategy considering the contact points between the friction lining and the brake disc is proposed. Finally, simulation analyses of the strategy are carried out. The results show that the axial length of the proposed EMB actuator is shortened by 17.6% compared with a mainstream pneumatic disc brake. Furthermore, the proposed method can accurately identify the contact points between the friction lining and the brake disc, and the proposed control strategy enables the EMB actuator to achieve the fast response, accurate tracking, and stable maintenance of the target clamping force.

Research on the Design of Multi-Rope Friction Hoisting System of Vertical Shaft Gravity Energy Storage System

Renewable energy generation methods such as wind power and photovoltaic power have problems of randomness, intermittency, and volatility. Gravity energy storage technology can realize the stable and controllable conversion of gravity potential energy and electric energy by lifting and lowering heavy loads. The hoisting system is an important component of a gravity energy storage system, and its lifting capacity and speed seriously restrict its energy storage capacity, energy conversion efficiency, and operational safety and reliability. In this paper, a design method for a multi-rope friction hoisting system of a vertical shaft gravity energy storage system is proposed. The parameter design and calculation of the hoisting rope, balance rope, and friction wheel of the friction hoisting system under typical conditions were carried out. The static and dynamic anti-slip capabilities of the friction hoisting system under the typical condition were explored. The results show that the maximum acceleration and deceleration speed of the compacted strand wire rope scheme is the largest, and the lifting and lowering time is the shortest. The maximum acceleration and deceleration speed of the triangular strand wire rope scheme is the lowest, and the lifting and lowering time is the longest. The dynamic tension of the hoisting rope at the heavy-load end is positively correlated with the acceleration, and the maximum value occurs in the accelerated lifting stage and decelerated lowering stage of the heavy load. The static anti-slip safety factor between the hoisting rope and the friction lining and the specific pressure between the hoisting rope and the friction lining comply with the requirements of China’s Safety Regulations for Coal Mines. The dynamic anti-slip safety factor of the hoisting system under different rope selection schemes is greater than the minimum value of 1.25 stipulated in the Safety Regulations for Metal and Nonmetal Mines. The research results are of great significance for the safety, reliability, and stable and efficient energy storage of a gravity energy storage system.

Fast Gradient Algorithm with Dry-like Friction and Nonmonotone Line Search for Nonconvex Optimization Problems

Fast Gradient Algorithm with Dry-like Friction and Nonmonotone Line Search for Nonconvex Optimization Problems

Patterns and correlates in the distribution, design and management of garden ponds along an urban–rural gradient

Urbanisation results in the loss and alteration of natural wetlands and ponds. However, garden ponds in cities and towns can potentially act as rich reservoirs of aquatic biodiversity and stepping stones for dispersal. Homeowners with a range of different motivations, including biodiversity values, install garden ponds. Here, our main aim was to study whether the design and management choices of garden pond owners depended on the location of ponds (capital city vs. countryside), when ponds were installed (pond age), or whether fish were introduced. We surveyed 834 garden pond owners across Hungary using a citizen science questionnaire, asking questions on pond size, location, construction date and materials, vegetation structure, introduction of fish and management practices. From 753 validated responses, we found that the introduction of fish into ponds and high urbanisation were strongly associated with local features and management practices, especially large ponds with a water circulation feature, irrespective of pond age. A typical garden pond in Hungary is ~ 20 m2, < 10 years old, made of rubber lining, contains fish, aquatic vegetation and circulating water, and is actively managed. There was a spatial separation of ponds based on local features between ponds in the capital city (Budapest) and elsewhere. These findings suggest that garden pond owners in the city were more likely to make different choices in pond design and management compared to owners in regional areas. Our results also suggest that pond owners may primarily select management practices to improve habitat quality for ornamental fish. Our findings have important implications for maintaining aquatic biodiversity in urban areas, where garden ponds may be the only aquatic habitat available.

