고체역학 (Gere) — Axially Loaded Members: Problem 2.3-1

2.3-1 The length of the end segments of the bar (see figure) is 500 mm and the length of the prismatic middle segment is 1250 mm. Also, the diameters at cross sections A, B, C, and D are 12, 24, 24, and 12 mm, respectively, and the modulus of elasticity is 120 GPa. (a) Calculate the elongation of a copper bar of solid circular cross section with tapered ends when it is stretched by axial loads of magnitude 14 kN (see figure). (b) If the total elongation of the bar cannot exceed 0.635 mm, what are the required diameters at B and C? Assume that diameters at A and D remain at 12 mm.