Thermal, Hoop, and Torsional Stress

Question 1

What is thermal expansion?

Answer 1

When an object experiences length, area and volume changes because of a change in temperature.

Question 2

What is the magnitude of the thermal expansion changes dependent on?

Answer 2

The coefficient of thermal expansion.

Question 3

What dimensions are affected by the change in temperature

Answer 3

All dimensions are affected buy the change in temperature.

Question 4

What does an increase in temperature do in thermal expansion?

Answer 4

Will cause an increase in the dimensions.

Question 5

What does an decrease in temperature do in thermal expansion?

Answer 5

Will cause a decrease in the dimensions.

Question 6

How is the thermal strain handled?

Answer 6

The thermal strain is handled in the same manner as strain due to an applied load.

Question 7

What is the thermal strain equal to?

Answer 7

It is equal to the thermal coefficient of expansion multiplied by the difference in temperature.

Question 8

How is the thermal strain related to the thermal stress?

Answer 8

Hooke’s Law can be used.

Question 9

What kind of stress do cylindrical tanks experience under internal pressure?

Answer 9

Circumferential, longitudinal, and radial stresses.

Question 10

When is the radial stress component negligible for cylindrical thinned walls?

Answer 10

If the wall thickness is small.

Question 11

When can a tank be considered to be a thin walled tank?

Answer 11

If the ratio of the thickness to internal radius is less than approximately 0.1.

Question 12

When can a tank be considered to be a thick walled pressure vessel?

Answer 12

A cylindrical tank with a wall thickness to radius ratio greater than 0.1.

Question 13

How do tanks under external pressure usually fail?

Answer 13

Buckling.

Question 14

Can thin walled equations be used for tanks under external pressure?

Answer 14

No

Question 15

What is hoop stress?

Answer 15

Circumferential stress.

Question 16

Under what conditions is hoop stress under?

Answer 16

For thin walled tanks under internal pressure.

Question 17

What is the axial stress in cylindrical tanks?

Answer 17

Stress in the direction of its axial or longitudinal dimension.

Question 18

When is there axial stress in cylindrical tanks?

Answer 18

When the cylindrical tank is closed at the ends..

Question 19

What are the principal stresses in tanks?

Answer 19

The hoop and axial stresses.

Question 20

Under what condition are the hoop and axial stresses the principal stresses?

Answer 20

For pressure vessels when internal pressure is the only loading.

Question 21

When is the stress in the outside surface zero?

Answer 21

It is zero for three dimensional shells.

Question 22

What is the largest shear stress in three dimensions?

Answer 22

Half the hoop stress.

Question 23

What is the orientation of the shear stress on three dimensional tanks?

Answer 23

45 degrees to the surface.

Question 24

Is there a difference with direction in the surface or tangential stress for thin walled spherical tanks?

Answer 24

It is the same in all directions because of symmetry.

Question 25

What is Lame’s solution?

Answer 25

This method shows that the radial and tangential stresses vary with location within the tank wall.

Question 26

What are the principal stresses in thick walled pressure vessels?

Answer 26

At every point in the cylinder, the tangential, radial, and longitudinal stresses.

Question 27

When is it not necessary to use the combined stress equations?

Answer 27

in the absence of an external torsional shear stress.

Question 28

Where do the maximum radial, tangential and shear stresses occur?

Answer 28

At the inner surface for both internal and external pressurization.

Question 29

What kind of stresses does thick walled cylinder with internal pressurization experience?

Answer 29

Radial, tangential and axial.

Question 30

What kind of stresses does thick walled cylinder with external pressurization experience?

Answer 30

Tangential and radial.

Question 31

What is torsion?

Answer 31

When a shaft experiences shear stress

Question 32

What is the angle of twist?

Answer 32

If a shaft carries a torque.

Question 33

What is the angle of twist units?

Answer 33

It is found in radians and must be converted to degrees.

Question 34

How does the shear stress act due to torsion in thin walled non circular shells?

Answer 34

Around the perimeter of the tube.

Question 35

Is the shear stress proportional to the distance from the centroid of the cross section for thin walled shells under torsion?

Answer 35

No

Question 36

What is the shear flow?

Answer 36

Is the shear per unit length of the centerline path.

Question 37

Is the shear flow around the shell constant?

Answer 37

Yes whether the wall thickness is constant or variable.