REGENERATIVE BRAKING WITH POWER MONITORING IN ELECTRIC VEHICLES

The duration of battery charging and the scarcity of charging stations are the main obstacles to the widespread usage of electric vehicles. We thus suggest a regenerative breaking system here. Every time the brakes are applied, a car might produce energy thanks to this mechanism. More power is produced with stronger brakes. In a braking drum, we employ a friction lining arrangement. The friction liner on a rotating drum does not wear down the drum. When the brakes are applied, the friction lining within the drum touches it, moving the motors attached to it in the same direction. This process uses the motors as a dynamo to produce electricity. This method so provides a regenerative braking system by enabling the automobile battery to be charged each time the brakes are used. It affects us both in different ways.

Research on the Influence of Biomimetic Patterns Surface on the Surface Temperature of Drum Brake Lining

Vehicles need to brake frequently on long downhill sections. In this case, the surface of the friction lining is prone to accumulating a large amount of heat, which will reduce the performance of the braking material and lead to braking failure. This article analyzes the heat generation and dissipation mechanism during the braking process of drum brakes based on the law of energy conservation, and establishes a thermal conductivity differential equation. Subsequently, with the honeycomb texture as the biomimetic target, circular, square, and honeycomb patterns with different parameters were designed on the surface of the friction lining, and a finite element model was established using Ansys Workbench. Thermodynamic coupling analysis shows that patterned friction lining can reduce the maximum temperature of the braking surface. Honeycomb patterns have better heat dissipation effects than circular and square patterns. Compared with non patterned brake pads, honeycomb patterns can reduce the maximum surface temperature of brake pads by 14.6%. When the surface area ratio of the honeycomb is 56.8%, its heat dissipation effect is the best.

Investigation of the friction and deformation behaviour of high-speed brakes

Spring-applied brakes are widely used components in industrial drive systems. They provide a braking torque by friction between a mostly organic friction lining and a metallic counter surface. Increasing with decreasing size, they currently achieve speeds of up to 6,000 rpm, which corresponds to a sliding speed in frictional contact of up to 35 m/s. At the same time, there is a trend towards high-speed drives, with speeds of 10,000 rpm and above. So far, little is known about the behaviour of the friction value and torque of conventional spring-applied brakes with low-cost organic friction linings under these operating conditions. For this reason, a test rig was develop - ed that allows testing at sliding speeds of up to 120 m/s with different load inertias. The tests carried out at KAt so far showed that with limited friction work, the conventional spring-applied brake reaches the nominal braking torque at higher sliding speeds. In addition to thermal overload of the friction lining, plastic deformation of the friction bodies can also permanently disrupt the operating behaviour of brakes operated at high sliding speeds. The plastic deformation of the friction discs manifests itself, for example, in a saucer-like shape of the discafs, leading to a reduction in the air gap and causing unwanted changes in the friction conditions. This paper describes the relationship between friction work and friction coefficient in organic linings and the physical mechanism of the deformation process of the friction discs. Based on these possible measures to reduce deformation are explained.

Investigating Failure Modes and Performance Impacts of Wet Clutches in Automotive Limited Slip Differentials

In the design of rear-axle locking differentials, the desired high locking effect is often achieved using wet multi-plate clutches. This study conducts an in-depth investigation into the spontaneous damage behavior of these clutches through a series of methodical experimental tests. It focuses on three different clutch variants, each equipped with organic friction linings—namely, paper-based, carbon composite, and woven carbon—and undertakes a comparative analysis of their respective damage typologies. The experimental analysis identifies and characterizes patterns of damage, notably the buckling of steel plates and the detachment of lining. Moreover, the study thoroughly examines and compares the friction and temperature behavior under the high load conditions applied to these three friction systems. Concurrent temperature measurements enable the establishment of robust temperature-based criteria for predicting and understanding damage behavior.

