For a compression spring with 2.2 inch OD was made from music wire with 0.2-inch diameter. The spring is peened with squared and ground ends. The spring is to be used in a machine by compressing it from free length of 6 inch into a solid length of 3 inch. Determine: (a) its spring rate
(b) the static factor of safety when compressed to solid length
(c) the fatigue factor of safety when repeatedly cycled from free length to solid length. Use Modify Goodman-Zimmerli fatigue failure criterion