A wood beam with cross-sectional dimensions 200 mm × 300 mm is reinforced on its sides by steel plates 12 mm thick (see figure). The moduli of elasticity for the steel and wood are E s = 190 GPa and E...

A wood beam with cross-sectional dimensions 200 mm × 300 mm is reinforced on its sides by steel plates 12 mm thick (see figure). The moduli of elasticity for the steel and wood are E_s
= 190 GPa and E_w
= 11 GPa, respectively. Also, the corresponding allowable stresses are

_s
= 110 MPa and

_w
= 7.5 MPa.

(a) Calculate the maximum permissible bending moment M_max
when the beam is bent about the z axis.

(b) Repeat part (a) if the beam is now bent about its y axis.

(c) Find the required thickness of the steel plates on the beam bent about the y axis so that M_max
is the same for both beam orientations.