This set of Mechanical Behaviour Problems focuses on “Tension Test and Stress Strain Curve”.
1. What is the deformation per unit length?
Explanation: Deformation per unit length is known as strain. Stress is a load per unit area. Strain is expressed in fraction or in percent.
2. Ductility is indicated by _________
a) Percentage elongation
b) Percentage of expansion
c) Poisson’s ratio
Explanation: Ductility is calculated by percentage elongation and reduction in cross-sectional area. It is the ability of a material to undergo plastic deformation and it is opposite to brittleness.
3. If a bar is doubled in length, what will be the strain induced?
Explanation: Strain is given by the change in length divided by original length. Here on calculation, strain comes out to be 1.0.
4. Ductility is the opposite concept of _________
Explanation: Ductility is the measure of percentage elongation. Brittleness shows a material’s susceptibility to undergo brittle fracture. Hence it is the opposite of ductility.
5. What term is used for the ratio of lateral strain to linear strain?
a) Bulk modulus
b) Elastic modulus
c) Shear strain
d) Poisson’s ratio
Explanation: Ratio of lateral strain to linear strain is known as Poisson’s ratio. Modulus of elasticity is ratio of stress to strain. Bulk of modulus is mostly applied in liquids.
6. Material, if show identical properties in all directions, is said to be _________
Explanation: Directional properties are measured in terms of isotropy. If it shows properties identical in all directions, it is known as isotropic. Anisotropic is opposite of isotropic.
7. Which material has higher elasticity?
Explanation: Decreasing order of elasticity is steel > copper > rubber > glass. Elasticity is inversely proportional to strain developed within the material. That’s why steel is the most elastic of four.
8. _________ does not show linear stress strain relationship.
Explanation: Rubber is an elastic material. It does not exhibit linear stress strain relationship. Ceramics show higher elastic modulus.
9. The maximum stress up to which stress is proportional to strain is known as ________
a) Tensile stress
b) Compressive stress
c) Modulus of elasticity
d) Proportional limit
Explanation: The maximum stress up to which stress is proportional to strain is known as proportional limit. Modulus of elasticity is a ratio of stress to strain. Hooke’s law holds good in this limit.
10. Yield strength represents resistance against _________
b) Elastic deformation
d) Plastic deformation
Explanation: Yield strength represents materials’ resistance against plastic deformation. Rigidity shows resistance against elastic deformation. Stiffness is a measure of resistance against bending.
11. Strain hardening causes more deformation on less stress application.
Explanation: Strain hardening is an effect of dislocation multiplication. It causes a back stress development in material. So extra load is needed to apply.
12. Necking causes drop in load after an ultimate tensile point.
Explanation: Ductile metals show the drop in load after an ultimate tensile point. It is because of necking. It results in decrease in local cross section.
Sanfoundry Global Education & Learning Series – Mechanical Behaviour & Testing of Materials.
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