고체역학 (Gere) — Stresses in Beams (Advanced Topics): Problem R-6.5

R-6.5 A composite beam of aluminum (\(E_a = 72 \text{ GPa}\)) and steel (\(E_s = 190 \text{ GPa}\)) has a width \(b = 25 \text{ mm}\) and heights \(h_a = 42 \text{ mm}\) and \(h_s = 68 \text{ mm}\), respectively. A bending moment is applied about the \(z\) axis resulting in a maximum stress in the aluminum of \(55 \text{ MPa}\). The maximum stress in the steel is approximately: (A) 86 MPa (B) 90 MPa (C) 94 MPa (D) 98 MPa