Topic: Machine Design
A round wire helical spring is loaded by the axial force. The maximum shear stress in the wire cross section will be at
- A. Outer fibre
- B. Inner fibre
- C. Center of the cross section
- D. Both outer and inner fibres
Answer: B. Inner fibre
Explanation: In a helical spring, the direct shear stress and the torsional shear stress are additive on the inner edge of the coil. Additionally, the curvature effect (accounted for by the Wahl factor) further concentrates the stress at the innermost fiber.