PPT Slide
Where is the shear strain rate and is the average dislocation velocity. Equation (11.5) is a type of transport equation that often occurs in physics.
It simply states that the strain rate is equal to the density of defects producing strain (dislocations) times the strength of each defect (the amount of strain associated with each defect), times the average velocity of the defects.
In Chapter 12 we shall show that an identical equation exists for describing electrical conduction. For electrical conduction we write