Question

3. The stress required to operate a Frank-Read source was determined in lecture by means of balancing the dislocation line tension, but could instead be approximated by a simpler approach. Specifically, the energy increase accompanying the dislocation bowing could be approximated as that from increasing the dislocation line length as the source operates. (a) Calculate the change in dislocation line energy as the dislocation bows out from a straight segment to a semi-circle. (b) The average force (not force per unit length) on the dislocation is roughly the energy change divided by a displacement. Estimate the displacement over which the increase in energy takes place, and find the average force. (c) Given the equation relating the shear stress to the force per length on a dislocation, estimate the stress required to operate the Frank-Read source. Compare your answer with the result derived in lecture.

          3. The stress required to operate a Frank-Read source was determined in lecture by means of balancing the dislocation line tension, but could instead be approximated by a simpler approach. Specifically, the energy increase accompanying the dislocation bowing could be approximated as that from increasing the dislocation line length as the source operates.
(a) Calculate the change in dislocation line energy as the dislocation bows out from a straight segment to a semi-circle.
(b) The average force (not force per unit length) on the dislocation is roughly the energy change divided by a displacement. Estimate the displacement over which the increase in energy takes place, and find the average force.
(c) Given the equation relating the shear stress to the force per length on a dislocation, estimate the stress required to operate the Frank-Read source. Compare your answer with the result derived in lecture.

3. The stress required to operate a Frank-Read source was determined in lecture by means of balancing the dislocation line tension, but could instead be approximated by a simpler approach. Specifically, the energy increase accompanying the dislocation bowing could be approximated as that from increasing the dislocation line length as the source operates.
(a) Calculate the change in dislocation line energy as the dislocation bows out from a straight segment to a semi-circle.
(b) The average force (not force per unit length) on the dislocation is roughly the energy change divided by a displacement. Estimate the displacement over which the increase in energy takes place, and find the average force.
(c) Given the equation relating the shear stress to the force per length on a dislocation, estimate the stress required to operate the Frank-Read source. Compare your answer with the result derived in lecture.

Added by Chelsea C.

Question

Please give Ace some feedback