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 |
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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 |
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Polymers
Polymers |
A plastic |
Thermoplastic Polymer |
Can be reshaped when heated |
Thermosetting Polymer |
Cannot be reshaped when heated |
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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 |
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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 |
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