고체역학 (Beer) — Pure Bending: Problem 4.2

4.1 and 4.2 Knowing that the couple shown acts in a vertical plane, determine the stress at (a) point A, (b) point B. For Fig. P4.2: Bending Moment: \( M = 25 \text{ kip}\cdot\text{in.} \) Cross-section: Rectangular with two circular holes. Width: \( b = 4.8 \text{ in.} \) Height: \( h = 1.2 \text{ in.} + 1.2 \text{ in.} = 2.4 \text{ in.} \) Hole Radius: \( r = 0.75 \text{ in.} \) Point A: Top edge of the cross-section. Point B: Bottom-most point on the boundary of one of the holes.