Materials 1

Question 1

How to derive engineering vs true stress relationship

Answer 1

Constant Volume assumption

V = A * L and σ = P/A

Question 2

How to derive engineering vs true strain relationship

Answer 2

Integrate ΔL/L

Question 3

What does %RDA stand for?

Answer 3

Percentage Reduction in Area

Question 4

Poisson’s Ratio for constant volume

Answer 4

v = 0.5

Question 5

Units of P in hardness tests

Answer 5

kg

Question 6

Stress Amplitude

Answer 6

Half the range

Question 7

Stress Ratio

Answer 7

σ(min) / σ(max)

Question 8

Sensitivity to creep

Answer 8

Operating temp / Melting temp

Question 9

Bonds in Semiconductors

Answer 9

Covalent

Question 10

Bonds in Polymers

Answer 10

Covalent and Secondary

Question 11

Bonds in Metals

Answer 11

Metallic

Question 12

Bonds in Ceramics

Answer 12

Ionic and Covalent

Question 13

Young’s Modulus equation based on atomic structure

Answer 13

E = (2q^2) / (π* ε* r^4)

Question 14

1 Mole

Answer 14

6.02 x10^23

Question 15

Selection metric for Maximum Elastic Energy Storage

Answer 15

M = UTS^2 / E

Question 16

Ductile failure shape

Answer 16

Cup and Cone

Question 17

Ductile failure energy absorbtion

Answer 17

High energy absorbtion

Question 18

Brittle failure shape

Answer 18

Flat

Question 19

Brittle failure energy absorbtion

Answer 19

Low energy absorbtion

Question 20

Stages of creep (ε/t graph)

Answer 20

Initial elastic strain (linear, steep), primary creep (concave), steady-state creep (linear), tertiary creep (convex, accelerating), rupture

Question 21

Why is creep temperature dependent?

Answer 21

Creep is due to the diffusion of atoms

Question 22

Stress amplitude σa for first fatigue test

Answer 22

2/3 * UTS

Question 23

Typical fatigue testing frequencies

Answer 23

5-10 Hz

Question 24

Electrons in outer shell of metals

Answer 24

Nearly Empty

Question 25

Electrons in outer shell of non-metals

Answer 25

Nearly Full

Question 26

Non-directional Bonds

Answer 26

Ionic, Metallic

Question 27

Directional Bonds

Answer 27

Covalent

Question 28

Signs for bond potential energy

Answer 28

Attraction -ive
Repulsion +ive

Question 29

Signs for bond forces

Answer 29

Attractive +ive
Repulsive -ive

Question 30

Define Crystal

Answer 30

Homogenous solid. Atoms/molecules arranged in a regular repeating pattern.

Question 31

Material with Simple Cubic Structure

Answer 31

Polonium

Question 32

Materials with Hexagonal Close Packed (HCP) structure

Answer 32

Magnesium, Titanium, Beryllium

Question 33

Materials with Face Centred Cubic (FCC) structure

Answer 33

Aluminium, Copper, Lead, (Iron between 910-1400 ℃)

Question 34

Materials with Body Centred Cubic (BCC) structure

Answer 34

Chromium, Tungsten, Iron (Below 910 and above 1400 ℃)

Question 35

HCP Lattice Slip Systems

Answer 35

1x3 = 3

Question 36

FCC Lattice Slip Systems

Answer 36

3x4 = 12

Question 37

BCC Lattice Slip Systems

Answer 37

2x6 = 12

Question 38

Critically resolved shear stress τ(crss)

Answer 38

σ * (cos(Φ) * cos(λ))max

Question 39

Minimum stress to cause yielding in a single crystal

Answer 39

σ = 2τ(crss)

Question 40

α - Fe is called…

Answer 40

Ferrite

Question 41

Ferrite Structure

Answer 41

BCC

Question 42

γ - Fe is called…

Answer 42

Austenite

Question 43

Austenite Structure

Answer 43

FCC

Question 44

δ - Fe Structure

Answer 44

BCC (from 1400 to melting temp)

Question 45

Fe3C is called…

Answer 45

Cementite

Question 46

Cementite Carbon Content

Answer 46

6.7% by weight

Question 47

“Eutectoid” carbon content for steel

Answer 47

0.8% C

Question 48

Eutectoid Structure (α + Fe3C) is called…

Answer 48

Pearlite

Question 49

Eutectoid α Phase Carbon Content

Answer 49

0.022% C

Question 50

Creep temp for metals

Answer 50

0.3 Tm

Question 51

Creep temp for ceramics

Answer 51

0.4 Tm

Question 52

How to increase Tg

Answer 52

Increase Chain Stiffness
Increase Bond Strength
Increase Molecular Weight