PERFORMANCE TEST ON COIL SPRING - Computer Programming

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## Wednesday, March 30, 2011

PERFORMANCE TEST ON COIL SPRING

Ex.No. 7
Date :

AIM :

To determine the following properties of a coil spring.
1. Stiffness of the given coil spring.
2. Modulus of rigidity.

APPARATUS REQUIRED :
Spring testing machine, coil spring, vernier caliper.

PROCEDURE :

1.      The spring is placed centrally over the lower plate slowly rotate the plate handle.
2.      Measure the thickness of spring and calculate the number of turns.
3.      Measure the outer diameter and inner diameter of spring using vernier caliber.
4.      Keep the spring in such a way that top and bottom plate just touches the spring.
6.      Note the deflections reading on the gauge apply the load on the spring and note the deflection reading.
7.      Note the deflection while unloading and also get the average deflection.
8.      Plot the graph between load and deflection.
9.      The deflection of a spring is obtained from the help of the graph.

CALCULATION :

Formula,
Modulus of rigidity   G= [(64nWR3)/ (δd4)]   N/mm2
where,
W - Load applied in N
δ – Deflection in mm
R – Mean coil radius of given spring in mm
d – Diameter of the spring wire in mm
n – Number of turns in the given spring
Stiffness of the spring   k = (W/δ)      N/mm
Mean radius  R = [(do-t)/2]     mm
do – outer diameter
t – Thickness

RESULT :

Modulus of rigidity of spring =                      N/mm2
Stiffness of spring                   =                      N/mm

TABULATION :