The development and early propagation of fatigue cracks can be considered in terms of the basic damage mechanisms and the relative size of the crack with respect to applicable microstructural feature(s). In this work, a brief overview is first presented of mesoscopic/grain scale approaches used to study the fatigue crack formation and early growth in the micro-structurally small crack (MSC) growth regime, where fatigue crack growth rates are strongly dependent on microstructural features such as grain size, second phase particle size and spacing, etc. Particular attention will be given to approaches which rely on a correlation of fatigue indicator parameters (FIPs) with measured locations of fatigue crack formation within polycrystals, using representative crystal plasticity based finite element models of the microstructure. It will also be shown how various FIPs have increasingly been used as mesoscopic indicators to relate to processes of fatigue crack growth of MSCs. In the second part of this presentation, alternative macroscopic fatigue formulations required when considering complex conditions of high temperatures, environmental effects and thermomechanical loadings seen by, e.g., discs and blades in jet engines, will be discussed. Such macroscopic formulations are based upon fundamental physical processes, and generally rely on a scalar measure of damage to account for complex loading conditions. A representative example will be given in the form of a recently proposed time-dependent (or incremental) fatigue damage formulation developed for single-crystal nickel-based superalloys.
Prof. Busso is currently Chief Academic Advisor and a National 1000 Talent Professor at the Harbin Institute of Technology, in Shenzhen, China. He was till May 2018, the Scientific Director of the National Aerospace Research Centre of France (ONERA) in the areas of Materials and Structures. From 2005 to 2013, he was a Professor of the Ecole des Mines de Paris and, from 1994 to 2005, Professor at Imperial College’s Department of Mechanical Engineering in London, UK. Dr. Busso got his PhD (1990) in Mechanical Engineering at the Massachusetts Institute of Technology (MIT), USA. In August 2014, Dr. Busso was elected a Fellow of the British Royal Academy of Engineering. His research involves micromechanics studies of deformation and fracture of materials and interfaces, with an emphasis on the development of multiscale and multiphysics concepts in mechanistic models to predict deformation and fracture processes. He is currently an Editorial Board member of Philosophical Magazine, the Journal of Multiscale Modelling, the Journal of Mechanical Behavior of Materials, and the Journal of Materials Discovery, and was a former associate editor of the ASME Journal of Eng. Materials and Tech. and the Aerospace Lab Journal, and an Editorial Board member and guest editor of the Int. Journal of Plasticity. He has authored and edited 12 scientific books, and has published over 135 peer-reviewed articles (Hindex of 34 with 3688 citations in Google Scholar). He is an advisor to industry worldwide including USA, the British, Dutch and French research councils, amongst others.