Unit 1

Question 1

What is stress?

Answer 1

Internal Resistance force per unit area.

Question 2

What is tension?

Answer 2

A structural member is said to be in tension when it is subjected to two equal and opposite pulls and the length increases and diameter decreases.

Question 3

What is compression?

Answer 3

If the structural member is subjected to two equal and opposite pushes and member tends to shorten/decrease in length and increase in diameter, the member is said to be in compression.

Question 4

What is strain?

Answer 4

Deformation per unit length.

Question 5

What is the unit of strain?

Answer 5

It is a dimensionless quantity.
It is taken positive if there is extension of the bar and negative if there is shortning.

Question 6

How many types of strain are there? Name them.

Answer 6

3
1. Longitudinal strain
2. Lateral strain
3. Volumetric strain

Question 7

Define Longitudinal strain.

Answer 7

It is defined as the ratio of change in length to the original length.
It is denoted by El.
El=∆l/l

Question 8

Define lateral strain.

Answer 8

It is defined as the ratio of change in diameter to the actual diameter.It is denoted by Ed.
Ed=-∆d/d

Question 9

What is the significance of -ve sign in the formula of lateral strain?

Answer 9

On applying the compression load on the bar, the diameter of the bar is increased and the length is decreased.

Question 10

Define Volumetric strain.

Answer 10

It is defined as the ratio of change in volume to the original volume .It is denoted as Ev.
Ev=∆V/V

Question 11

State Poisson’s ratio.

Answer 11

It is defined as the ratio of lateral strain to the longitudinal strain . It is denoted by ‘u’ (meu)or 1/m.
It’s value varies from -1 to 0.5.
And for most materials the value of Poisson ratio varies from 0 to 0.5.
Poisson ratio= - lateral strain/longitudinal strain.