42. Frank Read Source of dislocations

Basics of Mechanical Behavior of Materials
This video deals with
1. Nucleation of dislocations
2. Multiplication of dislocations
3. Operation of a Frank-Read source

[@debalinabhattacharjee2505]

Lovely video.. ❤

[@nirajchawake]

Many many thanks

[@vincentjacquemain9121]

Good morning Sir, I have a question about the explanation of the Frank-read source. I clearly understood the principle. However, I wonder why the two sides of the dislocation loop are moving away (left part and right part of the loop) although they have the same burgers vector. Is it because their line vector is opposite? Thanks in advance! :)

[@nirajchawake]

Dear Vincent Dislocation tends to reduce energy, which can be accomplished by shortening its length (i.e., the dislocation line). Dislocations bend as a result of forces acting upon them. Even in this instance, the dislocation line bows due to the balance of forces acting upon it. When you cross a critical bowing dimension, in this case a semicircle, the dislocation will continue to bow if the force acting on it is sufficient. Remember that the Burgers vector is invariant, whereas the bowing occurs (or in other words, the dislocation moves) perpendicular to the tangent vector at every position (I guess that answers your question, but please try to visualize this). Now, when the dislocation line crosses the pinning points, they bow in such a way that there is a possibility of developing dislocation segments of opposing nature (in this case, positive and negative screws due to opposite tangent vectors); they attract and annihilate one another, creating a dislocation loop. I hope this helps.

[@surabhijaju2828]

Sir, Can you please provide the pdf notes?

[@nirajchawake]

Sure! Please email me on nchawake[at]iitk[dot]ac[dot]in