Project ForgeMachine Design
Design Against Static Load
GATE 2018
Medium
If the wire diameter of a compressive helical spring is increased by 2% (mean coil diameter and number of coils unchanged), the change in spring stiffness (in %) is _____ (correct to two decimal places).
8.25 %(± 0.25 accepted)
Explanation
Spring stiffness k = Gd⁴/(8D³n) ∝ d⁴ for fixed D and n. A 2% increase in d gives k'/k = 1.02⁴ ≈ 1.0824, i.e., an 8.24% increase.
Source: GATE ME 2018 Session 1 (Set 1) (2018)
This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.