Friction RandomPOD—A new method for friction measurement in noncyclic, multidirectional, dynamic pin-on-disk tests for orthopaedic bearing materials

The 16-station, computer-controlled RandomPOD wear test device was re-designed into a friction measurement device, Friction RandomPOD. motion implemented by servo-electric x-y-stage and the load proportional-pneumatic. direction of sliding, velocity ( v ), acceleration, magnitude L ) varied randomly continuously. nominal contact pressure p between 0 2.4 MPa 40 mm/s. In first version frictional force components were continuously measured two miniature cells in perpendicular directions. second version, done with three-axial, commercial cell. resultant divided instantaneous order to obtain coefficient μ at frequency 200 Hz. Due light accurate design vibrations absent signals although measurements most dynamic. Hence no filtering needed. Serum lubricated polyethylene/CoCr tests revealed non-symmetric distributions , power P vs. pv .