Study of thermal effects associated with crack propagation during very high cycle fatigue tests

Nicolas Ranc (1) , Danièle Wagner (2) , Paul C. Paris (3)

1 LMSP - Laboratoire de Mécanique des Systèmes et des Procédés
2 LEEE - Laboratoire d'énergétique et d'économie d'énergie
3 LAMEFIP - Laboratoire Matériaux Endommagement Fiabilité et Ingénierie des Procédés

This paper studies the thermal effects associated with the propagation of a fatigue crack in a gigacycle fatigue regime. Ultrasonic fatigue tests were carried out on a high-strength steel. The temperature fields measured by infrared thermography show a significant and very local increase in the temperature just before fracture. In order to better understand these thermal effects and to make a connection with the initiation and the propagation of the fatigue crack, a thermomechanical model is developed. The fatigue crack is modeled by a circular ring heat source whose radius increases with time. The numerical resolution of the thermal problem allows determination of the time evolution of the temperature fields in specimens and shows a good correlation with experiment. These results provide experimental proof that in a very high cycle regime, the propagation stage of the crack constitutes a small part of the lifetime of the specimen.

Mots clés: Thermal effects; Temperature; Infrared pyrometry; Very high cycle fatigue

Domaines: Matériaux

Nicolas Ranc, Danièle Wagner, Paul C. Paris. Study of thermal effects associated with crack propagation during very high cycle fatigue tests. Acta Materialia, 2008, 56 (15), pp.4012-4021. ⟨10.1016/j.actamat.2008.04.023⟩. ⟨hal-00283642⟩