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Engineering Materials Cheat Sheet (DRAFT) by

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Material Properties

Strength
The ability of a material to resist an applied force
Tensile Strength
The maximum pulling force a material can withstand before failure
Yield Strength
The amount of stress at which the material will reach plasticity
Ultimate Tensile Strength (UTS)
The amount of stress at which a material breaks
Compre­ssive Strength
The resistance of a material under a pushing force
Ductility
The amount that a material can be stretched while being deformed
Mallea­bility
The ability of a material to be deformed without breaking
Hardness
The ability of a material to resist wear and abrasion
Toughness
The ability of a material to withstand an impact without breaking
Brittl­eness
The potential for a material to shatter when experi­ences an impact
Stiffness
The ability of a material to resist bending
Elasticity
The ability of a material to return to its original shape when the load upon its removed
Plasticity
When you stretch a material and it doesn't return to its original shape once the force is removed

Calcul­ations

Stress
The force per unit area of a material- N/mm2
Stress Equation
Stress= force/­cross sectional area
Stress Symbol Equation
‎σ= F/A
Strain
The ratio of an amount a material is extended to its original length
Strain Equation
Strain= Change in length­/Or­iginal length
Strain Symbol Equation
ε= Δl/l
Young's Modulus
The measure of how much force is needed to stretch or compress a substance- N/mm2
Young's Equation
Young's Modulus= Stress­/Strain
Young's Symbol Equation
E= σ/ε
Factor of Safety
How mcuh stronger the product is than it needs to be for expected loading
FoS Equation
FoS= Yield Stress­/Load Stress
FoS Symbol Equation
FoS= σy/σL
 

Metals and Alloys

Ferrous Metals
Contains iron
Generally tougher and stronger
They are magnetic
Non-Fe­rrous Metals
Doesn't contain iron
Malleable and ductile
They are not magnetic
Alloys
Made from two or more base metals to improve properties
Ferrous Metals
Cast Iron
3-3.5% Carbon
Cheap, rusts easily, hard, good compre­ssive strength
Anvils, vices
Low Carbon Steel
Less than 0.3% Carbon
Lower strength, tough, cheap
Nails, Car bodies
High Carbon Steel
0.8-1.4% Carbon
Strong and tough
Difficult to form
Saw blades, hammers
Stainless Steel
At least 11.5% Chromium
Strong, hard, expensive
Difficult to machine
Good corrosion resistance
Cutlery
Non-Fe­rrous Metals
Aluminium and its alloys
Light, soft, ductile, malleable
Good conductor of heat and electricity
Corrosion-resistant
Aircraft bodies, foil, saucepans
Copper
Tough, malleable
Good conductor of heat and electricity
Easily Joined
Wires, printed circuits
Brass
65% Copper and 35% Zinc
Casts well, easily joined
Castings, boat fittings
Bronze
90% Copper and 10% TIn
Tough and hardwearing
Bearings, coins, water and steam valves
Lead
Very soft, low m.p, heavy common metal
Roof coverings
Zinc
Poor streng­th-­weight ratio, low m.p
Coating steel
 

Polymers

Polymers
A plastic
Thermo­plastic Polymer
Can be reshaped when heated
Thermo­setting Polymer
Cannot be reshaped when heated
 
Thermo­plastic
ABS
Strong and rigid
Toys
Keyboard
Acrylic
Transp­arent, hard wearing
Plastic Windows
Bath tubs
Nylon
Ductile, durable
Gear wheels
Polyca­rbonate
High Strength
Heat resistant
Safety glasses
DVDs
Polyst­yrene
Tough, Good impact strength
Packaging, Foam cups
 
Thermo­setting
Epoxy
Stiff and brittle
Temperature, Chemical and Electrical resistance
Circuit boards, Electrical insulator
Polyester Resin
Cheap, good strength and stiffness
Suitcases
Melamine Resin
Resistant to some chemicals and stains
Laminate coverings for kitchen worktops
Polyur­ethane
Hard with high strength
Flexible and tough
Low thermal conduc­tivity
Hoses, surface coatings and sealants
Vulcanised Rubber
Elastic, High tensile strength, resistant to abrasion
Tyres, shoe sales, bouncing balls

Compos­ites, Ceramics & Timber

Composites
A type of material made by combining two or more different types of materials
Reinfo­rcement
The particles of fibres within a composite matrix that increases its strength
CRP:
Carbon fibres in an epoxy resin matrix
Extremely high strength, Low density, Expensive
Racing bicycles
Helmets
GRP:
Glass fibres in a polyester resin matrix
High strength, Good chemical resist­ance, Lower cost than CRP
Canoes
Water tanks
Plywood:
Layers of wood bonded at 90° to each other, using adhesive matrix
Smooth surface and good strength, May be covered in veneer
Furniture
Boat building