Consider a long steel bar under tensile stress due to forces F acting at the edges along the length of the bar. Consider a plane making an angle with the length. What are the tensile and shearing stresses on this planet?
a) for what angle is the tensile stress a maximum?
b) for what angle is the shearing stress a maximum?
a) Tensile stress = normal forces to the surface of plane F/ area
A = area of cross-section which is perpendicular to the bar
A’ = the area of the plane cut along aa’ of the cross-section
The force perpendicular component along A or
Tensile stress =
For the max value, sin θ should be equal to 1. Hence,
b) Shearing stress = forces along the plane F/ area =
for shearing stress to be maximum,
which gives us