Lesson 1: Material Selection

Question 1

Describe hardness.

Answer 1

Hardness is a measure of how easily a material can be scratched or indented.

Question 2

What is the Ashby Diagram used for?

Answer 2

To compare the ratio between different properties of materials or classes of materials

Question 3

How is the suitability of a material determined in the materials selection table?

Answer 3

By calculating the sum of (IR x MR) for each class of material

Question 4

What is the purpose of the Materials Rating (MR) in the materials selection table?

Answer 4

To indicate the desirability of a material’s property for the application

Question 5

What is the purpose of the Importance Rating (IR) in the materials selection table?

Answer 5

To indicate how important a property is for application

Question 6

What is the main goal of material selection in product design?

Answer 6

To minimise cost while meeting product performance goals

Question 7

What is an important consideration when
designing a physical object?

Answer 7

Material selection is an important step in the process of designing any physical object

Question 8

Define durability

Answer 8

Durability is the combination of strength and toughness in a material

Question 9

What does thermal conductivity measure?

Answer 9

It measures how well a material can conduct heat

Question 10

What does electrical conductivity measure?

Answer 10

It measures how well a material can conduct electricity

Question 11

Explain elasticity

Answer 11

Elasticity is the ability of a material to return to its origincal form after a load has been applied and removed

Question 12

What is toughness?

Answer 12

Toughness is the ability of a material to withstand shock or sudden impact without breaking. Also a combination of strong and ductile.

Question 13

Describe the characteristics and properties of metals.

Answer 13

Good electrical and heat conductors, shiny appearance, good tensile and compressive strength, ductile, high toughness

Question 14

What is fatigue resistance?

Answer 14

It refers to how many repeated cycles of loading and onloading a material can withstand before it fails or breaks.

Question 15

How does high stiffness affect a material?

Answer 15

It makes a material hard to bend or stretch

Question 16

What is stiffness (Young’s modulus)?

Answer 16

It is also known as Young’s Modulus, is the ability of a material to resist deformation in repsonse to an applied force.

Question 17

Define compressive strength.

Answer 17

It is the ability of a material to withstand pushing or squeezing forces. (compression)

Question 18

Describe tension strength.

Answer 18

It refers to the ability of a material to withstand pulling or stretching forces. (tension)

Question 19

What is strength in the context of materials?

Answer 19

It refers to the ability of a material withstand applied force.

Question 20

How would you define ductility?

Answer 20

It refers to how much a material can stretch or deform under loading. A very ductile material can be stretched to great length before it snaps.

Question 21

What is the definition of density?

Answer 21

Mass of material per unit volume. High density means particles are more densely packed, while low density means particles are more loosely packed.

Question 22

Can there be a perfect material?

Answer 22

No, there are limitations. Properties can be tailored by combining materials, such as alloys and composites.

Question 23

Define ceramics and list their characteristics and properties.

Answer 23

Compounds between metallic and non-metallic elements, hard, brittle, poor tensile strength, high compressive stength, electrical insulators, poor thermal conduction, heat and corrosion resistant.

Question 24

What are the characteristics and properties of polymers?

Answer 24

Non-conductors, low melting point, poor fatigue strength, average toughness, poor tensile and compressive strength.