Characterization of mixed and gross slip fretting wear regimes in Ti6Al4V interfaces at room temperature

On the Necessary but Sufficient Amount of Grease to Obtain Fully Lubricated Fretting Regime in Moist Air for SUJ2 Bearing Steel against S15C Carbon Steel

“…Gross slip gives rise to relief of stress, accompanied by progressive surface damage, such as material removal. However, in this regime the relative displacements are still so small that the debris never leaves the interface causing a third body effect where the debris grinds into the mating surfaces [5].…”

“…Thus, only relatively small amounts of debris are escaping at the sides of the wear track [5][6][7].…”

“…Then the slip ratio ( Fig. 2) can be defined as the ratio of the slip and displacement amplitudes [1][2][3][4][5]. However, from an experimental standpoint, by neglecting the end effects at the extremities of the hysteresis loop, the slip ratio can be also calculated as the ratio between the dynamic and static friction forces ( Fig.…”

“…Here V t is the volume of the fretting scar, which can be approximated with a semi-ellipsoid to easily estimate its volume [5][6][7]; s A is the slip amplitude and t N is the total number of fretting cycles. Figure 8 presents variation of the mean wear rate w of the disk specimen versus the relative humidity RH of the moist air for various amounts of grease.…”

“…Depending on the loading conditions, material properties and environment, fretting can cause fretting wear, which combines all four basic mechanisms (oxidative, adhesive, surface fatigue and abrasive), or fretting fatigue, which combines surface and bulk fatigue [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Fretting wear and fatigue severely decrease the life of machine elements (e.g., rolling element bearings, screw and rivet assemblies, etc.)…”