PPT Slide
Because dislocations can glide only under the effect of shear stresses, these shear stresses have to be determined.
In uniaxial tensile and compressive test ( the most common tests), one has to determine mathematically the shear component of the applied stress acting on the plane in which slip is taking place.
Figure 11-15 shows a crystal with a normal cross-sectional area A upon which a tensile load acts, generating a uniaxial stress P/A.