Friction Coefficient Test Research Articles

Enhancement of Microwave Heating Technology for Emulsified Asphalt Mixtures Using SiC-Fe3O4 Composite Material.

The application of microwave heating technology can significantly enhance the water evaporation rate of emulsified asphalt mixtures post paving. To improve the microwave absorption and curing performance of these mixtures, SiC-Fe3O4 composite material (SF) was incorporated. This addition aims to enhance the microwave absorption efficiency and accelerate the curing process of emulsified asphalt mixtures under microwave heating. This study begins with an analysis of the microwave absorption principles pertinent to emulsified asphalt mixtures. Subsequently, the microwave heating temperature fields of ordinary emulsified asphalt mixture (EAM), SiC emulsified asphalt mixture (S-EAM), Fe3O4 emulsified asphalt mixture (F-EAM), and SiC-Fe3O4 emulsified asphalt mixture (SF-EAM) were simulated using COMSOL Multiphysics finite element software (COMSOL 6.2). The early strength variations in SF-EAM under different microwave heating durations were then examined through adhesion tests, leading to the proposal of a microwave heat curing process for SF-EAM. Finally, the wear resistance, water damage resistance, rutting resistance, and skid resistance of SF-EAM post-microwave curing were evaluated through wet wheel wear tests, wheel track deformation tests, and road friction coefficient tests. The results indicate that the optimal microwave heating time is 90 s, with the microwave absorption performance of the materials ranked as follows: EAM, S-EAM, F-EAM, and SF-EAM, from lowest to highest. The road performance of SF-EAM complies with specification requirements, and its wear resistance, water damage resistance, and rutting resistance are notably improved after microwave heating.

Development of sinter linings for high-speed trains

Abstract In this study, brake linings with Cu (copper)-based and Cu-10Sn (bronze)-based matrix structures have been developed and produced by the powder metallurgy method using sinter metal technology for use in high-speed trains. The developed linings were compared with commercial high-speed train linings. Firstly, the mixing process was carried out in a Turbulo 3V three-dimensional mixer for 4.5 h at 50 rpm. The pressing process was performed at room temperature, under the pressure of 350–450 MPa, and the sintering temperature for Cu-based linings was 1,000 °C, while for Cu-10Sn-based linings, it was 800 °C. After the pressing and sintering processes, lining sample density calculations were conducted, and hardness tests were carried out in the Rockwell L scale. Shear strength tests, friction coefficient, and wear tests were conducted according to SAE J 661 standards. It was observed that sinter metal brake linings with Cu and Cu-10Sn main matrix structures showed similar properties and met the technical requirements. It was determined that the developed production prescriptions are promising for industrial production and patent studies.

Comparing an Integrated Amphiphilic Surfactant to Traditional Hydrophilic Coatings for the Reduction of Catheter-Associated Urethral Microtrauma.

Hydrophilic-coated intermittent catheters have improved the experience of intermittent urinary catheterization for patients compared to conventional gel-lubricated uncoated catheters. However, the incorporation of polyvinylpyrrolidone (PVP) within hydrophilic coatings can lead to significant issues with coating dry-out. Consequently, increased force on catheter withdrawal may cause complications, including urethral microtrauma and pain. Standard methods of evaluating catheter lubricity lack physiological relevance and an understanding of the surface interaction with the urethra. The tribological performance and urethral interaction of commercially available hydrophilic PVP-coated catheters and a coating-free integrated amphiphilic surfactant (IAS) catheter were evaluated by using a biomimetic urethral model designed from a modified coefficient of friction (CoF) assay. T24 human urothelial cells were cultured on customized silicone sheets as an alternate countersurface for CoF testing. Hydrophilic PVP-coated and coating-free IAS catheters were hydrated and the CoF obtained immediately following hydration, or after 2 min, mimicking in vivo indwell time for urine drainage. The model was observed for urethral epithelial cell damage postcatheterization. The majority of hydrophilic PVP-coated catheters caused significantly greater removal of cells from the monolayer after 2 min indwell time, compared to the IAS catheter. Hydrophilic PVP-coated catheters were shown to cause more cell damage than the coating-free IAS catheter. A biomimetic urethral model provides a more physiologically relevant model for understanding the factors that govern the frictional interface between a catheter surface and urethral tissue. From these findings, the use of coating-free IAS catheters instead of hydrophilic PVP-coated catheters may help reduce urethral microtrauma experienced during catheter withdrawal from the bladder, which may lead to a lower risk of infection.