Оцінка ресурсу фрикційних поверхонь гальмівних дискових механізмів за показниками відносного зношення для легкових автомобілів

Modern development of vehicle designs requires paying great attention to braking properties, which will depend on the design parameters of the brake mechanisms. The article discusses a scheme where a disc brake is installed on the front wheels, and drum brakes are installed on the rear wheels. From the diagram of the distribution of forces that act on the vehicle during braking, the maximum friction forces for the front and rear axles were determined. A general formula was obtained for the braking distance of a vehicle, during which wear of the brake mechanism occurs. We used the results of the well-known theory of friction and wear by I.V. Kragelsky. The mathematical wear model was built for each friction pair. The wear model takes into account the design parameters of the vehicle, the wear resistance coefficient of materials, the initial braking speed of the vehicle, the mileage and braking distance. The main design parameters of the brake system are the friction radius, the kinematic rolling radius of the wheel, and the amount of drive pressure.&#x0D; To assess the service life of the brake mechanism, it was proposed to use such an indicator as the relative wear of associated parts. A formula has been obtained for calculating this indicator based on changes in geometric parameters and operating modes of the brake mechanism under operating conditions. A forecast was made of the service life of the brake mechanisms of the front and rear axles of passenger cars, which is proposed to be carried out according to the indicator of relative wear of friction surfaces. Graphic dependences of the distribution of relative wear of the friction surfaces of brake mechanisms for Chevrolet Aveo and Forza cars were constructed. It was shown using the example of Chevrolet Aveo passenger cars that the relative wear of the front axle brakes is maximum and it varies from 22.5 to 26.1%, and for the rear axle this figure varies from 21.0 to 22.5%. The service life of the brake disc is 4.44 times greater than the service life of the friction lining for the Chevrolet Aveo. For the Forza car this figure is 4.76. The results of the work can be used to estimate the residual life of brake mechanisms, taking into account operating conditions.

Developing the method ensuring stable braking via advanced design of braking devices

The aim is to develop a method for ensuring the stability and efficiency of the braking process by differentiating the friction linings of brake pads of pad-type disc braking mechanisms. The research applied differentiation of the interaction time of friction pairs and their area, which provides the highest stability indicators of braking mechanisms. The non-standardized bench equipment developed by the author, as well as segmental braking mechanisms providing differentiation of friction pairs by area were used in the study. A method of designing the resultant braking torque was developed using the relationship between the transverse movement of the pads and the developed braking torque of the friction unit. As a result of bench tests, the stability and fluctuation coefficients of the braking torque of the developed pad-type disc brake mechanisms with six pressing elements increased by 12.2 and 34.9%. These values were obtained as compared to serial brake mechanisms equipped with a monopressing mechanism with a single brake pad. The discrepancies between the simulated and obtained data during the bench test on the stability criteria averaged 5.1 and 6.7% for the stability coefficients and braking torque fluctuations for the three brake mechanism variants under consideration, respectively. Differentiation of pressing elements and segmentation of brake pads has the effect of increasing the stability criteria and braking efficiency for pad-type disc brakes. With the analysis of the dependence of the transverse displacement and the developed braking torque, a guaranteed result on the stability criterion and braking torque fluctuations of pad-type disc brakes was modeled. Based on the conducted bench tests, the model developed for obtaining the resultant braking torque for the braking mechanism with segmental pads can be used for designing friction pairs with the set parameters.

Redesign of a Disc-on-Disc Computer Numerical Control Tribometer for a Wide-Range and Shudder-Resistant Operation

The paper presents a redesign of the custom disc-on-disc-type tribometer intended for the experimental characterization of the friction and wear of automotive dry clutch friction lining. The redesign is aimed at expanding the operating range at which the machine is not sensitive to shudder vibrations. This is achieved through a set of hardware and software upgrade measures. First, the natural frequency of the normal load-generation linear axis of the machine is increased by enlarging its bending stiffness and reducing the suspended mass. The former is realized by replacing the single, two-axial force/torque piezoelectric sensor with a set of three three-axial piezoelectric force sensors, adding a set of stiff linear guides, and reducing the lengths of the cantilevers of lateral forces acting on the linear axis guide system. The latter is accomplished by reducing the overall dimensions of the cooling disc and redesigning the thermal insulation components. The shudder sensitivity resistance is further reduced through individual normal force-readings-based adjustment of parallelism between friction contact surfaces and the increase in the stiffness of eccentrically positioned water-cooling pipes. Finally, the stability of the coefficient of friction and, consequently, the wear process are boosted by adjusting the control routines to minimize the circumferential and/or radial temperature gradients. These adjustments include the introduction of a clutch lock-up interval at the end of the clutch closing cycle, a minimum cooling delay inserted between two closing cycles, and maximum normal force demand of the clutch torque controller. The performance gain of the upgraded tribometer is demonstrated through a study of the dry clutch friction plate static wear experimental characterization for a wide range of operating conditions.

