The beam is subjected to a bending moment M = 400 N‐m about the z ’ axis, which is a principal axis. The moment of inertia of the cross section about z ’ is I z ’ = 40E-8 m 4 : Determine the normal...

The beam is subjected to a bending moment
M
= 400 N‐m about the
z’ axis, which is a principal axis. The moment of inertia of the cross section about
z’ is
I<sub>z

’</sub>
= 40E-8 m⁴: Determine the normal stress at point
Q, which has coordinates
y’ = 0.0313 m,
z’ = 0.0179 m.

Suppose that instead of being applied about the principal axis
z’  as shown, the bending moment
M
= 400 N‐m is applied about the principal axis
y’  in a direction such that points of the cross section with positive
z’  coordinates are subjected to tensile stress. The moment of inertia of the cross section about the
y’ axis is
I_y’

= 160E-8 m⁴: Determine the normal stress at point
P, which has coordinates
y’ = 0.0313 m,
z’ = 0.0269 m.