Dry Sliding Friction Experiments at Elevated Velocities

Abstract

An enhancement of an existing tribometer device developed by Philippon et al. (2004, Wear 257, 777-784) is presented in this work. This experimental device is made up of a dynamometer ring and a specific load sensor allowing to apply an apparent normal force on specimens and to measure frictional forces respectively. Problems such as static calibration of both distinct parts supported by conducted numerical simulations is given and described in detail. Further discussion, again supported by numerical analysis, validates the placing of the strain gauges and explains the problems of sensitivity of loading surface and cross-sensitivity. The entire experimental setup is then discussed explaining the mounting of the strain gauges located on the tribometer device, showing the configuration of the Wheatstone quarter-bridges, presenting the signal conditioning amplifier system and the digital oscilloscopes which all together create one uniform data acquisition system. The set up is adapted on a gas gun to carry the Steel 1080 on Steel VascoMax 300 experiments. The main set of experiments with sliding velocities varying from 10 to 60 m s )1 are performed in the same tested setup. The recordings of normal and tangential forces leading to the friction coefficient determination are discussed. The values of dry friction coefficient l according to the experimental parameters are in good agreement with those observed in the literature. Using this new configuration, the effects of the sliding velocity on the surface roughness changes and on the dry fiction coefficient are also investigated. Moreover, very interesting relations between wear and sliding velocity are observed.

Literature Review on the Theory and Measurement of Dry Sliding Friction of Metals

“…The Kolsky bar is commonly utilized in a torsional configuration to measure friction coefficients [38]- [43], where sliding velocities up to 10 m/s are achievable [38], [39], [43]. Philippon [28] and others [6], [7], [10], [18], [27] coupled a gas gun and dynamometer ring to impart various sliding velocities and normal forces to tribological pairs, as shown in Figure 21. Here, a gas gun is used to transfer a compressive force directly to the mobile specimen, where the setup is similar to a compression Kolksy bar, but without the incident bar.…”

“…common experimental systems and their corresponding achievable sliding velocity and normal pressure regimes[27]. Perhaps the most widely used device for measuring the kinetic friction coefficient is the pin-on-disk configuration, where the friction force between a pin and rotating disk is measured.…”

A Mechanism Design of Friction and Wear Test Based on Liquid Medium

“…2 shows the system working principle of tribometer. The main procedures includes: (i) the pressure sensor captures digital signals during testing; (ii) digital signals are processed via amplifier and converted by A/D converter ; (iii) friction coefficient curve is then obtained using the digital signals processed by CPU; (iv) the curve result will be displayed on the monitor or printed by the printer [8]. In addition, the computer can control the motor to obtain the friction parameters under different states.…”

Experimental Measurement of Dynamic Forces Generated during Short-Duration Contacts: Application to Blade-Casing Interactions in Aircraft Engines

“…Hydraulic high speed tensile testing machines are also used to generate shortduration contacts [17,18] but their performances in terms of interaction velocity are limited (< 5 m/s). We chose to use a ballistic bench which allow to generate a short and unique interaction and to obtain a large range of interaction speed (from 3 m/s to 600 m/s) [19][20][21][22][23][24].…”