Materials Assignment-
Aims:
The aim of this practical is to carry out tensile tests on selected metal and polymer samples with a view to understanding stress versus strain behaviour, Hooke's Law, Young's modulus, ultimate stress, yield, ductile and brittle behaviour and structure-property relationships. You will compareyour tensile data with that published in literature.
1. OUTLINE OF YOUR REPORT
1. Aims
2. Introduction
Define:
a) Hooke's Law,
b) Young's Modulus,
c) Ultimate Stress,
d) Yield stress,
e) Breaking stress,
f) Breaking strain,
g) Ductile Material,
h) Brittle Material
Analysis of your results-
a) Extract the Young's modulus from the graphs. Young's modulus for each sample is calculated during the practical by using the straight line fitting within the software.
b) Read Ultimate stress (tensile strength), yield stress, breaking stress, breaking strain and percentage elongation at break (if the sample is broken).
c) For metal samples if there is no clear yield point determine the 0.2% offset yield stress.
d) Tabulate Young's modulus, Ultimate stress (tensile strength), Yield stress , 0.2% offset yield stress, breaking stress, breaking strain, percentage elongation at break for all the samples you tested.
e) Include values for the above from literature for comparison on the same table
f) Comment on the results and possible sources of error.
g) Comment on the ductile versus brittle behavior from your results. Which samples exhibited ductility and which ones failed in a brittle manner?
h) Comment on the strength of materials, compare and contrast them. Compare metals and polymers with respect to their general tensile behaviour. Give reasons for the observed behavior.
INTERPRETATION OF DATA-
You have built the majority of the tension testing machine, but much of the instrumentation is still being assembled. To test the machine, you perform a test on a steel specimen with known properties. The machine provides you with the given load data, and you manually record the lengths between the marks on the specimen at each point using an extensometer to obtain the table of data shown below.
|
L (mm)
|
50.03
|
50.06
|
50.89
|
52.03
|
53.34
|
54.92
|
57.12
|
62.13
|
64.51
|
66.91
|
68.59
|
69.04
|
|
P (kN)
|
15.61
|
31.54
|
35.01
|
39.28
|
43.77
|
48.04
|
52.36
|
55.03
|
52.49
|
48.09
|
43.64
|
41.90
|
Use these results to plot the stress versus strain curve for the above sample and determine:
1) Why is stress versus strain diagram is preferable to force versus extension diagram?
2) Plot the above data using computer
3) Yield stress
4) Yield strain
5) Ultimate stress (tensile strength)
6) Young's modulus
7) Modulus of resilience
C. Using the information in the following graph of a\the sample with a gauge length of 50 mm and diameter 10 mm.
1) If the sample was strained to a value of 0.0035 and released what would be the elastic recovery?
2) Given that the Poisson's ratio of this material is 0.29, if we applied a stress of 300 MPa, what would be change in its diameter?
3) Using the graph below evaluate the approximate Modulus of Resilience of this material.
Attachment:- MIBT Assignment.rar