Samuel Forest
Centre des Matériaux
Mines Paris PSL University
Presenting in Track 4: Advanced Materials: Design, Processing, Characterization & Applications
Presentation Title: Dynamic Strain Aging Phenomena in Engineering Metallic Alloys: Experiments, Modelling and Impact on Fracture Properties
Abstract: Dynamic strain aging (DSA) phenomena are ubiquitous in engineering metals and alloys and can occur in industrial components under in-service conditions, such as turbine disks in jet and helicopter engines. They result from the interaction of dislocations with diffusing solute atoms or precipitates. They are characterized by serrations on stress-strain curves, formation and propagation of plastic strain rate bands along the specimen, and negative strain rate sensitivity over a range of strain rates and temperatures. Experimental evidence will be provided for several classes of metals, including steels and nickel-base superalloys. Portevin-Le Chatelier (PLC) bands are observed at notches and crack tips and modeled using the Kubin-McCormick approach. Implicit finite element simulations show the effect of strain aging on the bursting of turbine disks with increasing spinning rate. The PLC bands are still observed in metal matrix composites where the particles act as scattering obstacles. 3D tomographic experiments including digital volume correlation show a clear link between PLC bands generated at a crack tip and its ductile propagation. The DSA model is finally combined with the Rousselier model for the simulation of ductile crack propagation in CT specimens of steels and aluminum.
Biography: Samuel Forest is research director at CNRS and professor of continuum mechanics at Mines Paris PSL University. He obtained his PhD in Materials Science and Engineering in 1996. His work aims at introducing the physical aspects of deformation and fracture of materials into the framework of continuum mechanics, especially for aeronautical industrial applications. He has participated in the recent developments of the mechanics of generalized continua including strain gradient plasticity for the simulation of strain localization phenomena.
He has published more than 200 articles in international journals in mechanics and physics of materials and structures. He has supervised more than 50 PhD theses, notably within the framework of projects with industrial partners in aeronautics, energy and material processing. From 2009 to 2018, he directed the CNRS Fédération Francilienne de Mécanique, Matériaux, Structures et Procédés., fostering cooperation among the 14 mechanics laboratories in the Paris region. He received the bronze (1998) and silver (2012) medals from the CNRS, the Jean Mandel Prize (2001) and the Huy Duong Bui Prize (2022) of the French Academy of Sciences. He is a Fellow of the Euromech Society for his contributions in computational mechanical metallurgy. He was Associate Editor for Philosophical Magazine, International Journal of Solids and Structures, and now for the Journal of the Mechanics and Physics of Solids. He is the Editor in Chief of the Comptes Rendus Mécanique, an open diamond journal of the French Academy of Sciences. He was elected a member of the French Academy of Sciences in 2022.