# Aerospace Materials and Processes Questions and Answers – Aircraft Materials – Tension Testing

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This set of Aerospace Materials and Processes Multiple Choice Questions & Answers (MCQs) focuses on “Aircraft Materials – Tension Testing”.

1. What is the variation to which the tension testing machine must be sensitive?
a) 1/250 of the registered load
d) 1/200 of the registered load

Explanation: To obtain an accurate result, it is important for the test machine to be in appropriate condition. One of the important conditions is for a load being applied, the test machine must be sensitive to a variation of 1/250.

2. Which of the following can be obtained through a tension test?
a) Colour
b) Heat treatment
c) Ultimate tensile strength
d) Conductivity

Explanation: Tension testing can provide a lot of basic information about the property of the material being tested. Ultimate tensile strength is obtained through tension testing. It is the withstanding ability of a material to load. Tensile refers to bring pulled away.

3. During tension testing, the material must be held in _____________ alignment.
a) normal
b) axial
c) parallel
d) diabolical

Explanation: The material or the specimen should be positioned in true axial alignment. This is considered vital, especially since materials used in aircraft construction are thin. This will avoid damaging them.

4. The extensometer can be attached anywhere to the specimen.
a) True
b) False

Explanation: Extensometer is an instrument used to measure the change in the length of a material. It should not be placed anywhere to the specimen. It should be fixed at the gage marks of the specimen being tested in the testing machine.

5. The elastic limit of a material is _____________
a) the least amount of stress that can be held without permanent deformation
b) highest stress a material can experience without permanent deformation
c) average stress experienced by material in its lifeline.
d) strain on material

Explanation: The elastic limit is the highest stress that a material can withstand, without permanent deformation present when the stress is released completely. It is not the lowest amount of stress present.

6. In the tension testing experiment, while determining elastic limit, the increment, while the load is being increased, should not exceed ___________ % of the elastic limit in the ending.
a) 50
b) 7
c) 2
d) 3

Explanation: In the tension testing experiment, we can determine the elastic limit. Here the load is applied gradually in different points to determine the elastic limit. In the final part of the experiment, the load being increased should not exceed 3% of the elastic limit.

7. The tension testing machine (crosshead) should not cross a speed of ___________ inch per inch of the gage length per minute until the yield point.
a) 1/11
b) 2
c) 1/16
d) 2/5

Explanation: The crosshead of the tension testing machine has a certain advisable limit in speed it has to be operated up to. It is different until the yield point and after yield point till rupture. Until yield point it is 1/16 inch, yield point to rupture it is 1/2 inch. (Inch per inch)

8. It is possible to determine the proof stress in a way in which ___________ is determined.
a) elastic limit
b) yield point
c) stress
d) strain

Explanation: The proof stress of a material can be found or determined the same way the elastic limit can be determined. But, there are other methods through which the elastic limit can be found as well.

9. For a 4-inch gage length, crosshead speed of a machine should not exceed ___________ inch up to yield point.
a) 1/16
b) 1/4
c) 1/8
d) 1/6

Explanation: The speed which a crosshead should not exceed until yield point is 1/16 for one inch per inch gage length per minute.
For 4 inches, it is – $$\frac{1×4}{16}$$ = 1/4 inch.

10. What does ‘A’ represent in the diagram?

a) Stress meter
c) Gage length
d) Diameter of center

Explanation: ‘A’ is called the diameter of the centre of the specimen. Gage length is the horizontal distance marked on the specimen to signify the part that is under consideration. Stress meter is not present anywhere on the specimen.

11. A materials proof stress is the highest stress possible for it to tolerate without causing a permanent set of more than ___________ inch per inch the length of gage, after the total release of stress.
a) 5.1
b) 0.002
c) 0.0001
d) 0.1

Explanation: The highest possible stress a material can, without causing a permanent set of more than 0.00001 inch per inch of the gage length is called proof stress. This is after the total release of the stress.

12. Why must an accurate extensometer be used in reading a permanent set?
a) It is cheap
b) To obtain accuracy
d) It is unnecessary

Explanation: An extensometer must be used in reading the permanent set. An accurate extensometer is required to obtain the change in the property after the experiment is done, without any mistakes or problems with accuracy.

13. The proof stress of a material of 3 inches gage length is the highest stress it can withstand without a permanent set of above ___________ inch.
a) 0.0003
b) 0.21
c) 0.05
d) 0.004

Explanation: For a length of one inch, the permanent set of over 0.0001 inch withstanding is proof stress. For 3 inches length, it will be –
0.0001×3 = 0.0003 inches.
Hence, it is 0.0003 inches.

14. A materials proof stress is also referred to as ___________
a) elastic limit
b) yield limit
c) proportional limit
d) set method

Explanation: Proof stress of a material can also be called a proportional limit. The procedure to find the elastic limit and proof stress are similar, but the quantities are different. Yield limit can be found through tension testing, but it is not the same as proof stress.

15. The elongation of a material can be obtained through tension testing.
a) True
b) False