고체역학 (Beer) — Introduction—Concept of Stress: Problem 1.2

1.2 Two solid cylindrical rods AB and BC are welded together at B and loaded as shown. Knowing that the average normal stress must not exceed 150 MPa in either rod, determine the smallest allowable values of the diameters \(d_1\) and \(d_2\). (Referencing Fig. P1.1 and P1.2 values from the image: Load at A = 60 kN to the left; Two 125 kN loads at B to the right; Length AB = 0.9 m; Length BC = 1.2 m)