The influence of surface roughness magnitude and direction on dry static friction coefficient between two similar steel samples has been studied through an experiment. A testing apparatus has been designed and fabricated to measure the friction coefficient for a few forms of surface asperity. According to the results of the experiments, dry friction coefficient is affected by both magnitude and...

objective: to investigate the friction of rabbit’s knee joint with designed pendulum friction tester to diagnose and evaluate different pathological and therapeutic conditions following haemarthrosis, osteoarthritis, and other joint disorders. materials and methods: friction coefficient of 10 adult male albino rabbit’s joint (5 right and 5 left knees) weighted 1.59 ± 0.27 kg, after designing a...

Friction is a very complicated phenomenon arising at the contact of surfaces. Experiments indicate a functional dependence upon a large variety of parameters, including sliding speed, acceleration, critical sliding distance, temperature, normal load, humidity, surface preparation, and, of course, material combination. In many engineering applications, the success of models in predicting experim...

many studies have been conducted focusing on the effects of friction coefficient or texture depth on the highway accident risk. however, combined effects of these parameters have not been still addressed. in this research the interaction between friction coefficient, texture depth and accident rate in 30 freeway sections were examined. the accident data were gathered and an apparatus was design...

After falls, skiers or snowboarders often slide on the slope and may collide with obstacles. Thus, the skier’s friction on snow is an important factor to reduce incidence and severity of impact injuries. The purpose of this study was to measure snow friction of different fabrics of ski garments with respect to roughness, speed, and contact pressure. Three types of fabrics were investigated: a c...

This paper reviews rock friction and the frictional properties of earthquake faults. The basis for rateand state-dependent friction laws is reviewed. The friction state variable is discussed, including its interpretation as a measure of average asperity contact time and porosity within granular fault gouge. Data are summarized showing that friction evolves even during truly stationary contact, ...

Engineers encounter the problem of friction in any mechanical system. Friction force is strongly nonlinear and varies considerably while the system is working. In the case of high-precision applications friction makes the situation even more complex, as the stick-slip effect occurs near the target position. This paper introduces a pneumatic servo-system for investigation of the behavior of fric...

In this paper friction induced limit cycles are predicted for a simple motion system of a single motor-driven inertia subjected to friction and a PID-controlled regulator task. The two friction models used, i.e., (i) the dynamic LuGre friction model and (ii) the static Switch friction model, are compared with respect to the so-called hunting phenomenon. Analysis tools originating from the field...

We studied the ability of surfactants to reduce friction by boundary lubrication for a bulk hydrogel sliding on a solid surface in an aqueous solution. A piece of negatively charged polyelectrolyte hydrogel was slid across solid surfaces with various levels of hydrophobicity, using a strain-controlled parallel-plate rheometer in water. A dramatic reduction in the sliding friction, especially in...