고체역학 (Gere) — Analysis of Stress and Strain: Problem 7.2-17

7.2-17 A simply supported beam is subjected to point load \( P \) at mid-span. The normal stress on an element at mid-span is known to be \( \sigma_x = 10 \text{ MPa} \). Determine the element stresses if it is rotated through angle \( \theta = -45^\circ \). Show these stresses on a sketch of an element oriented at that angle.