Reverse identification of short–long crack threshold fatigue stress intensity factors from plain fretting crack arrest analysis

• Global description of short-to-long fretting crack arrest conditions (4 materials).
• SIF estimation at the fretting crack tip (kinked crack description).
• Reverse FEM estimation of SIF threshold from fretting cracking: ΔKth(fr).
• Good correlation between fatigue and fretting long crack thresholds (ΔK0(fr) = ΔK0).

Plain fretting systematically implies crack arrest condition when the crack tip is far enough from the surface stressing. Considering such evolution, an original reverse FEM modelling of arrested cylinder/plane fretting cracks is introduced to extract the thresholds SIF of materials (ΔKth). Adjusting contact pressure and cylinder radius, short to long crack arrest responses are quantified and the corresponding “fretting” ΔKth identified. Steel and aluminium alloy analyses (35NiCrMo16, AISI-1034, 7075-T6, 2024-T351) confirm the stability of this approach: the dispersion between long crack ΔKth fretting estimations and conventional fatigue data is less than 10% whereas the short crack evolutions confirm the El-Haddad formalism.