A multiaxial stress-based critical distance methodology to estimate fretting fatigue life

Abstract

ABSTRACT. This work presents a methodology for fretting fatigue life estimation based on the evaluation of a multiaxial fatigue parameter at a critical distance below the contact surface. The fatigue parameter is defined using the Modified Wöhler Curve Method together with a measure of shear stress amplitude based on the Maximum Rectangular Hull concept. To apply the approach in the medium-cycle fatigue regime, the critical distance is assumed to depend on the fatigue life. Available fretting fatigue experiments conducted on a cylinder-on-flat contact configuration made of Al-4%Cu alloy were used to evaluate the methodology. Most of the fatigue life estimates were within factor-of-two boundaries.

Fracture Behavior of Nanoscale Notched Silicon Beams Investigated by the Theory of Critical Distances

“…In other words, failure may occur when on the net section the stress is close to σ UTS , as happens when plane specimens are considered. It is worth noting that, similar to the procedure summarized here, TCD has also been applied successfully under fatigue, [37,38] mixed-mode loading, [39] elevated temperature, [40] and elastic-plastic conditions. [41] The evaluation of the fracture toughness by the TCD in the form of the point method is based on stress analysis ahead of the notch root, as described earlier.…”

Early cracking orientation under high stress gradients: The fretting case

“…Hence, the empirical relation derived for steels and cast irons in Ref. [36] was employed to determine the material characteristic length: (11) where is given in mm, is the uniaxial fatigue limit range (MPa), and is the ultimate tensile strength (MPa). Eq.…”

“…In this approach, the size of the volume element is considered to be directly related to a critical distance expressed in terms of the threshold stress intensity range and the endurance limit of the material. In a recent study [11], a formulation of the MWCM−TCD method, where the critical distance depends on the fatigue life, was applied to a cylinder-on-flat contact configuration. The estimated and observed fatigue lives were found to be in good agreement.…”

Subsurface crack formation and propagation of fretting fatigue in Ni‐based single‐crystal superalloys

“…Fretting refers to the microscale relative displacement in a pair of contact surfaces subjected to an oscillatory loading condition. [1][2][3] Severe stress concentration exists at the edge of contact zone under fretting condition, where the fatigue crack usually initiates. 4,5 The whole process involving crack formation, propagation, and final fracture is defined as the fretting fatigue.…”