# Aerospace Materials and Processes Questions and Answers – Aircraft Materials – Tension Testing – Yield Strength and Yield Point Determination

«
»

This set of Aerospace Materials and Processes online quiz focuses on “Aircraft Materials – Tension Testing – Yield Strength and Yield Point Determination”.

1. Tension test can give us the yield strength of a material.
a) True
b) False

Explanation: Tension testing can give us crucial information regarding the properties of a material. Apart from the ultimate tensile strength, the yield strength and reduction in area can be determined through tension testing.

2. Tension testing must be accurate within a percentage of ___________
a) +2%
b) +1%
c) +3/2 %
d) 21%

Explanation: The process of tension testing must adhere to certain conditions to assure its validity. One of the conditions is the range of accuracy of the testing machine. The percentage within which the accuracy should be present is 3/2%.

3. The yield strength of a material is ___________
a) the proof stress of a material
b) the strain where the strength of material fails
c) the elongation
d) the particular stress where a material shows specified elongation under a load

Explanation: The yield strength of a material is the particular stress where a material shows specified elongation under a load. The elongation of a material is the change in length before being affected by stress to after.

4. There is often no choice between the two methods of determination of yield strength available, as it is predetermined.
a) True
b) False

Explanation: Usually, the preferred method of determining yield strength can be used. It is not fixed. The two methods typically used to find the yield strength are set method and extension under load method.

5. What does length ‘AC’ in the diagram represent?
a) Yield gage
b) Yield strength
c) Set
d) Yield point

Explanation: The length AC is called the ‘set’ or gage length percentage. The graph represents yield strength determination through the set method. The yield strength is represented at the point ‘B’ in the graph.

6. The extension under load method is easier to use in finding yield strength because ___________
a) no necessity to plot a curve
b) it is not easier
c) it is the only method available
d) randomness

Explanation: The extension under load method is used much more than the set method. This is due to the fact that the former method does not require the plotting of a curve to find the yield strength of a material.

7. The second part of specified extensions in the extensions under load method typically involves adding an elongation of ____ inch per inch of gage length.
a) 0.2
b) 2.02
c) 0.02
d) 0.002

Explanation: The extensions under load method consists of two sections. First is elongation depending on the modulus of elasticity of object and expected yield strength and the second involves adding an extra elongation of 0.002 inch per inch gage length.

8. If the expected yield strength of a material is 50,000 pounds per square inch and modulus of elasticity is 10,000, what is the normal elongation of the material?
a) 50,000,000 inch per inch gage length
b) 5 inch per inch gage length
c) 50 inch per inch gage length
d) 5 inch per inch gage length

Explanation: The formula of normal elongation is given by = $$\frac{Expected \, yield\, strength}{Modulus \,of\, elasticity}$$
= $$\frac{50,000}{10,000}$$
= 5 inches per inch gage length.

9. The modulus of elasticity of steel is ____________ pounds per square inch.
a) 6,500,000
b) 10,000,000
c) 30,000,000
d) 1000,00

Explanation: The modulus of elasticity of a material is used in determining the normal elongation of a material. The modulus of elasticity of steel is 30,000,000 pounds per square inch. For aluminium alloys, it is 10,000,000 Psi and for magnesium it is 6,500,000 psi.

10. What is the yield point of a material?
a) Change in the strain of a material
b) The ratio of proof stress to the area
c) The elasticity of a material
d) Point where there is a substantial increase in elongation without a rise in load

Explanation: A materials yield point is the point where there is a significant increase in the elongation without an increment in the load. The yield point of a material can be determined in two ways – the divider method, and drop of beam method.

11. To obtain consistent results in finding properties of materials, the specimen must be/have __________
a) no scratches
b) straightened
c) washed with methyl
d) bent

Explanation: For the experiment to work with the production of accurate results, the material must not contain scratches. It should not be straightened or bent as it will negatively affect the values of the experiment.

12. The yield point can be determined in _____________
a) wood
b) carbon
c) pure molybdenum
d) mild carbon steel

Explanation: The yield point is not present in all available materials. It is present in certain materials like Mild carbon steel and wrought iron. It does not exist in wood, pure carbon or pure molybdenum. There are two methods to determine the yield point of a material.

13. In which method is there usage of a pair of dividers?
a) Set method
b) Divider method
c) Drop of beam method
d) Dividend method

Explanation: There are two methods to determine the yield point of a material. One is divider method, and the other is drop of beam method. In that, drop of beam method uses a pair of dividers. Set method is a method of determination of yield strength.

14. The yield point of a material does not exist for those materials that have a _____________ region in that space of the stress-strain curve.
a) smooth
b) shift
c) turbulent
d) high

Explanation: The materials that have a sharp break in the yield point of the stress-strain curve tend to have a yield point. These are materials like wrought iron. Other materials have a smooth region in the place of the sharp break of yield point, hence do not have this property.

15. In which method of determination of yield point is the load applied uniformly on the beam?
a) Divider method
b) High beam method
c) Drop of beam method