Study on the surface microtexture microscopic friction and wear characteristics of 304 stainless steel

In order to reveal the friction behaviour and wear mechanism of nanoscale textures on the friction pair of 304 stainless steel, molecular dynamics simulations were firstly used to investigate the effects of smooth and textured surfaces on the tribological properties of the stainless steel substrate, and then focus on the effects of sliding velocity and depth on the surface morphology, mechanical force, friction coefficient, anisotropy, stress, temperature and dislocations of the textured substrate. The results show that the temperature, friction, stress, and dislocation line length of the textured surface are relatively smaller than those of the non-textured surface, and the textured surface has a smaller and more stable friction factor, which ultimately leads to a reduction of the friction factor by about 0.090. When the sliding distance is 120 Å, the number of defective atoms in the textured substrate is reduced by 12.9%, and its anisotropy is more stable. At the same indentation depth, the average friction coefficient, temperature and anisotropy increase significantly with increasing sliding velocity. The average friction coefficient is maximum when the sliding velocity is increased to 400 m s−1, with a value of about 0.833. The sliding friction, friction coefficient, dislocation line length, number of defect atoms, number of stacked atoms, stress, temperature and anisotropy factor increase with increasing depth of abrasive indentation. The average friction coefficient is minimum at a sliding depth of 4 Å, with a value of about 0.556, and the number of defective atoms is reduced by 83.2%. This indicates that textured surface treatment of 304 stainless steel and selection of appropriate sliding parameters can effectively reduce the wear during the friction process and improve the wear resistance of the substrate.

An Optimization Study on a Novel Mechanical Rubber Tree Tapping Mechanism and Technology

All-natural rubber is harvested from rubber trees (Hevea brasiliensis Muell. Arg.) by traditional tapping knives, so rubber tapping still heavily relies on labor. Therefore, this study explored a novel, hand-held mechanical rubber tapping machine for rubber tree harvesting. In this study, a mechanical tapping cutter with a vertical blade and adjustable guide was first described. The response surface method was applied to evaluate factors affecting the tapping effect. The experimental values were in close agreement with the predicted value. Machine-tapped latex was comparable in quality to hand-tapped latex. Based on the single-factor results, the response surface method (RSM) and the center combined rotation design (CCRD) optimization method were adopted to explore the influence of three factors influencing vertical blade height (A), cutting force (B), and spiral angle (C) on the tapping effect. Regarding the cutting rate of the old rubber line (Y1), cutting time (Y2), latex flow rate (Y3), and average cutting current (Y4) as evaluation indexes of the tapping effect, an optimization scheme was determined. The quadratic model fits for all the responses. The test results showed that the main factors affecting Y1, Y2, Y3, and Y4 were A and B, B, A and C, and B, respectively. Under optimal conditions, the influencing factors of A, B, and C were 10.24 mm, 51.67 N, and 24.77°, respectively, when the evaluation index values of Y1, Y2, Y3, and Y4 were 98%, 8.65 mL/5 min, 9.00 s, and 1.16 A. The range of the relative error between the experimental and predicted results was from −11.11% to 11.11%. According to the optimized treatment scheme, a comparison test was designed between mechanical and manual rubber tapping tools. To verify the availability and effect of the mechanical tapping method preliminarily, the important rubber tapping evaluation indexes included bark thickness, bark excision, latex flow time, cutting time, ash content, and cutting depth, which were selected to serve as a comparison test. There was no significant difference between hand and mechanical methods, except ash content (p &lt; 0.05) and cutting time (p &lt; 0.01). The mechanical tapping machine proposed in this study is meaningful to improve cutting efficiency, practicality, and operability. Furthermore, it provides crucial theoretical references for the development of intelligent tapping machines.