Investigation of the Corrosion and Tribological Properties of WC-Co Tools Hardened with PVD Coatings in Solid Oak Wood Processing

Corrosion and friction coefficient tests were performed on solid oak wood machined with hard-metal woodworking tools coated with PVD coatings (AlCrN, AlTiN, TiAlN, TiCN and CrN). The tannic acid attacks the carbide more intensively than the PVD coatings. During cutting, corrosion spreads on the cutting edge of the cutter due to mechanical action, which dissolves the cobalt binder of the hard-metal and causes the carbide grains to flake off. After 80 min of contact with the wood, the cobalt content decreases from 3.53 to 1.74%. Depending on the PVD coating material, cracks of 4 to 40 µm in width appear after 120 min (9000 m cutting path). After 120 min of machining, wear, corrosion effects and the influence of corrosion on the coefficients of friction were evaluated for tools with and without PVD coatings. TiCN is the most sensitive to corrosion, while AlCrN and CrN coatings are the least sensitive, with the AlTiN coating being the most affected under real cutting conditions (with mechanical + thermal + corrosion effects) and the tools with CrN and AlCrN coatings being the least affected. Corrosion affects the hard-metal and PVD coatings and reduces the coefficient of friction. The angle between the directions of sliding and sharpening of the cutting edge sharpening significantly influences this parameter. The coefficient of friction of hard-metal WC-Co and PVD coatings is higher in the parallel machining direction than in the perpendicular machining direction and ranges from 16.03% (WC-Co) to 44.8% (AlTiN). The coefficient of friction of hard-metal WC-Co decreases by 5.13% before and after exposure to tannic acid, while the corrosion of PVD coatings reduces it by 4.13% (CrN) to 26.7% (TiAlN).

Friction Characteristics and Lubrication Properties of Spherical Hinge Structure of Swivel Bridge

A spherical hinge structure is a key swivel bridge element that must be considered when evaluating friction characteristics and lubrication properties to meet the rotation requirement. Polytetrafluoroethylene (PTFE)-based spherical hinge sliders and lubrication coating have been employed for over 20 years, but with the growing tonnage of swivel bridge construction, their capacity to accommodate the required lubrication properties can be exceeded. In this manuscript, the optimal friction coefficient of the spherical hinge is obtained through the finite element analysis method. Four lubrication coatings and four spherical hinge sliders are prepared and tested through a self-developed rotation friction coefficient test, four-ball machine test, dynamic shear rheological test, and compression and shear performance test to evaluate the lubrication and friction properties of the spherical hinge structure. The results of the finite element analysis show that the optimum rotation friction coefficient of the spherical hinge structure is 0.031–1.131. The test results illustrate that the friction coefficient, wear scar diameter, maximum non-seize load, phase transition point, and thixotropic ring area of graphene lubrication coating are 0.065, 0.79 mm, 426 N, 14.6%, and 64,878 Pa/s. The graphene lubrication coating has different degrees of improvement compared with conventional polytetrafluoroethylene lubrication coating, showing more excellent lubrication properties, bearing capacity, thixotropy, and structural strength. Compressive and shear tests demonstrate that polyether ether ketone (PEEK) has good compressive and shear mechanical properties. The maximum compressive stress of PEEK is 87.7% higher than conventional PTFE, and the shear strength of PEEK is 6.07 times higher than that of PTFE. The research results can provide significantly greater wear resistance and a lower friction coefficient of the spherical hinge structure, leading to lower traction energy consumption and ensuring smooth and precise bridge rotation.

