A coil spring with squared and ground ends is to operate with a load that fluctuates between 90 and 180 lbs, during which the deflection is to vary by 1 in. We wish to use an available supply of steel spring wire having d = 200 in and a fatigue strength of 116 ksi. The wire is shot peened to achieve this fatigue strength. Allow for a 10% clash allowance and a 10% safety factor to achieve the highest possible natural frequency. G = 11.5 X 10 psi. Determine N, D, Li and the natural frequency. A coil spring with squared and ground ends is to operate with a load that fluctuates between 90 and 180 lbs, during which the deflection is to vary by 1 in. We wish to use an available supply of steel spring wire having d = 200 in and a fatigue strength of 116 ksi. The wire is shot peened to achieve this fatigue strength. Allow for a 10% clash allowance and a 10% safety factor to achieve the highest possible natural frequency. G = 11.5 X 10 psi. Determine N, D, Li and the natural frequency