A helical compression spring used for essentially static loading has d = 0.100 in., D = 0.625 in., N = 8, and squared and ground ends. It is made of ASTM A227 cold-drawn steel wire.
(a) Compute the spring rate and the solid height.
(b) Estimate the greatest load that can be applied without causing long-term permanent set in excess of 2 percent.
(c) At what spring free length will the load determined in part (b) cause the spring to become solid?