**THIN CYLINDERS, SPHERES AND THICK CYLINDERS**

1. List out the modes of failure in thin cylindrical shell due to an internal pressure.

i)Circumferential or hoop stress and

ii)Longitudinal stress

2. What do you mean by principal plane?

The planes which have no shear stress are known as principal planes.

3. What are assumptions involved in the analysis of thin cylindrical shells?

The material of the cylinder is homogeneous, isotropic and obeys Hook’s law.

i)The hoop stress distribution in thin cylinder is uniform over the cross section from inner to outer surface since the thickness of the cylinder is thin and

ii)Weight of fluid and material of the cylinder is not taken into account.

4. What are principal planes and principal stress one end is fixed and other end is free?

Principal stress: The magnitudes of normal stress, acting on a principal plane are known as

principal stresses. The plane which have no shear stress are known as principal planes.

5. Define Circumferential and Hoop stress.

A thin cylinder shell is subjected to an internal pressure, as a result of internal pressure, the

cylinder has tendency to split up into two troughs is called circumferential stress. The same cylinder shell,

subjected to the same internal pressure, the cylinder also has a tendency to split in to two pieces is known

as Hoop stress.

6. What is the use of Mohr’s circle?

It is used to find out the normal, tangential, resultant and principal stresses and their planes.

7. What are the planes along which the greatest shear stresses occurs?

Greatest shear stress occurs at the planes which is inclined at 45? to its normal.

8. What is the radius of Mohr’s circle?

Radius of Mohr’s circle is equal to the maximum shear stress.

9. In case of equal like principal stresses what is the diameter of the Mohr’s circle?

In case of equal like principal stresses what is the diameter of the Mohr’s circle is zero.

10. What is mean by position of principal planes?

The planes on which shear stress is zero are known as principal planes. The position of principal

planes are obtained by equating the tangential stress to zero.