Low-speed oblique elastic impacts frequently occur in heat exchangers and other equipment having loosely supported tubes or pipes. In order to experimentally study friction during such impacts, a pendulum-type impact apparatus was developed. A hardened steel sphere at the end of the pendulum collides with a flat steel surface for a range of approach velocities and angles. The present investigation examined eight velocities from 8 to 93 mm/s and impact angles (measured from the common normal) of 0 to 75 deg for each velocity. The normal and tangential contact force waveforms were measured using a triaxial piezoelectric force transducer which was dynamically calibrated. As expected, the results show that the tangential force is less than the limiting Amontons-Coulomb friction predictions at low impact angles. Two regimes of stick-slip and gross-slip friction are clearly distinguished by a new friction parameter called the specific traction ratio. Tangential force reversal was observed at low impact angles, indicating local tangential oscillations. The stick-slip results are consistent with a partial-slip model where the contact zone has a central sticking region surrounded by a ring area undergoing slip.
An Experimental Study of Friction During Planar Elastic Impact
Contributed by the Pressure Vessels and Piping Division and presented at the Pressure Vessels and Piping Conference, Atlanta, Georgia, July 22–26, 2001, of THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS. Manuscript received by the PVP Division, March 20, 2001; revised manuscript received July 20, 2001. Associate Editor: M. J. Pettigrew.
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Osakue , E. E., and Rogers, R. J. (July 20, 2001). "An Experimental Study of Friction During Planar Elastic Impact ." ASME. J. Pressure Vessel Technol. November 2001; 123(4): 493–500. https://doi.org/10.1115/1.1408304
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