Environmental effects in fretting

Tribocorrosive Aspects of Tungsten Carbide, Silicon Nitride, and Martensitic Steel under Fretting-like Conditions

“…Pre-tests delivered an effective loss of 4 µm per half-stroke due to elastic properties of the setup. Thus, the initial conditions with 92 µm stroke length coincide with the boundary between reciprocating sliding and gross slip fretting mode [57]. Gross slip was achieved shortly after the start of the respective experiment due to wear-related surface alignment.…”

“…A second source of material damage is related to the depletion of lubricant in a fretting contact. This leads to an increase in tensile stress at the surface, whereas the increase in W F is generally observed later than in a non-lubricated fretting contact [57]. If tribocorrosion is a consequence of fretting, two main mechanisms of material damage are regularly observed:…”

Structural integrity of shot peened Ti6Al4V specimens under fretting fatigue

“…It is more convenient to specify the cause of such a motion, and, therefore, to use the expression fretting wear as fretting for which the small displacements are a consequence of external vibrations, affecting at least one of the two contacting parts, and fretting fatigue as fretting for which the small displacements are a consequence of cyclic deformations, at least in one of the two contacting parts (Kapsa 2011).…”

“…More precisely, by representing the contact force against the tangential displacement range, 2δ, between two points in the undeformed region of each body (Fig. 1), and by defining the parameter e as the ratio between the displacement amplitude δ and the radius a of the Hertzian contact area, three domains can be distinguished (Kapsa 2011;Fouvry et al 1995;Zhou et al 2000) (Fig. 1): partial slip and gross slip are located in a domain characterised by e < 1, when a part of the wear scar is never in contact with the environment, whereas reciprocating sliding is located in a domain characterised by e > 1, when the entire wear scar is in contact with the environment.…”

“…From a wear phenomenological point of view, damage is associated with contact stress and sliding conditions (Kapsa 2011): (i) When the contact is composed of a stick area and a slip area (Fig. 1), damage is mainly due to cracking phenomena (crack initiation and propagation) as a consequence of vibrations/cyclic deformation effects in the material, inducing time-varying contact stress; (ii) When the contact is whole sliding (Fig.…”