Fast determination of fatigue behavior of materials beyond one billion cycle (FastMat); ERC project, consolidator Grant (2017-2022)


Nicolas Ranc

 

Many mechanical structures are submitted to repeated loadings and can break under stress lower than the ultimate tensile stress. This phenomenon is called the fatigue of materials and can be found in many industrial sectors, such as the transport industry, aeronautic industry and energy production. Fatigue design is thus crucial in engineering and it requires the precise characterization of material behavior under cyclic loadings to ensure the safety and reliability of structures throughout their life. An increase in the life span of a structure or a reduction in the number of maintenance phases leads to an increases in the number of cycles applied to this structure. It is presently common to find mechanical systems subjected to several billion cycles, in what is called the gigacycle fatigue domain. The characterization of the fatigue behavior of materials requires fatigue tests to be conducted until fracture for different stress amplitudes. One problem with this method is the test duration, which becomes excessive and beyond possible, particularly for a very high number of cycles. The goal of FastMat is to develop a new method that reduces considerably the duration of fatigue characterization. This method involves the use of only short interrupted tests coupled with a self-heating measurement to characterize the fatigue behavior for very low stress amplitudes. The scientific objective is to develop simultaneously experimental and numerical tools for the fast determination of fatigue behavior. The experimental approach will be developed to estimate simultaneously the dissipation and the stored energy, which directly reflect fatigue damage. For the numerical approach, discrete dislocation dynamics simulations will be developed to establish links between the fatigue damage associated with the evolution of dislocation structures, the stored energy and the dissipated energy.


Some results of FastMat project:

  1. Time resolved X-ray diffraction for stress measurements during ultrasonic fatigue tests, N. Ranc, T. Ors, V. Michel, V. Favier, O. Castelnau, D. Thiaudière, C. Mocuta, 12th International Fatigue Congress (Fatigue 2018), May 27-June 1st 2018 (Presentation).
  2. Estimation de l’énergie dissipée et de l’énergie stockée lors d’une sollicitation de fatigue à très grand nombre de cycles, N. Ranc, V. Jacquemain, T. Ors, V. Michel, V. Favier, O. Castelnau, D. Thiaudière, C. Mocuta, Matériaux 2018, 19-23 novembre 2018 (Presentation).
  3. T. Ors,  V. Michel, V. Favier, O. Castelnau,  D. Thiaudière , C. Mocuta, N. Ranc, Diffraction des rayons-X résolue en temps pour la mesure de contraintes lors des essais de fatigue ultrasonique, Matériaux 2018, 19-23  novembre 2018, Strasbourg (France).
  4. T. Ors, N. Ranc, M. Pélerin, V. Michel, V. Favier, O. Castelnau, C. Mocuta, D. Thiaudière , Time-resolved X ray diffraction applied to an ultrasonic fatigue loading, European Congress on Residual Stresses, 11-14 septembre 2018, Leuven (Belgique).
  5. N. Ranc, T. Ors, M. Pelerin, V. Michel, V. Favier, O. Castelnau, D. Thiaudière, C. Mocuta, Time resolved X-ray diffraction for stress measurements during ultrasonic fatigue tests, Comit Utilisateurs SOLEIL, 18-19 janvier 2018, Saint-Aubin (France).
  6. N. Ranc, M. Pelerin, V. Michel, V. Favier, O. Castelnau, D. Thiaudière, C. Mocuta, Time resolved X-ray diffraction for stress measurements during fatigue tests at 20kHz, Colloque Rayons X et Matière, 14-17 nov. 2017, Lille (France).
  7. N. Ranc, M. Pelerin, V. Michel, V. Favier, O. Castelnau, D. Thiaudière, C. Mocuta, Time resolved X-ray diffraction for stress measurements during fatigue tests at 20kHz, EUROMAT 2017, 17-22 sept. 2017, Thessalonique (Grèce).
  8. N. Ranc, M. Pelerin, V. Michel, V. Favier, O. Castelnau, D. Thiaudire, C. Mocuta, Time resolved X-ray diffraction for stress measurements during ultrasonic fatigue tests, VHCF 73-5 juillet 2017, Dresden (Allemagne).
  9. N. Ranc, M. Pelerin, V. Michel, V. Favier, O. Castelnau, D. Thiaudière, C. Mocuta, Time resolved X-ray diffraction for stress measurements during fatigue tests at 20kHz, Comit Utilisateurs SOLEIL, 19-20 janvier 2017, Saint-Aubin (France).
  10. N. Ranc, M. Pelerin, V. Michel, V. Favier, O. Castelnau, D. Thiaudière, C. Mocuta, Diffraction des rayons X résolue en temps au cours d'essais de fatigue à 20kHz, Journées du GFAC, 17 - 18 nov. 2016, Toulouse (France).