When an open coiled helical compression spring is subjected to an axial compressive load, the maximum shear stress induced in the wire is (where D = Mean diameter of the spring coil, d = Diameter of the spring wire, K = Wahl's stress factor, and W = Axial compressive load on the spring)

• A. (4WD/ πd3) × K
• B. (2WD/ πd3) × K
• C. (WD/ πd3) × K
• D. (8WD/ πd3) × K

Answer: (D)