Mechanical Properties

Question 1

What provides the cohesive forces necessary to produce the solid state.

Answer 1

Chemical Bonds

Question 2

Chemical Bonds provide what?

Answer 2

the cohesive forces necessary to produce the solid state.

Question 3

In solids, atomic and molecular movement is restricted to?

Answer 3

Thermal Vibration

Question 4

If the temperature of a solid is raised, the amplitude of vibration increases and will eventually…

Answer 4

Disrupt the order of the structure.

Question 5

to disrupt the order of the structure in a solid, we need to.

Answer 5

Increase vibration by raising the temperature.

Question 6

There’s tendency for high melting point metals to have high

Answer 6

Young’s Moduli

Question 7

Young’s Modulus is related to…

Answer 7

The strength of the chemical bond

Question 8

What are the assumptions to Griffith’s theory of fracture

Answer 8

Hooke’s law is obeyed up to fracture point

All stressed solids store strain energy

All surfaces have an associated energy characteristic of the material

The process of the fracture can be considered a conversion of stored strain energy to surface energy

Question 9

Materials which fail in a brittle manner often contain strong…

Answer 9

Chemical Bonds.

Question 10

Ceramics are normally found to be extremely weak in their

Answer 10

Bulk Form

Question 11

What are the defects that can attribute towards weakness in a bulk material (3)

Answer 11

Cracks
Holes
Steps

Question 12

What do the Stress concentrators (Cracks, Holes, Steps) subject a components surface to

Answer 12

Stress connectors breakdown the chemical bonds at the crack tip and are subjected to stress will in excess of the average stress.

Question 13

The degree of stress concentration is

Answer 13

proportional to the crack length

Question 14

The magnitude of stress concentration was first calculated for an..

Answer 14

Elliptical hole by Inglis in 1913.

Question 15

Stress concentration alone is insufficient to initiate fracture. for crack propagation to occur, two conditions must be fulfilled.

Answer 15

The stored energy released must exceed the energy needed to create the fracture stress.

There must be a molecular or atomic mechanism by which this energy transformation can take place.

Question 16

What is more important than stress concentration to determine a materials response to stress.

Answer 16

The critical crack length.

Question 17

What is the greatest safe guard against brittle fracture.

Answer 17

having a very high value of W

Question 18

The process of slip in which adjacent layers of atoms move relative to each other is known as…

Answer 18

The mechanism of plastic deformation in metals.

Question 19

The mechanism of plastic deformation in metals, is the process of what.

Answer 19

slip in which adjacent layers of atoms move relative to each other.

Question 20

The shear stress necessary to cause slip may be calculated from a knowledge of

Answer 20

the strength of the metallic bond.

Question 21

Metal crystals are perfect arrays of

Answer 21

Metallic Ions

Question 22

Linear defects are commonly known as

Answer 22

Dislocations

Question 23

Dislocations are commonly known as

Answer 23

Linear Defects

Question 24

Plastic deformation in metallic crystals are produced by

Answer 24

The movement of dislocations.

Question 25

The movement of dislocations in metallic crystals produce

Answer 25

Plastic deformation