Materials in Mechanical Design

Question 1

The food of design

Answer 1

Materials

Question 2

It refers to the one that performs well, is good value for money and gives pleasure to the user.

Answer 2

Successful product

Question 3

Six broad classes of Engineering materials

Answer 3

Metals, Polymers, Elastomers, Ceramics, Glasses, Composites

Question 4

This class has relatively high moduli.

Answer 4

Metals

Question 5

Metals can be made strong through what method?

Answer 5

By alloying, by mechanical and heat treatment

Question 6

A high-strength alloy with ductilities as low as 2%.

Answer 6

Spring steel

Question 7

Metals are prey to fatigue partly due to what?

Answer 7

Their ductility

Question 8

Of all classes of material, they are the least resistant to corrosion.

Answer 8

Metals

Question 9

A class of engineering material that has high moduli but are brittle.

Answer 9

Ceramics and Glasses

Question 10

They have no ductility and have low tolerance for stress concentrations or high contact stresses.

Answer 10

Ceramics

Question 11

They are stiff, hard and abrasion-resistant. They retain their strength to high temperatures and they resist corrosion well.

Answer 11

Ceramics

Question 12

They have low moduli, roughly 50 times less than those of metals, but can be as strong as metals.

Answer 12

Polymers and Elastomers

Question 13

What is the property of polymer at 20 degrees celcius?

Answer 13

Tough and flexible

Question 14

What is the property of polymer at 4 degrees celcius of a household refrigerator?

Answer 14

Brittle

Question 15

What is the property of polymer at 100 degrees celcius of boiling water?

Answer 15

Creeps rapidly

Question 16

What temperature do the polymers no longer have useful strength?

Answer 16

Above 200 degrees celcius

Question 17

TRUE OR FALSE. When combinations of properties, such as strength per-unit-weight, are important, polymers are as good as glasses.

Answer 17

FALSE [ Glasses - Metals ]

Question 18

They are easy to shape, corrosion resistant, have low coefficients of friction and have large elastic deflections.

Answer 18

Polymers

Question 19

This class combines the attractive properties of the other classes while avoiding some of their drawbacks.

Answer 19

Composites

Question 20

They are light, stiff and strong, and can be tough.

Answer 20

Composites

Question 21

Composites cannot be used above 250 degrees celcius because?

Answer 21

The polymer matrix softens

Question 22

At what temperature do composites have outstanding performance?

Answer 22

Room temperature

Question 23

Only when do the designers use composites?

Answer 23

When the added performance justifies the added cost

Question 24

It defines the behavior of materials under the action of external forces.

Answer 24

Mechanical properties of materials

Question 25

These external forces are also called as?

Answer 25

Loads

Question 26

How do we determine the mechanical properties of metals ?

Answer 26

By the range of usefulness of the metal and establish the service that is expected.

Question 27

What are the 7 most common properties?

Answer 27

Strength, ductility, hardness, brittleness, toughness, stiffness, Impact resistance

Question 28

It is the ability to undergo some permanent deformation without rupture (brittle).

Answer 28

Plasticity

Question 29

It is the ability of a material to resume its normal shape after being stretched or compressed.

Answer 29

Elasticity

Question 30

It is a property of materials which enables it to withstand permanent deformation.

Answer 30

Brittleness

Question 31

It is a property of a material that enables it to withstand shock or impact.

Answer 31

Toughness

Question 32

It is a property of a material which permits it to be hammered or rolled into sheets.

Answer 32

Malleability

Question 33

It is a property of a solid body by virtue which they resist from being broken into a fragment.

Answer 33

Cohesion

Question 34

It is a property that enables metals to resist deformation load.

Answer 34

Strength

Question 35

It is the ability of a material to resist scratching, abrasion, cutting or penetration.

Answer 35

Hardness

Question 36

It is the capacity of a material to withstand destruction under action of external loads

Answer 36

Strength

Question 37

TRUE OR FALSE. The stronger the materials, the lesser the load it can withstand.

Answer 37

FALSE [ Lesser - Greater ]

Question 38

Good examples of elastic materials

Answer 38

Heat-treated springs and rubber

Question 39

It is also called dynamic hardness.

Answer 39

Rebound Hardness

Question 40

It is the ability of materials to oppose the scratches to the outer surface layer due to external force.

Answer 40

Scratch Hardness

Question 41

It is the ability of materials to oppose the dent due to punching or external hard and sharp objects.

Answer 41

Indentation Hardness

Question 42

It is the is the resistance of a material to elastic deformation or deflection.

Answer 42

Stiffness

Question 43

It is the ability of a metal to resist suddenly applied loads.

Answer 43

Impact strength

Question 44

It is a property of a material which enables it to be drawn out into a thin wire.

Answer 44

Ductility

Question 45

It is the long effect of repeated straining action which causes the strain or break of the material.

Answer 45

Fatigue

Question 46

It is used to describe the fatigue of material under repeatedly applied forces.

Answer 46

Fatigue

Question 47

Examples of malleable materials

Answer 47

Aluminum, copper, tin, lead

Question 48

It has high compressive strength but low in tensile strength.

