Project title: Fundamentals of dislocations in motion
Supervisors: Prof. D. Dini, Dr. D.S. Balint and Prof. A.P. Sutton FRS
Collaborator: Dr. B. Gurrutxaga-Lerma
Our understanding of dislocation mobility - quantifying the relationship between the force on a dislocation and its resulting velocity - is largely based on experiment. However, the validity of mobility laws extracted from this work breaks down for fast travelling dislocations moving with speeds comparable to the speed of sound in the medium. In the last 20 years, large-scale non-equilibrium molecular dynamics simulations have been used to simulate qualitative mobility laws for fast travelling dislocations. However they have contributed little to our fundamental understanding of dislocation mobility in this regime. Ultimately, a physically motivated theory of dislocation mobility in the pure-glide regime in good quantitative agreement with existing simulation data is the aim of this project. This could shed light on the phenomenology associated with these fast travelling dislocations. Debate on this topic has been ongoing for over half a century and is problematic given that in this regime, the usual approximations by which elasticity theory is linearised are violated and the quasi-static approximation no longer holds.
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B. Gurrutxaga-Lerma, D.S. Balint, D. Dini, D.E. Eakins, A.P. Sutton, Proc. R. Soc. A, 469 2156 (2013)