6.0- General

Question 1

Give the definition for Hardness.

Answer 1

Resist penetration, wear or cutting action.

Question 2

Give the definition for Strength.

Answer 2

Resist stress without breaking.

Question 3

Give the definition for Elasticity.

Answer 3

Return to original size and shape after deformation.

Question 4

Give the definition for Plasticity.

Answer 4

Property that allows it to be reshaped.

Question 5

Give the definition for Ductility.

Answer 5

Drawn into thinner sections without breaking.

Question 6

Give the definition for Malleability.

Answer 6

Stretched or shaped without breaking.

Question 7

Give the definition for Toughness.

Answer 7

Deformed without breaking.

Question 8

Give the definition for Brittleness.

Answer 8

To deform or break when stress and force is applied.

Question 9

What is stress defined as?

Answer 9

Force per unit area.

Question 10

What are the SI units for stress?

Answer 10

N/M² or Pascals.

Question 11

What is the Imperial measure for stress?

Answer 11

psi

Question 12

Give the definition for Tensile stress.

Answer 12

To stretch.

Question 13

Give the definition for Compressive stress.

Answer 13

To squish.

Question 14

Give the definition for Shear stress.

Answer 14

To break.

Question 15

What are the Combined Stresses. (2 combinations)

Answer 15

1) Tensile+ shearing

2) Compressive+ shearing.

Question 16

What is Simple stress?

Answer 16

Just one of the stresses acting.

Question 17

What is Unit strain?

Answer 17

Deformation of shape due to application of load divided by original dimension.

Question 18

What is Poissons ratio?

Answer 18

Ratio of lateral to longitudinal strain to a material when subject to uniform longitudinal stress. E.g. when you stretch it how much thinner does it become.

Question 19

What is the poisson ratio values for steel?

Answer 19

0.30

Question 20

What is the poisson ratio values for wrought iron?

Answer 20

0.28

Question 21

What is the poisson ratio values for cast iron?

Answer 21

0.27

Question 22

What is the poisson ratio values for brass?

Answer 22

0.34

Question 23

Give the definition for metallic.

Answer 23

Contains metal or metal alloys.

Question 24

Give the definition for ferrous.

Answer 24

Contains iron.

Question 25

Give the definition for elastic limit.

Answer 25

Item can return to its original shape after acting force is removed.

Question 26

What is the elastic limit of steel also known as?

Answer 26

The proportional limit.

Question 27

Give the definition for yield strength?

Answer 27

Maximum stress that can be applied without permanent deformation.

Question 28

Give the definition for ultimate tensile strength?

Answer 28

Maximum stress that can be applied without breaking.

Question 29

What is the modulus of elasticity?

Answer 29

Ratio of stress to strain within the proportional limit of material in tension or compression.

Question 30

In a phase diagram what are the axis always labelled as?

Answer 30

y- temp | x- percentage of alloy.

Question 31

For airframes what density of metal is normally used?

Answer 31

Below 5 Kg/dm³.

Question 32

What are the three most important metals in aircraft structure?

Answer 32

1) Aluminium and alloys 2) Titanium and alloys 3) Magnesium and alloys

Question 33

What is the density of aluminium?

Answer 33

2.7Kg/dm³.

Question 34

What is the density of titanium?

Answer 34

4.5Kg/dm³.

Question 35

What is the density of magnesium?

Answer 35

1.74Kg/dm³.

Question 36

Where can metal densities between 7.85 and 9.5 Kg/dm³ be used?

Answer 36

Aircraft structure where high weights or higher strengths are needed.

Question 37

What is the definition of a crystal?

Answer 37

A rigid body where all particles form in a repeating pattern.

Question 38

How many atoms does Body centred cubic have (BCC)?

Answer 38

9

Question 39

How many atoms does a face centred cubic have (FCC)?

Answer 39

14

Question 40

What metals are examples of FCC? (6 examples)

Answer 40

Aluminium, copper, gold, nickel, silver and iron.

Question 41

What metal is a bcc below 910°c and fcc above 910°c?

Answer 41

Iron.

Question 42

How many atoms in hexagonal close packed (HCP)?

Answer 42

17.

Question 43

What metals are HCP? (4 examples)

Answer 43

Cobalt, magnesium, titanium, zinc

Question 44

What are the different characteristics considered in material selection?

Answer 44

Quality, cost, maintenance, repair