Dissipated Energy Measurements of Metal Material during High-cycle Fatigue Test Process YuanLI∗,a,b, Francois MAQUINc, Zhicheng LIUa, Chao JIANGa, XuHANa aState Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, College of Mechanical and Vehicle Engineering, Hunan University, Changsha, 410082, China bDepartment of Traffic and Transportation Engineering, College of Basic Education for Commanding Officers, National University of Defense and Technology, Changsha, 410003, China cLaboratoire de Mecanique et Procedes de Fabrication(LMPF), Arts et Metiers ParisTech, BP 508 Rue St Dominique, Chalons-en-Champagne, 51006, France Abstract In this paper, the high-cycle fatigue characterization of 316L stainless steel was studied based on dissipated energy measurement. At first, the dissipated energy per cycle was deduced from temperature field of specimen surface using an experimental mechanical method. Then, variations of dissipation energy per cycle were in-situ monitored during each high-cycle fatigue test under different stress levels. The results show that dissipated energy is mainly constant after the initial 5% cycles of total fatigue lifetime. Dissipated energy versus fatigue lifetime fitting curve shows the same pattern as the traditional stress versus fatigue lifetime curve. Keywords: Dissipated energy, metal material, high-cycle fatigue, fatigue lifetime 1. Introduction High-cycle fatigue characterization of metal material is a time consuming and expensive statistical process. Thus, various theories and alternative accelerated methods to estimate fatigue characteristics have been of great interest at home and abroad [1] over a number of years. From an energy point of view, under the repeated mechanical energy input provided by the loading, dislocation are created and rearranged into the specific micro-structures. These microstructural modifications accompanied with heat dissipation energy, lead to progressive energy storage. By observing the local temperature rise, many authors developed many accelerated methods to estimate fatigue limit or S-N curve, such as one curve method [2]and two curve method [3], Amiri method [4], quantitative thermographic method [5], self-heating method [6] et.al. Unfortunately, fatigue characteristics resulting from these approaches are questionable: the local temperature rise is correlated with heat-conduction, heat-convection and heat-exchange, and especially affected by the environment temperature fluctuation, and the physical reasons leading to these estimations are not yet well understood. A better understanding of the physical origin of dissipated energy is required to better interpret the local temperature rise. The relative dissipated energy was firstly deduced from local temperature ∗Corresponding author: yuanli@nudt.edu.cn Preprint submitted to 13th International Conference on Fracture January 16, 2013
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