고체역학 (Beer) — Pure Bending: Problem 4.162

4.162 For the curved bar and loading shown, determine the stress at points A and B when \( r_1 = 40 \text{ mm} \). From Fig. P4.161 and P4.162: Bending moment: \( M = 75 \text{ N}\cdot\text{m} \) Cross-section: Rectangular, width \( b = 30 \text{ mm} \), height \( h = 20 \text{ mm} \) Point A: Inner surface (\( r = r_1 \)) Point B: Outer surface (\( r = r_2 \))