The Effect of Graphene Coating on Surface Roughness and Friction Properties of Polyester Fabrics

In this article, the surface roughness and friction coefficient values of graphene coated fabrics were examined. Fabrics were coated with three different graphene concentrations (5 %, 10 % and 20 %) with the knife-over-roll principle. The surface roughness of samples was measured by Accretech Surfcom 130A. Various surface roughness parameters of the coated fabrics were evaluated. Static and kinetic friction coefficients of coated fabrics were measured by Labthink Param MXD-02 friction tester using the standard wool abrasive cloth. It was observed that the coating concentration affected the frictional and roughness properties of fabrics. Experimental results showed that fabric surface roughness and friction coefficient values decreased significantly, especially at 20 % concentration. It was concluded that the coated fabrics produced could be used in applications such as anti-wear clothing.

Linear friction tester design and validation

Due to the complexity of friction phenomena, empirical analysis is the best way to predict the friction coefficient. To accomplish this, laboratory test rigs are needed. Although a rotary dynamic friction test bed was available to the authors, it had its limitations, such as low speed, inducement of lateral force, and the limitation of testing samples with different shapes. This paper will explain the process of designing and manufacturing a novel test setup for measuring friction and wear of the tire. The newly designed test rig can apply dynamic loading during the tests, and it can automatically measure the wear rate and temperature between cycles. In addition, it can be used for measuring the wear rate of rubber samples sliding on different types of surfaces. Therefore, experiments can be run under more controlled conditions. The designed linear friction tester can slide flat and round rubber samples approximately three meters across a large flat surface. The frictional force of rubber samples can be measured for various normal loads, velocities, and surface conditions. The new setup can automatically control the applied normal load on the sample using proportional–integral–derivative controller control. The important difference between this novel design and the existing testers used by other researchers is implementing the ball screw technology and the servo motor with high accuracy encoder to achieve highly accurate test results. In this design, the new mechanism for the ball screw is designed to increase the speed limit and eliminating vibrations while keeping the precision. In addition, in this design, the sample's mass can be measured automatically after each test cycle, thus providing a measure of the rate of wear of the rubber. In this study, the data collected by the linear friction tester is validated by comparing the data to the data collected by the dynamic friction tester (a validated rotary friction tester that exists in CenTiRe Lab). The data collected by the new setup was later used to benchmark the Persson analytical friction model.

Friction Characteristics of Surface Nitriding Modification Layer of Ti-6Al-4V ELI Titanium Alloy in Seawater Environment

In order to study the tribological properties of titanium alloy materials and reinforced PTFE pairs treated by surface nitriding modification in seawater environment under low speed and high load, the physical properties of surface nitriding modified treatment were observed and measured with Ti-6Al-4V ELI as the substrate, and the samples of substrate and surface nitriding were modified as disks to 25% fiberglass , 15% glass fiber +5% graphite and 60% tin bronze reinforced PTFE as distribution pins, the friction properties of substrate and surface nitriding modification layer in seawater environment were studied by friction tester. The results show that the friction coefficient between titanium alloy and auxiliary pair is above 0.1, the friction coefficient of titanium alloy surface treatment specimen is lower than that of TC4 titanium alloy, the wear of surface nitriding modified treatment sample is significantly slight, the friction coefficient of 60% tin bronze distribution is the highest, and the friction coefficient of 15% fiberglass +5% graphite is about 15% higher.

Analysis of the Actual Contact Surface of Selected Aircraft Tires with the Airport Pavement as a Function of Pressure and Vertical Load

The contact surface of the wheel with the airport surface is important for the safety of flight operations in the ground manoeuvring area. The area of the contact surface, its shape and stress distribution at the pavement surface are the subject of many scientists’ considerations. However, there are only a few research studies which include pressure and vertical load directly and its influence on tire-pavement contact area. There are no research studies which take into account aircraft tires. This work is a piece of an extensive research project which aims to develop a device and a method for continuous measurement of the natural airport pavement’s load capacity. One of the work elements was to estimate the relationship between wheel pressure and wheel pressure on the surface, and the area of the contact surface. The results of the research are presented in this article. Global experience in this field is cited at the beginning of the article. Then, the theoretical basis for calculating the wheel with the road surface contact area was presented. Next, the author’s research views and measurement method are presented. Finally, the obtained test results and comments are shown. The tests were carried out for four types of tires. Two of them were airplane tires from the PZL M28 Skytruck/Bryza and Sukhoi Su-22 aircraft. Two more came from the airport ASFT (airport surface friction tester) friction tester-one smooth ASTM; the other smooth retreaded type T520. The tires were tested in a pressure range from 200 to 800 kPa. The range of vertical wheel load on the pavement was 3.23–25.93 kN for airplane tires, and 0.8–4.0 kN for friction tester tires. The tests proved a significant influence of the wheel pressure value and wheel pressure on the surface on the obtained contact surface area of the wheel with the surface. In addition, it was noted that the final shape and size of the contact surface is affected by factors other than wheel pressure, tire pressure and dimensions.