Air Force Office of Scientific Research awards le Graverend Young Investigator Research Program grant

Jean Briac Le GraverendDr. Jean-Briac le Graverend, assistant professor in the Department of Aerospace Engineering at Texas A&M University, is one of 58 scientists and engineers who will receive approximately $20.8 million in grants from the Air Force Office of Scientific Research (AFOSR) through its Young Investigator Research Program (YIP).

Le Graverend, whose research goals are to predict the mechanical behavior and lifetime of materials at high temperature by means of a multi-scale approach combining experimental, theoretical and computational tools, was selected for his research on “Microstructural Instabilities in Single Crystal Metals for Extreme Environments.”

As the U.S. Air Force’s fleet continues to age, a greater portion of its budget will be required to ensure safe and effective operations beyond the design service life. For various military vehicles and platforms the recommended service life for safe operation is projected to increase by a factor of 1.5 to five. The high demand for safety and cost reduction culminates in the case of materials systems operating under extreme environments such as turbine blades made of Ni-based single crystal superalloys.

Turbine blades are used in the hot section of the engine and are therefore subjected to multiaxial high-temperature viscoplastic deformations due to both their complex geometry and their advanced design (internal cooling channels aimed to increase the exhaust-gas temperature during in-service operations). Uniaxial thermo-mechanical environments have already been shown to lead to microstructural instabilities such as phase transformations, microstructure gradients, and lattice rotations, which dramatically alter the mechanical properties.

This raises the question of how does in-service thermo-mechanical loading modify the kinetics of microstructural instabilities? The development of predictive deformation and damage models tailored for such extreme conditions are necessary and has recently been emphasized through the Digital Twin (DT) paradigm for future NASA and Air Force vehicles. The synergetic experimental and modeling approach developed in this project is a first step toward a fully integrated computational materials engineering.

The YIP is open to scientists and engineers at research institutions across the United States who received Ph.D. or equivalent degrees in the last five years and who show exceptional ability and promise for conducting basic research. The objective of the program is to foster creative basic research in science and engineering; enhance early career development of outstanding young investigators; and increase opportunities for the young investigator to recognize the Air Force mission and related challenges in science and engineering.

Le Graverend joined the department in 2014 after receiving a Ph.D. in materials science and engineering/aerospace from the National School of Mechanics and Aeronautics (ENSMA, Poitiers, France)/National Office for Studies and Aerospace Research (ONERA, Chatillon, France) in 2013 and doing a post-doc at Caltech in the aerospace department (GALCIT). He will receive $120,000 per year for the next three years from the AFOSR grant.