IMPROVING THE ORGANIZATION OF CENTRALIZED RESTORATION OF AGRICULTURAL EQUIPMENT PARTS

Effective use of machines largely depends on timely and high-quality maintenance and repair. Due to the increase in the volume of restoration of units and aggregates at specialized enterprises, an opportunity was created in the workshops of farms and collective farms to more widely apply the aggregate method of restoration and repair. Improving the organization of centralized restoration of damaged parts makes it possible to restore tens of millions hryvnas worth of parts in a year. The organization of centralized delivery of material and technical means to farms is applied using the services of equipping farms with the necessary equipment in assembled, adjusted and run-in form. Increasing the level of concentration of repair production, deepening its specialization will allow to significantly improve the quality of repair, to bring the resource of repaired machines, tractors, combines and aggregates up to 80%. Before repairing driven discs of clutches of tractors, cars, combines, to replace friction linings, it is necessary to carry out operations of drilling, riveting and knocking off old linings. These operations require a lot of labor and the use of additional tools, which leads to significant capital investments. The paper proposes a device for cutting the fastenings of the friction linings of the driven clutch discs. Taking into account the conditions of agricultural enterprises, which have repair workshops, and the presence of vertical boring and milling machines, it is proposed to organize their use for the operation of removing worn friction linings. For riveting of friction linings of driven clutch discs, the development of a hydraulic stand is proposed, which can be made from standard units in the workshops of agricultural enterprises. Using this stand will make it possible to increase labor productivity when performing this operation and reduce its time.

Evaluation of the tribological behavior of a brake disc-pad friction pair using a fuzzy inference model based on an adaptive network (ANFIS)

The purpose of this research is to forecast the tribological behavior of the materials used in the field of braking systems using an Artificial Neural Network (ANN) based on the experimental data obtained by measuring the friction between the friction linings and the brake disc of a bicycle in the translational movement. The data analysis results from this research show that the estimates and forecasts with the proposed model (ANFIS) of the dynamic friction coefficient (COF) between the pads and the disc in translational motion using the ANN have been confirmed to be powerful and useful. The experimentally determined average value of the dynamic COF was 0.2003 with a standard deviation of 0.0233 in the range of values of 0.1244-0.3013.

Numerical and experimental analysis of the heat transfer process in a railway disc brake tested on a dynamometer stand

Abstract The effectiveness of railway brakes is highly dependent on the thermal condition of the brake disc and friction linings. An effective research method for the heat transfer process in brakes was computer simulation and experimental tests on a full-size dynamometric test bench. A two-dimensional, axially symmetric numerical model of transient thermal conductivity in a railway brake was presented. Appropriate boundary conditions of the problem were applied, describing the heat generated in the brake and discharged to the environment. The problem was solved using the finite-element method. This article presents exemplary results of the brake temperature calculations obtained using the numerical model and the results of experimental tests carried out on two types of brake discs.

Interdependence of constructive and operation parameters of brake friction units

Problem. Theoretical and experimental studies of the relationship between the braking torques developed by the friction assemblies of various types of brakes and their design and operational parameters made it possible to establish the following: the values of the braking torques developed by the friction assemblies of various types of braking devices and the influence of design parameters on them; changing the gradients of the braking moments for the most loaded friction pairs of the belt-pad brake of the drilling winch; values of local temperature gradients at the beginning and at the end of braking of vehicles and drilling winches to determine the thermal stresses in the metal friction element. Goal. The purpose of the work is to establish the relationship between the braking torques developed by the friction brake assemblies and their design and operational parameters. Methodology. The solution to the tasks is that the design is based on the principle, according to which, if possible, massive elements that interfere with the free expansion of less massive heated areas are excluded. Results. The relationship between the design parameters of various types of brakes and their operational parameters is established. Originality. It was determined that the design and operational parameters of the brakes depend on the density of the heat flow that penetrates the rims of the pulley and the drum, as well as the body of the disc. O. I. Volchenko proposed three theorems to establish the regularities of heating and cooling of isotropic metal friction elements with compliance with the initial and boundary conditions for metal-polymer friction pairs of brakes. Practical value. The use of a new operating parameter, which is the gradient of braking moments developed by friction pairs "brake pulley - friction lining", allows to estimate their values for each friction lining of the brake belt.