Synthesis of Al2O3@MnO2 composite abrasives and their chemical mechanical polishing performance on silicon carbide (SiC)

The effectiveness of silicon carbide (SiC) planarization mostly relies on the chemical and mechanical effects during chemical mechanical polishing (CMP). Nevertheless, the alumina (Al2O3) abrasive only provides a mechanical effect and is incapable of achieving a high-efficiency polishing of SiC. To address this issue, a series of novel Al2O3@MnO2 composite abrasives were prepared by encapsulating varying amounts of manganese dioxide (MnO2) on Al2O3 abrasive, and the polishing performance on SiC wafers was evaluated. The X-ray diffraction (XRD) and scanning electron microscope (SEM) images, along with the size and zeta potential data, show that MnO2 is successfully coated on the surface of Al2O3, and the dispersion of Al2O3@MnO2 composite abrasive is significantly improved when compared with the pure Al2O3. Furthermore, the CMP experiment and surface profile analysis demonstrate that the material removal rate (MRR) can reach a maximum value of 640.47 nm/h when using a 0.05 wt% MnO2-coated Al2O3 composite abrasive, which is 76 % higher than that of traditional Al2O3 abrasive. Furthermore, the average surface roughness (Sa, arithmetic mean height) of SiC is reduced to 0.73 nm. X-ray photoelectron spectroscopy results reveal that the surface of SiC is oxidized and forms a chemical bond known as Mn–O–Si after CMP. The results of the friction coefficient test and contact angle test indicate that slurries containing composite abrasive have exceptional wettability and a higher friction coefficient. Under the synergistic chemical and mechanical effects, SiC is oxidized to soft oxide and then removed circularly to reach excellent flatness.

Recent Progress on Anti-Slip and Highly Wear-Resistant Elastic Coatings: An Overview

There has been great interest in the research and development of different anti-skid and highly wear-resistant materials that can effectively reduce energy losses and improve efficiency in numerous applications. This article reviews the design, performance, and application of anti-skid and highly wear-resistant coating materials at home and abroad. First, it introduces the structure and mechanism of anti-skid and wear-resistant coatings. The preparation of different anti-slip coatings is mainly accomplished by changing the base material and anti-slip granules as well as the coating method, and the anti-slip performance is determined with the coefficient of friction test. The application mostly encompasses airplane and ocean decks, as well as pedestrian spaces. This review introduces the development status and research progress of metal-based anti-skid coatings and polymer-based anti-skid coatings, which are two groups of pavement. Finally, the challenges and future development directions of this key field are summarized and considered.

Influence of basalt fiber on performance of thin overlayer asphalt mixtures based on multiple experimental methods

Because of the fast deterioration speed of the surface function of conventional asphalt pavement, thin overlayer with many advantages has been applied to the pavement surface. However, due to problems such as insufficient stripping resistance and cracking resistance, the performance of the thin overlayer needs to be further improved. To achieve this target, basalt fiber was introduced into two types of thin overlayer asphalt mixtures (Open graded friction course, OGFC-5, and Stone matrix asphalt mixture, SMA-5). The wheel tracking test and uniaxial penetration test for high temperature deformation resistance, low temperature bending beam test and indirect tensile asphalt (IDEAL) cracking test for cracking resistance, cantabro test for stripping resistance, and friction coefficient test for skid resistance were conducted to evaluate various performance of thin overlayer asphalt mixtures, along with the dynamic modulus test for dynamic mechanical response. The results showed that adding basalt fiber could enhance the high temperature deformation resistance, low temperature cracking resistance, intermediate temperature cracking resistance and stripping resistance of the thin overlayer, while having no significant impact on skid resistance. Furthermore, adding basalt fiber could increase the modulus in the high temperature region and decrease the modulus in the low temperature region of the thin overlayer asphalt mixtures, indicating thin overlayer with basalt fiber presenting superior both high temperature and low temperature performance. In addition, the evaluation indexes of SLT and SHT proposed from dynamic modulus test exhibited good consistency with the results of the performance tests.

