[SY-C2] Anisotropic and non-symmetric continuum dislocation dynamics
Continuum dislocation dynamics (CDD) is a recently developed crystal plasticity theory based on the kinematics and kinetics of dislocations as moving flexible lines in crystals. In CDD the dislocation state may be characterized in varying levels of details by considering alignment tensors of different order [1]. Constitutive laws for the lowest level CDD theory yield microscopic stresses which determine the average dislocation velocity. Such a constitutive law was recently derived for the lowest order CDD variant [2] from an energy functional.
In the lowest order theory, the average dislocation velocity is assumed to be independent of dislocation character and orientation. However, edge and screw dislocations may have different mobilities, which requires the consideration of anisotropic dislocation velocities. Moreover, two recent papers on continuum modelling of simplified systems of straight parallel edge dislocations found a new microscopic stress contribution which is related to a possible asymmetry between the average velocities of edge dislocations of opposite sign [3,4].
In the current talk we show how the kinematic equations may consider asymmetric and anisotropic dislocation velocities and how these modified evolution equations yield new microscopic stress contributions in the driving force for thermodynamically consistent CDD theory. The influence of selected terms is highlighted in small example problems.
References
[1] T. Hochrainer, 2015. Philos. Mag., 95(12), 1321-1367.
[2] T. Hochrainer, 2016. J. Mech. Phys. Solids 88, 12-22.
[3] I. Groma, M. Zaiser and P. D. Ispánovity, 2016. Phys. Rev. B, 93(21) 214110.
[4] P.-L. Valdenaire, Y. Le Bouar, B. Appolaire and A. Finel, 2016. Phys. Rev. B, 93(21) 214111.
In the lowest order theory, the average dislocation velocity is assumed to be independent of dislocation character and orientation. However, edge and screw dislocations may have different mobilities, which requires the consideration of anisotropic dislocation velocities. Moreover, two recent papers on continuum modelling of simplified systems of straight parallel edge dislocations found a new microscopic stress contribution which is related to a possible asymmetry between the average velocities of edge dislocations of opposite sign [3,4].
In the current talk we show how the kinematic equations may consider asymmetric and anisotropic dislocation velocities and how these modified evolution equations yield new microscopic stress contributions in the driving force for thermodynamically consistent CDD theory. The influence of selected terms is highlighted in small example problems.
References
[1] T. Hochrainer, 2015. Philos. Mag., 95(12), 1321-1367.
[2] T. Hochrainer, 2016. J. Mech. Phys. Solids 88, 12-22.
[3] I. Groma, M. Zaiser and P. D. Ispánovity, 2016. Phys. Rev. B, 93(21) 214110.
[4] P.-L. Valdenaire, Y. Le Bouar, B. Appolaire and A. Finel, 2016. Phys. Rev. B, 93(21) 214111.