고체역학 (Gere) — Analysis of Stress and Strain: Problem 7.2-13

7.2-13 Two steel rods are welded together (see figure); the seam is oriented at angle \(\theta = 50^\circ\). The stresses on the rotated element are \(\sigma_{x1} = 70 \text{ MPa}\), \(\sigma_{y1} = -83 \text{ MPa}\), and \(\tau_{x1y1} = -35 \text{ MPa}\). Find the state of plane stress on the element if it is rotated clockwise to align the \(x_1\) axis with the longitudinal axis of the rods.