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1. What is stress?

The internal resistance offered by a body per unit area against

deformation is known as stress. The unit of stress is N/mm2 or

N/m2 When an external force acts on a body, the body tends to

undergo deformation. Due to cohesion between molecules the

body resist the force. This resistance offered by the body is known

as strength of material

2. What is tensile stress?

Tensile stress: The resistance offered by a body per unit area

when it is subjected to a force which acts away from its point of

application is called tensile stress.

3. What is compressive stress?

Compressive stress: The resistance offered by a body per unit

area when it is subjected to a force which acts towards its point of

application is called compressive stress.

4. What is shear stress?

Shear Stress:The resistance offered by a body per unit area

when the applied load on the body consists of two equal and

opposite forces not in the same line is called shear stress.

5. What is strain?

when a body is subjected to some external force, there is

some deformation of the body. The ratio of change of dimension of

the body to the original dimension is known as strain. It has no

unit.

6. What is Tensile strain?

The length of the bar increases by an amount under the action of

external force P then

7. What is compressive strain?

The length of the bar decreases by an amount under the action of

external force P then ** Compressive Strain =**

8. What is Shear strain?

The distortion produced by shear stress on an element or

rectangular block is known as shear strain. It can also be defined

as the change in the right angle.

9. What is volumetric strain?

The ratio between the change in volume and the original volume

is known as volumetric stain.

10. Define True stress and True Strain

The true stress is defined as the ratio of the load to the cross

section area at any instant.

11. Define Hooke’s law?

Within the elastic limit, when a body is loaded, then stress

induced is proportional to the strain. This is called as Hook’s law.

12. What is linear strain?

The ratio of increase or decrease in length to the original

length is called as linear strain.

13. What is lateral strain?

The ratio of increase or decrease in lateral dimensions to

the original lateral dimensions is called as lateral strain.

14.What are the types of elastic constants?

1)Modulus of elasticity or Young’s modulus

2)Modulus of rigidity or shear modulus

3)Bulk modulus

15. What is poison’s ratio?

When a member is stressed with in elastic limit, the ratio of

lateral strain to its corresponding linear strain remains constant

throughout the loading. This constant is called as poison’s ratio. It

is the ratio of lateral strain to longitudinal or linear strain.

16. What is the inter relationship between the three constants? Where, E = Young’s modulus in N/mm2

K = Bulk modulus in N/mm2

G = Modulus of rigidity in N/mm2 μ Poisson’s ratio

17. Define bulk modulus?

When a body is stressed the ratio of direct stress to the

corresponding volumetric strain is constant with in elastic limit.

This constant is called as bulk modulus. Bulk modulus is the ratio

of direct stress to volumetric strain.

18. Define modulus of elasticity?

Modulus of elasticity is the ratio of stress to strain.

19. Define factor of safety?

Factor of safety is defined as the ratio of ultimate stress to

the working stress (permissible stress).

20. What is elasticity?

The deformation produced due to the application of

external load disappears completely with the removal of the load.

This property of the material is called as elasticity.

21. What is elastic limit?

Elastic limit is the limiting value of the load up to which the

material returns back to its original position. Beyond this load, the

material will not return back to its original position.

22. What are thermal stresses and strain?

Whenever there is increase or decrease in the temperature of the

body, the body tends to expand or contract. If this deformation is

prevented, some stresses are induced in the body, these stresses

are called as thermal stresses or temperature stresses. The

corresponding strains are thermal strain or temperature strains.

Thermal stress is σt =α T E where α is co-efficient of linear

expansion, T is rise in temperature E is young’s modulus

23. If the values of E and μ for an alloy body is 150 GPa and 0.25

respectively, find out the value of bulk modulus for the alloy?

24. Differentiate between Ultimate stress and working stress?

Ultimate stress is the maximum value of stress up to which

the material withstand its failure. Working stress is the maximum

stress allowed to setup in a material in actual practice.