While calculating the stress induced in a closed coil helical spring, Wahl’s factor must be considered to account for
Option (A)
The curvature and stress concentration effect
Option (B)
Shock loading
Poor service conditions
Fatigue loading
Correct Option:
Question Solution:
Since the spring rod is bent into a curve, the shear stress on the inner surface is more then the shear stress developed on the outer surface. To take into account the curvature effect. Wahl’s correction factor may be applied and maximum shear stress can be calculated as follows.
tmax = kw(16WR/pd3)
Where kw is Wahl’s correction factor and is given by
Kw = {(4c-1)/4c-4) + (0.615/c)}
Where ‘c’ is the spring index