Friction measurement at low sliding speed using a servohydraulic tension-torsion machine

A method is presented for the determination of the coefficient of friction at low sliding speeds down to 3 nm/s. It is also possible to vary the contact pressure. The maximum average contact pressure is 40 MPa in the present test configuration, where a servohydraulic tension-torsion machine is used. The method, involving test equipment, measurement and the principles of evaluation, is exemplified by a study where the variation of the coefficient of friction with sliding velocity contact pressure and surface roughness is investigated for the material combination steel and concrete. The measurements have been performed as a 2³ factorial design. An error analysis was performed and the relative measurement uncertainty when determining the coefficient of friction was estinated to be 1.2 percent.