Effect of EDTA-modified alumina composite abrasive on the CMP performance of sapphire substrate

Sapphire is one of the most widely used substrate materials for semiconductor lighting. With the improvement of chemical mechanical polishing (CMP) processing technology for sapphire substrate, mass production, and cost control requires faster polishing efficiency and better surface quality. In CMP, alumina abrasive is widely used for its high polishing rate, but it also has the disadvantages of easy agglomeration and poor polishing quality. Therefore, ethylenediamine tetraacetic acid (EDTA)-grafted alumina composite abrasives were produced by a two-step process for the sapphire substrate CMP. As demonstrated by time of flight secondary ion mass spectrometry and fourier transform infrared spectroscopy, EDTA has been successfully grafted onto the surface of alumina particles. As shown by the scanning electron microscope, particle size distribution, and zeta potential analyses, the modified alumina composite abrasives exhibit superior dispersion properties than pure alumina particles. CMP experiment results show that the material removal rate (MRR) of the alumina composite abrasives can reach up to 2.6 μm/h, and the surface roughness (Sa) of the sapphire substrate can be reduced to 0.89 nm, which is 53 % higher and 66 % lower than pure alumina, respectively. According to X-ray photoelectron spectroscopy, the chemical etch of modified abrasive particles was strengthened, and the complex reaction occurred throughout the CMP process to generate the C–O–Al structural compound. Meanwhile, the friction coefficient test and contact angle test were combined to create the contact wear model. It shows that the addition of EDTA expands the contact area between the composite abrasives and the surface of substrates, improving the mechanical interaction during CMP. The chemical reaction and mechanical action combine and promote each other to enhance the CMP performance.

The effect of huntite and barite mineral-based polymer composite brake materials on friction and braking performance

Mineral materials are used in brake pad polymer composites at different rates, and positive results are obtained in tests conducted with the brake pads produced. This study produced brake pad polymer composites based on huntite and barite minerals. The materials forming the samples were mixed in a kinetic-type mixer, pressed using the hot molding method and prepared for the experiments with the curing process as the final process. Density, friction coefficient, wear rate and TG-DSC mass loss tests were performed on the samples. After the friction coefficient test, microscopic analyses of the brake pad samples were performed using a scanning electron microscope, and the surface roughness was measured using a three-dimensional profilometer. In the friction coefficient, hardness and mass loss analyses, values similar to those reported in the literature were obtained for all the samples. As a result, it was determined that the huntite and barite mineral-based polymer composite brake friction materials produced for automobiles exhibited performance following the brake pad characteristics.

Whey protein fibrils enhance fat-related texture of emulsion systems: Translating structural changes to textural perception

Thickeners display great potential for fat substitution in emulsion systems. The underlying mechanisms remain understudied because of the difficulty of defining the structure of thickeners (e.g., compositional and structural complexity). Herein, we designed a thickened emulsion with precise structure and high kinetic stability by blending whey protein fibril dispersions and fragmented freeze-dried whey protein fibril (FWPF)-stabilized emulsions. The structural changes of the blends regarding to microstructure, rheology, and tribology that were determined by confocal laser scanning microscopy, transmission electron microscopy, the shear flow test, the oscillatory shear test, the coefficient of friction test, etc. were achieved by: 1) increasing fibril concentration; 2) reducing electrostatic repulsion among fibrils, aiming to decipher how the structural changes induced by thickening effect were translated into textural perception. We demonstrated that the perceived thickness of the blends had a positive linear correlation with their bulk rheology regardless of the way inducing structural changes, which was mainly determined by the magnitude of interactions between structural units and their collective macroscale response. The perceived grittiness was detrimental to the perceived smoothness and creaminess due to the formation of large irregular protein aggregates with increasing fibril concentration even though irregular protein aggregates enhanced lubricity of the blends in the tribological test. However, the similar irregular protein aggregates induced by the reduction of electrostatic repulsion among fibrils did not change the perceived grittiness/smoothness, demonstrating the combined role of thickener concentration and microstructure in the perception of grittiness and smoothness. Moreover, we found that the perceived creaminess was enhanced by the reduction of electrostatic repulsion, indicating that it reflected the combined textural aspects of the oil-in-water emulsion. Our findings would provide a structural design strategy for developing reduced-fat foods with desired sensory properties.

