고체역학 (Gere) — Stresses in Beams (Advanced Topics): Problem R-6.4

R-6.4 A bimetallic beam of aluminum (\(E_a = 70\text{ GPa}\)) and copper (\(E_c = 110\text{ GPa}\)) strips has a width of \(b = 25\text{ mm}\); each strip has a thickness \(t = 1.5\text{ mm}\). A bending moment of \(1.75\text{ N}\cdot\text{m}\) is applied about the \(z\) axis. The ratio of the maximum stress in the aluminum to that in the copper is approximately: (A) 0.6 (B) 0.8 (C) 1.0 (D) 1.5