Prof. Fionn Dunne
Imperial College London
PLENARY TALK TITLE: Slip, dislocations and stored energy in microstructurally-sensitive crack nucleation and growth
ABSTRACT: Short, microstructurally-sensitive crack growth in engineering alloys may contribute a significant fraction of fatigue life but is not yet fully understood. Nucleation site, crack path tortuosity and rates of initiation and growth remain key questions to address and solutions at the microstructural length scale could offer the potential of substantive improvement in safety-critical component design.
In this presentation, studies based on integrated small-scale experiment, high-resolution characterisation and discrete dislocation and crystal plasticity modelling will be presented to address the mechanistic bases of the above phenomena. Quantification of slip , lattice curvature and dislocation density , and stored energy  have provided insights in to strain localisation , crack nucleation site  and crack paths and propagation rates  in a range of engineering alloys. Recent work on the mechanistic drivers of short fatigue crack growth in HCP zirconium alloy is addressed in this presentation with in-situ EBSD and DIC characterisation combined with crack tip analysis and crystal plasticity modelling .
 Yongjun Guan, et al. Crystal Plasticity Modelling and HR-DIC Measurement of Slip Activation and Strain Localisation in Single and Oligo-crystal Ni Alloys under Fatigue. Intl. Jnl. Plasticity, 88, 70-88, 2017.
 Nikoletta Prastiti et al. Discrete dislocation, crystal plasticity and experimental studies of fatigue crack nucleation in single-crystal nickel. Intl. Jnl. Plasticity, 126, https://doi.org/10.1016/j.ijplas.2019.10.003, 2020.
 Zebang Zheng et al. The dislocation configurational energy density in discrete dislocation plasticity. Jnl. Mech. Phys. Solids. 129, 39-60, 2019.
 David Wilson et al. Microstructurally-sensitive fatigue crack growth in HCP, BCC and FCC polycrystals. Jnl. Mech. Phys. Solids. 126, 204-225, 2019.
 Yilun Xu et al. Microstructural fracture mechanics: stored energy density at fatigue cracks. Jnl. Mech. Phys. Solids. 146, 104209, 2021.
BIO: Fionn Dunne is Chair in Micromechanics and holds the Royal Academy of Engineering/Rolls-Royce Research Chair at Imperial. His research is in the fundamentals of deformation and failure particularly relating to hcp polycrystal and Ni alloys and includes experiment, characterisation, computational crystal plasticity and discrete dislocation plasticity. Applications include micro-deformation, fatigue crack nucleation, microstructure-sensitive crack growth, and polycrystal sonics for NDE.
He has published over 180 research papers and is co-author of Introduction to Computational Plasticity, OUP, 2005. He is a consultant to Rolls-Royce, a member of their Core Materials Working Group, a member of the MOD’s Research Programmes Group and was a Royal Society Industry Fellow with Rolls-Royce. He led the EPSRC programme grant Heterogeneous Mechanics in Hexagonal Alloys across Length and Time Scales, directed the Imperial Rolls-Royce Nuclear University Technology Centre, and currently Co-Directs the BIAM Centre for Materials. He is Honorary Professor with the Beijing Institute of Aerospace Materials, and is Emeritus Fellow of Hertford College Oxford. He was elected a Fellow of the Royal Academy of Engineering in 2010, was awarded the IoM3 Harvey Flower Prize (2016), and shared the 2017 Imperial President’s Award for Outstanding Research Team.