Airport pavement performance evaluation of pavement fog seal based on optimized test technology

Fog seal technology is widely used in airport asphalt pavement. The research on the performance and application of fog seal material is basically at the level of modified emulsified asphalt. The fog seal test method in the existing specification has defects. Three kinds of fog seal materials with different substrates were selected in this paper. Based on the characteristics of fog seal treatment and the relevant specifications of fog seal and airport pavement. Wet Track Abrasion Test (WTAT), Cantabro test, Water seepage test, and Pendulum instrument tester pavement friction coefficient test were improved. Test the pavement performance of different types of fog seals. The results show that the mass loss of material C was less than 10% after 200 and 400 cycles of wear. The improvement effect of material C on raveling resistance and impermeability was far better than that of materials A and B. The improvement of material C on the raveling resistance of the mixture could reach 50%. The immediate improvement effect on the impermeability was nearly 100%. The skid resistance performance of the three fog seal materials decreased after treatment. The decrease in material C was more significant than in materials A and B. In constructing material C, the dose of emery should be appropriately increased. It was advisable to not be less than 0.35 kg/m2. The fog seal layer improves pavement performance. It has reference significance for using fog seal technology to treat early airport pavement diseases.

The investigation of wear properties of nanoparticle-reinforced epoxy composite material surfaces

This study added nano-sized Al2O3, Boron, and TiO2 powders to the epoxy polymer at 0.5% and 1% ratios. Abrasive wear resistance properties of nanoparticle-reinforced epoxy polymers were investigated. First cylindrical specimens with and without additives were prepared for realizing the experimental research. Pin-on discs were used for the wear test of epoxy samples. The mass losses were measured via a precision scale. According to the results, the boron nanoparticles have increased the epoxy specimens’ resistance. As a result of the experimental studies, it was observed that the wear resistance of the epoxy composite increased with each nano-sized powder added to the epoxy. SEM and optical profilometry investigated the composites’ friction coefficient and surface morphology. As a result of friction coefficient and wear weight loss tests, the highest wear resistance was obtained in 1% boron powder nano-reinforced epoxy composites. It was observed that the epoxy friction coefficient was in the range of 0.4–0.6, which decreased to the range of 0.2–0.4 with the addition of nano boron. The surface roughness value after epoxy wear was measured as 1.4 μm. With the addition of nano boron, this value was measured as 0.32 μm. Optical profilometry and SEM imaging results also support these values.

Effect of the carboxyl group number of the complexing agent on polishing performance of alumina slurry in sapphire CMP

Alumina abrasive has a high polishing rate in the polishing process, but there are issues that need to be addressed with poor dispersion and poor post-polishing surface quality. This study used complexing agents with various numbers of carboxyl groups to prepare a series of alumina slurries. Scanning electron microscope images and zeta potential analysis demonstrated that the complexing agents could effectively increase the absolute value of alumina particles’ zeta potential and significantly enhance their dispersibility. Additionally, utilizing the UNIPOL-1502 polishing machine, the chemical mechanical polishing (CMP) performance of polishing slurries with complexing agents on sapphire substrates was investigated. According to the findings, as the carboxyl group count rises, material removal initially increases and subsequently declines. The material removal rate using alumina slurry added with complexing agent disodium ethylenediaminetetraacetic acid (the number of carboxyl groups is 4) can reach up to about 4.0 μm/h, which is 52% higher than that without complexing agents, while the average surface roughness of 0.96 nm can be obtained, which is 51% less than that without complexing agents. The X-ray photoelectron spectroscopy results showed that the complexing agents can react with the abrasive particles and sapphire substrates. The friction coefficient test and contact angle test revealed that slurries with complexing agents demonstrated excellent wettability and mechanical action. The sapphire surface becomes smoother as a result of the synergistic effect of chemical etching and mechanical removal.

