in this notes , i couldn't understand that why there exists an angle (θp) where the shear stress (τx'y' ) becomes zero , (only normal stress acting )
is there any proof on this ?
for the second part , why when we find max shear stress , there's also average normal stress acting ?
The Attempt at a Solution
is the second diagram wrong ? when we find max shear stress , there should not be average normal stress acting ....[/B]