Investigate the elastic behaviour in a spring placed under a positive load (tension) and to calculate it's Spring Response.

The spring was then placed in a Lloyd's Tensile machine and extended by 5mm increments. The corresponding load values were noted. The experimental process was repeated until the extension reached 30mm. The extension was then reduced in 5mm stages back down to 0. At each interval the load values were recorded. The findings were tabulated and a graph was plotted for load vs extension.

Results:

Number of coils = 18

Wire diameter = 0.0034 m

Coil diameter = 0.044 m

Table 1 Extension Spring results

LOADING

UNLOADING

Load /N

Extension /mm

Load /N

Extension /mm

0

0

0

0

4.8

5.096

5.4

5.956

9

0.28

0.8

2.08

3.8

5.21

5.6

7.79

7.9

20.09

20.5

23.84

21.5

25.02

26.3

30

Graph 2 represents the load /N against the extension /mm of the spring. (See attached sheet)

The slope of the graph is a measure of the Spring Response and the gradient was found to be 876 Nm-1

By calculation using S = G.d4

8.n. D3

Where S = Spring Response

G = Modules of Rigidity = 79.3 Gpa

d = Wire Diameter

D = Coil Diameter

n = Number of Coils

(79.3 X109 X 0.00344)

S = ---------------- = 864 Nm-1

(8 X 18 X 0.0443)

Conclusion:

The results obtained from the graphical method give a good approximation of the Spring Response. The errors occurring in this experiment are from the measurements of the wire diameter.

By Yousuf Rahmaan