Dissipation Assessments During Dynamic Very High Cycle Fatigue Tests

Antoine Blanche (1) , André Chrysochoos (1, 2) , Nicolas Ranc (3) , Véronique Favier (3)

1 LMGC - Laboratoire de Mécanique et Génie Civil
2 ThM2 - ThermoMécanique des Matériaux
3 PIMM - Laboratoire Procédés et Ingénierie en Mécanique et Matériaux

This paper presents an experimental device developed to detect and estimate dissipated energy during very high cycle fatigue tests (VHCF) at high loading frequency (20 kHz) and low stress (i.e. far below the yield stress). Intrinsic dissipation is computed using local expressions of the heat diffusion equation and thermal data fields provided by an infrared focal plane array camera. The results obtained from tests performed on pure copper specimens show that dissipated energy exists whatever the attainable stress range and show that the dissipated energy rate is not constant throughout the test. Both findings are respectively incompatible with the concepts of fatigue limit based on elastic shakedown or on stabilized cyclic state associated with the mechanical hysteresis loop (viscoplastic shakedown).

Mots clés: Hysteresis loop; Intrinsic dissipation; Ultrasonic fatigue; Infrared thermography; Fatigue limit

Domaines: Matériaux; Mécanique [physics.med-ph]; Mécanique des structures [physics.class-ph]

Antoine Blanche, André Chrysochoos, Nicolas Ranc, Véronique Favier. Dissipation Assessments During Dynamic Very High Cycle Fatigue Tests. Experimental Mechanics, 2015, 55, pp.699-709. ⟨10.1007/s11340-014-9857-3⟩. ⟨hal-01178226⟩