1. Materials and their applications

Question 1

What are the mechanical properties of materials?

Answer 1

• associated with how a material reacts to an external force
• compressive strength
• tensile strength
• bending strength
• shear strength
• torsional strength
• hardness
• toughness
• plasticity
• ductility
• malleability
• elasticity

Question 2

What is compressive strength?

Answer 2

ability to withstand being crushed or shortened by pushing forces

Question 3

What is tensile strength?

Answer 3

ability to resist stretching or pulling forces

Question 4

What is bending strength?

Answer 4

ability to resist forces that may bend the material

Question 5

What is shear strength?

Answer 5

ability to resist sliding forces on a parallel plane

Question 6

What is torsional strength?

Answer 6

ability to withstand twisting forces from applied torque or torsion

Question 7

What is hardness?

Answer 7

ability to resist abrasive wear such as scratching, surface indentation or cutting

Question 8

What is toughness?

Answer 8

ability to absorb impact force without fracture

Question 9

What is plasticity?

Answer 9

ability to be permanently deformed and retain the deformed shape

Question 10

What is ductility?

Answer 10

ability to be drawn out under tension, reducing the cross-sectional area without cracking
(e.g. stretching a material into a wire)

Question 11

What is malleability?

Answer 11

ability to withstand deformation by compression without cracking

• malleability increases with a rise in temperature

Question 12

What is elasticity?

Answer 12

ability to be deformed and then return to the original shape when the force is removed

Question 13

What are the physical properties of materials?

Answer 13

• associated with the actual structure of the material
• density
• fusibility
• magnetism
• corrosion/degradation resistance

Question 14

What is density?

Answer 14

mass of a material in a standard volume of space

Question 15

What is fusibility?

Answer 15

ability of material to be fused or converted from a solid to a liquid or molten state, usually by heat
- good fusibility is an essential property for a metal being cast

Question 16

What is magnetism?

Answer 16

the natural force between objects that causes the material to attract iron or steels

Question 17

What is corrosion/degradation resistance?

Answer 17

ability of material to withstand environmental attack and decay

Question 18

What are electrical properties?

Answer 18

• electrical conductor
• electrical insulator

Question 19

What is an electrical conductor?

Answer 19

allows the flow of electrical current through the material
- a good conductor gives very little resistance to the flow of charge

Question 20

What is an electrical insulator?

Answer 20

does not allow the flow of electricity through the material

Question 21

What are thermal properties?

Answer 21

• thermal conductor
• thermal insulator
• thermal expansion

Question 22

What is a thermal conductor?

Answer 22

• allows transfer of heat energy through the material
• material with higher thermal conductivity allows the transfer of heat to occur quickly across the material

Question 23

What is a thermal insulator?

Answer 23

prevents the transfer of heat through the material

Question 24

What is thermal expansion?

Answer 24

the increase in material volume in response to heat input

Question 25

What are optical properties?

Answer 25

• opaque
• translucent
• transparent

Question 26

What is opaque?

Answer 26

prevents light from travelling through

Question 27

What is translucent?

Answer 27

allows light through, but diffuses the light so that objects appear blurred
- e.g. frosted glass

Question 28

What is transparent?

Answer 28

allow light to pass through easily, meaning you can see clearly through the material