고체역학 (Gere) — Stresses in Beams (Advanced Topics): Problem 6.2-11

6.2-11 A bimetallic beam used in a temperature control switch consists of strips of aluminum and copper bonded together as shown in the figure, which is a cross-sectional view. The width of the beam is 25 mm, and each strip has a thickness of 2 mm. Under the action of a bending moment \( M = 2 \text{ N}\cdot\text{m} \) acting about the \( z \) axis, what are the maximum stresses \( \sigma_a \) and \( \sigma_c \) in the aluminum and copper, respectively? (Assume \( E_{Al} = 72 \text{ GPa} \) and \( E_{Cu} = 115 \text{ GPa} \).)