Laboratory evaluation of microwave heating and skid resistance of pavement friction surfacing using calcined bauxite and magnetite aggregates

A high friction surface treatment (HFST) with magnetite (MT) aggregates instead of conventional calcined bauxite (CB) aggregates as microwave absorbers were prepared in this paper. The deicing properties by microwave heating and long-term skid resistance of HFST with different proportions of CB and MT aggregate were evaluated. The deicing properties by microwave heating of HFST were determined by electromagnetic characteristics, heating surface temperature, and microwave deicing time (MDT) tests. The long-term skid resistance of the HFST was characterized by conducting dynamic friction coefficient and mean profile depth (MPD) tests after long-term polishing using a three-wheel polishing device. The results showed that the electromagnetic characteristics of HFST were enhanced greatly by the addition of MT. The microwave heating efficiency of HFST was enhanced by the increase of MT substitution rate, which further enhanced its microwave deicing efficiency. The microwave deicing efficiency of HFST with MT substitution rate of 25% was 1.4 times that of HFST with MT substitution rate of 0%. Long-term skid resistance of HFST was reduced by the addition of MT, however, HFST with MT substitution rate of 25% also maintained a terminal μ40 and μ60 above 0.7, which can provide higher friction comparable with other high friction aggregate such as taconite, basalt, emery and flint. To improve the deicing properties by microwave heating and maintain high skid resistance, 25% MT replacement rate in HFST is recommended.

High efficiency chemical mechanical polishing for silicon wafers using a developed slurry

Improving the material removal rate (MRR) of silicon wafers is a challenge in chemical mechanical polishing (CMP), to meet the demands of the development of integrated circuits. In this study, four environmentally friendly additives, including sorbitol, gluconic acid, citric acid, and ammonium citrate, were incorporated into polishing slurries to promote the MRR of silicon wafers. The polishing results reveal that the highest MRR was obtained by ammonium citrate as an additive. When the concentration of ammonium citrate was 0.05 mol/L, the MRR increased by 71.6% to 1979.88 Å/min, and the surface roughness Sa was decreased from 1.131 nm to 0.563 nm. Meanwhile, the polishing slurry containing colloidal silica as abrasives maintained good dispersibility. Polishing mechanism was interpreted using electrochemical analysis, X-ray photoelectron spectroscopy, and coefficient of friction tests. It is indicated that NH4+ions, generated by hydrolysis of ammonium citrate, could modify the electrical characteristics of the silicate layer and catalyze the chemical reactions between Si atoms and H2O on the surface of silicon wafers. This work emphasizes the interfacial action between the polishing slurry and silicon wafers and provides a new idea for high efficiency CMP of silicon wafers in the manufacture of integrated circuits and photovoltaic industry.

Mechanical properties of innovative prefabricated friction pendulum bearing with concrete-filled steel tube system

An innovative prefabricated seismic isolation system known as a friction pendulum bearing with a concrete-filled steel tube (FPB-CFST) was proposed to improve the mechanical performance and accelerate the construction process of the isolation layer. Unlike the traditional friction pendulum bearing-pier system, which consists of a cast FPB isolator and two cast-in-place reinforced concrete buttresses, the CFST was selected as the main supporting structure, and a spherical curvature surface (SCS) manufactured by a pressing process was attached to the CFST to slide the superstructure in the proposed FPB-CFST system. A construction procedure for the FPB-CFST was proposed, and a series of FPB-CFST specimens with various SCS radii were fabricated. The axial local compressive and compressive shear behaviors of the FPB-CFST were experimentally investigated. Friction coefficient tests were conducted to gain insight into the friction of the FPB-CFST. The mechanism of the proposed FPB-CFST subjected to axial local compression and compressive shear was discussed. The effects of sliding velocity and equivalent pressure of the bearing material on the friction coefficient were evaluated. The influences of the radius of the SCS and local compression ratio on the behavior of the FPB-CFST were addressed. The force model and design method of an FPB-CFST subjected to axial local compression and compressive shear are presented.

