MCD Assignment $-$ Helical Compression Spring Design

$20$ points

Two Helical compression springs are arranged concentrically. The steel springs have a static

loading of $3$ kN $.$ If the two springs have the same loaded and unloaded length, a ratio of mean

diameters of $\frac{3}{5}$ and a ratio of wire diameters of $\frac{5}{9}.$ Do the following:

a$.$ Calculate the mean diameter of the outer spring if the inner spring has a mean

diameter of $30$ mm $.$

b$.$ Calculate the wire diameter of the inner spring if the outer spring has a wire

diameter of $9$ mm $.$

c$.$ If presetting was used, and the wire material is ASTM A$229($oil tempered$),$

calculate the allowable shear stress for each of the springs.

d$.$ If the total number of coils for the outer spring is $7$ and for the inner spring is $12$

calculate the spring constant for each spring.

e$.$ Calculate the deflection from the given load for each spring.

$10$ points

f$.$ Calculate the shear stress in each spring for the given load.