A helical compression spring, made of circular wire, is
subjected to an axial force, which varies from 4 kN to 5.5 Kn. Over
this range of force, the deflection of the spring should be
approximately 6 mm. The spring index can be taken as 4. The spring
has square and ground ends. The spring is made of patented and
cold-drawn steel wire with ultimate tensile strength of 1180 N/mm2
and modulus of rigidity of 82140 N/mm2 . The permissible shear
stress for the spring wire should be taken as 40% of the ultimate
tensile strength. Design the spring and calculate
(i) wire diameter;
(ii) mean coil diameter;
(iii) number of active coils;
(iv) total number of coils;
(v) solid length of the spring;
(vi) free length of the spring;
(vii) required spring rate; and
(viii) actual spring rate