Answer 48

Brittle metals

Question 49

Examples of brittle metals

Answer 49

Cast iron, glass

Question 50

It is a slow and progressive deformation of a material with time at a constant force.

Answer 50

Creep

Question 51

The simplest type of creep deformation

Answer 51

Viscous flow

Question 52

The force for a specified rate of strain at constant temperature.

Answer 52

Creep strength

Question 53

They are hard, non-adhesive, cold and smooth, they are very often shiny and strong.

Answer 53

Metals

Question 54

A process by which metals react with oxygen in water and air

Answer 54

Oxidation or rusting

Question 55

A reddish- or yellowish-brown flaky coating of iron oxide that is formed on iron or steel, especially in the presence of moisture.

Answer 55

Rust

Question 56

Examples of metals that are toxic

Answer 56

Lead or mercury

Question 57

Metals can be divided into two main groups

Answer 57

Ferrous metals and non-ferrous metals

Question 58

It is considered to be of little use as an engineering material because it is too soft and ductile.

Answer 58

Pure iron

Question 59

Some iron cools and changes from a liquid to a solid become misaligned, creating areas of weaknesses called?

Answer 59

Dislocations

Question 60

It is a mixture of two or more chemical elements and the primary element is a metal.

Answer 60

Alloy

Question 61

By adding carbon to the iron however, we can produce a range of alloys with quite different properties called?

Answer 61

Carbon steels

Question 62

It has a carbon content between 0.1% and 0.3%. Less ductile but harder and tougher than iron, grey color, corrodes easily.

Answer 62

Mild Steel

Question 63

It has a carbon content between 0.3% and 0.7% carbon. It is harder and less ductile than mild steel, tough and have a high tensile strength.

Answer 63

Medium carbon steel

Question 64

It has a carbon content between 0.7% and 1.3% carbon. It is very hard and brittle material.

Answer 64

High carbon steel `

Question 65

An element that prevents rusting with an oxide film.

Answer 65

Chromium

Question 66

It is an alloy of iron (94%), carbon (3%) silicon (2%) and some traces of magnesium, sulphur and phosphorous.

Answer 66

Grey Cast Iron

Question 67

A chemical element that makes the alloy magnetic and improves elasticity.

Answer 67

Silicon

Question 68

A chemical element that improves strength and prevents corrosion.

Answer 68

Nickel

Question 69

A chemical element that makes the alloy harder and heat-resistant. It's used to make stainless steel.

Answer 69

Manganese

Question 70

A chemical element that makes the alloy harder and tougher and more rustproof.

Answer 70

Chromium

Question 71

A chemical element that makes the steel harder, more heat-resistant and prevents corrosion.

Answer 71

Tungsten

Question 72

They are metals that don't contain iron.

Answer 72

Non-ferrous metals

Question 73

It's the most abundant metal in the earth's crust and after steel, is the most widely used of all the metals.

Answer 73

Aluminum

Question 74

It's a pure metal that is the world's third most important metal, in terms of volume of consumption.

Answer 74

Copper

Question 75

It covers a wide range of copper-zinc alloys.

Answer 75

Brass

Question 76

It has very good anticorrosive properties and it's resistant to wear.

Answer 76

Brass

Question 77

It's shiny and silvery white. It reacts very strongly with oxygen.

Answer 77

Magnesium

Question 78

It doesn't oxidize at room temperatures and is very soft.

Answer 78

Tin

Question 79

It is toxic when its fumes are inhaled

Answer 79

Lead

Question 80

It's an alloy of copper and tin.

Answer 80

Bronze

Question 81

It is a bluish grey shiny metal.

Answer 81

Zinc

Question 82

It contains Iron as a major component

Answer 82

Ferrous alloys

Question 83

It does not contain Iron as a major component.

Answer 83

Non-ferrous alloys

Question 84

The major categories of manufacturing processes

Answer 84

– Metal Casting, – Bulk/Metal Deformation, – Sheet Metalworking/metal forming, – Machining, – Polymer Processing, – Powder Metallurgy, – Finishing and – Assembly.

Question 85

Other non-value added processes of manufacturing processes

Answer 85

– Inspection, – Testing, and – Quality assurance.

Question 86

A manufacturing process that creates complex shapes from molten metal.

Answer 86

Metal casting

Question 87

It creates intricate wax patterns that are coated with slurry, the wax melted out, then filled with molten metal.

Answer 87

Investment casting

Question 88

It uses permanent molds into which low melt point metals such as zinc are injected under pressure.

Answer 88

Die casting

Question 89

Two types of die casting machines

Answer 89

Hot and cold chamber

Question 90

It is used to transform bulk materials in the form of billets, blooms, and slabs as they come from a mill into other shapes such as pipe or bars.

Answer 90

Metal deformation

Question 91

It is a common method for making plastic bottles.

Answer 91

Blow molding

Question 92

This is a common method of making tires.

Answer 92

Polymer Processing

Question 93

It is another compression molding technique in which the heated polymer is injected into the closed mold.

Answer 93

Transfer molding

Question 94

It encompasses many final operations that make a part ready for assembly.

Answer 94

Finishing

Question 95

It is where the different parts that compose a finished product come together.

Answer 95

Assembly