Music wire extension spring has a wire diameter of 003in an

Music wire extension spring has a wire diameter of 0.03in, an outside coil diameter of 0.25 in, hook radii of r1=0.108 in and r2=0.09in and an initial tension of 1.2 lbf The number of body turns Nb=12.2 Find the factors of safety under a static load 4.9 lbf

2. Music wire extension spring has a wire diameter of 0.03 in, an outside coil diameter of 0.25 in, hook radii of r, o.108 in and r, 0.09 in and an initial tension of 1.2-lbf. The number of body turns N 12.2. Find the factors of safety under a static load 4.9-lbf. (30 points)

Solution

solution;

1)here spring with hook end is subjected to initial tension 1.2 lbf or 5.337 N and load of 4.9 lbf or 21.79962 hence total oad on spring is

F=fi+F1=5.337+21.7962=27.1332 N

2)here for spring ,spring index is

C=D/d=.25/.03=8.333

3)stress correction factor

Ks=(1+.5/C)=1.06

4)hence shear stress in spring is given as

t=Ks(8*D*F/pi*d^3)=1051.12 N/mm2

5)where shear stress is given for spring is

tall=.4 sut/Nf

where Nf=factor of safety is mostly taken as for static load to be 1.5

hence value of Sut on equating are

Sut=3942 N/mm2