Experimental Study on the Effects of New Foam on the Improvement of Sandy Soil for Earth Pressure Balance Shield

In this paper, starting from the foaming amount, half-life and other indicators, the surfactant with excellent performance is optimized, and the optimal compound ratio and appropriate foam stabilizer, viscosity enhancer, and additives are studied. A new type of foam agent formula for the EPB shield is developed. The performance of the new foam agent is compared with that of domestic foam and imported foam from the aspects of foaming rate, stability, micromorphology and temperature resistance, which verifies that it meets the parameter requirements and advantages of a foam agent for shield tunneling. Then, by means of laboratory tests, such as the mixing test, friction coefficient test, adhesion resistance test, slump test and direct shear test, the improvement effect of the new foam agent is compared with existing foam agent products at home and abroad, and the improvement effect of the new foam agent on soil is evaluated. The formulation of the new foam agent is as follows: 1.6% sodium dodecyl sulfate (SDS) + 8% dodecyl dimethyl betaine (BS-12) + 7% dodecanol + 0.06% guar gum + 0.6% ammonium chloride. The foaming rate, stability, microstructure and temperature resistance of new foam meet the requirements of shield construction. New foam, imported foam and domestic foam have advantages in sand and soil improvement experiments, but from an economic point of view, the new type of bubble is better than the other two. A new type of shield foam agent is prepared to meet the needs of construction. There is a big advantage in terms of price.

Experimental study on the high-speed frictional behavior between the tire and asphalt pavement

Driving speed, pavement type, surface characteristics, intermediate media, and tire properties are the key factors influencing the frictional behavior between tire and pavement. Although there are many kinds of equipment for friction coefficient tests based on the rubber-pavement contact mechanism, there is still a lack of equipment that can simulate the skid resistance behavior of high-speed vehicles based on real tire in the laboratory. Therefore, High-speed Friction Testing (HSFT) equipment was developed based on real tire loading, which well solves the deficiency of the current test methods. Based on this test platform, multi-factor coupling skid resistance tests were carried out on the asphalt concrete (AC-10/13/16) and the Open-Graded Friction Coarse (OGFC-10/13/16) samples. Statistical comparison and nonlinear fitting analysis were conducted on the results under various loading conditions The results show that driving speed, water film thickness, and tire load are all negatively correlated with skid resistance, and their influence extent can be ranked as water film thickness > tire load > driving speed. The established μHSFT skid resistance model based on multi-factor coupling shows high reliability, which can be used as the basis for pavement construction and is an important reference for future unmanned driving technology.

ANALYSIS OF OIL ABSORPTION AND FRICTION COEFFICIENT OF BAMBOO POWDER, COCONUT POWDER, GLASS POWDER, AND COPPER POWDER COMPOSITES FOR CLUTCH PADS

This study aims to determine the characteristics of the absorption test with SAE 10W-30 and the friction coefficient test with the ASTM D 3702-94 test standard on composite clutch pads made from bamboo powder, coconut powder, glass powder, and copper powder. It is based on the considerations that there are abundance of natural resources of bamboo and coconut with that is still not optimally utilized as well as the discovery of several hazardous clutch lining (asbestos) basic material properties. In each test, each composition variation was tested 3 times and from the data, the average value of the composition variation was taken. Based on this research, the specimen with the highest oil absorption value is specimen combination 3 (BB20KL20CU0KC20) with an absorption value of 17.98% and the specimen with the lowest absorption value is specimen combination 2 (BB20KL20CU5KC15) with an absorption value of 4.88%, and the specimen with the highest percentage change in volume is specimen combination 1 (BB20KL20CU10KC10) with a percentage of 3.30%, and the specimen with the lowest percentage change in volume is specimen combination 2 (BB20KL20CU5KC15) with a percentage of 1.01%. From the results of the combined friction coefficient test, specimen 3 (BB20KL20CU0KC20) has the highest friction coefficient value of 0.54526 and specimen 2 (BB20KL20CU5KC15) has the lowest friction coefficient value of 0.16923.