Question
14. (a). A tensile test was conducted on a mild steel rod The following data was obtained from the test Diameter of stcel rod=12.5m Length of the rod=200mm Extension under load of 35KN=0.28 Maximum load=58.5KN Total extension=68.7mm Diameter of rod at failure=7.35mm Determine: hat (1) The value of the Young's modulus of elasticity; ii The maximum stress; iii. The percentage reduction in area; iv.The percentage elongation. (10 marks)
Solution
4.3
(181 Votos)
Josephina
Mestre · Tutor por 5 anos
Resposta
Let's go through each part of the problem step-by-step:### i. Young's Modulus of ElasticityYoung's modulus (E) is given by the formula:
Where:-
is the stress,-
is the strain.First, we need to calculate the stress (
):
Where:-
is the force (load),-
is the cross-sectional area.Given:- Diameter of the rod = 12.5 mm,- Length of the rod = 200 mm,- Maximum load = 58.5 kN.The cross-sectional area
is:
The stress
is:
Next, we calculate the strain
:
Where:-
is the total extension,-
is the original length.Given:- Total extension = 68.7 mm,- Original length = 200 mm.The strain
is:
Now, we can calculate Young's modulus
:
### ii. Maximum StressThe maximum stress is already calculated in the first part:
### iii. Percentage Reduction in AreaThe reduction in area is given by the difference between the original area and the area at failure:
Where:-
is the original area,-
is the area at failure.Given:- Original area
,- Diameter at failure = 7.35 mm.The area at failure
is:
The reduction in area
is:
The percentage reduction in area is:
### iv. Percentage ElongationThe percentage elongation is given by:
Where:-
is the total extension,-
is the original length.Given:- Total extension = 68.7 mm,- Original length = 200 mm.The percentage elongation is:
### Summaryi. Young's Modulus of Elasticity: