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adhishm / dd2d_Matryoshka

A set of classes defining the behaviour of crystalline defects, with the final goal of carrying out dislocation dynamics simulations in two dimensions.
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CRSS validation for dislocations #14

Closed adhishm closed 11 years ago

adhishm commented 11 years ago

For a dislocation, the force experienced due to an applied stress is given by the Peach-Koehler equation.

However, for the dislocation to move, the total shear stress on it must be greater than the critical resolved shear stress (CRSS). As can be seen from the final expression of the Peach-Koehler force, the shear stresses (expressed in the dislocation's co-ordinate system) are s12 and s23, for the edge and screw components, respectively.

The question then arises: What criterion for CRSS (which is a single number) should be applied?

adhishm commented 11 years ago

Perhaps it should be a combined criterion: sqrt( b1^2 + b3^2 ) * CRSS < sqrt( (b1_s12)^2 + (b3_s23)^2 )

adhishm commented 11 years ago

There should be no CRSS for the glide of dislocations. It is necessary only for their creation.

Ref: Dislocations, J Friedel, Pergamon Press, 1964