Question:
(a) A perfect crystal of copper is tensile tested. The crystal is oriented so that the direction perpendicular to its slip plane is at 28° relative to the tensile direction. Consider three possible slip directions (relative to the tensile direction) of 81°, 72°, and 62.5°. Prove which of these is most favoured.
(b) For this favoured direction, calculate the minimum shear stress required to initiate slip. Assume that this copper crystal plastically deforms beginning at a tensile stress of 2 MPa.