MATERIALS A substance that has been completed or transformed by humans and is then used to make or be a part of a technical object. - Mechanical constraints (reaction to external forces) - Effects on materials produced by constraints of increasing intensity - Mechanical properties - Different categories of materials (wood, metals & alloys, plastics)

Mechanical Constraints describe the stress produced within a material when it is subjected to external forces (rigours of the environment such as temperature, humidity, and pressure). FIVE PRINCIPAL MECHANICAL CONSTRAINTS: 1 – COMPRESSION 2 – TENSION 3 – TORSION 4 – BENDING 5 - SHEARING

COMPRESSION Force that crushes materials BENDING Force that bends material TORSION Force that twists material TENSION Force that stretches material SHEARING Force that cuts or tears material

EFFECTS ON MATERIALS PRODUCED BY CONSTRAINTS OF INCREASING INTESITY 1 – ELASTIC DEFORMATION: this results in the temporary deformation of the material. When the constraint is removed, the material regains its shape. 2 – PLASTIC DEFORMATION: even when the constraint is removed, the material remains deformed. 3 – FRACTURE: the material ruptures after being subjected to the constraint.

FRACTURE: chalk is ruptured PLASTIC: metal of car remains deformed after it is separated from the pole. ELASTIC: boxer hits the bag and it returns back to its shape after the hit.

* A MECHANICAL PROPERTY determines how a material will react when it is subjected to one or more mechanical constraints. 1- HARDNESS 2 – ELASTICITY 3 – RESILIENCE 4 – DUCTILITY 5 – MALLEABILITY 6 – TENSILE STRENGTH

* Resists penetration (reacts to locally applied pressure force by elastic deformation). * Marble is hard; it is difficult to make a hole in it.

* Regains its initial shape after being subjected to a force (reacts to force by elastic deformation) * Coils are springy

* Resists physical impacts (reacts to temporary force by elastic deformation). * The steal frame adds resilience to this construction

* Stretches without breaking (reacts to tension force by plastic deformation) * Copper can be stretched to make wires

* Flattens or bends without breaking (reacts to bending or compression by plastic deformation). * Metals are malleable enough to be made into sheets

* Resists tension without becoming permanently deformed (reacts to tension force by elastic deformation) * The crane’s cable must have enough tensile strength to resist the tension placed on it by wrecking ball

WOOD METAL PLASTIC STONE CERAMIC TEXTILE GLASS SYNTHETIC MATERIALS

* Wood is a material that comes from cutting and processing trees. * HARDWOOD comes from deciduous trees and is primarily used in the manufacturing of furniture and flooring. * SOFTWOOD comes from coniferous trees and is primarily used in residential construction and paper manufacture. FACTORS THAT EFFECT THE MECHANICAL PROPERTIES OF WOOD - species of tree - growth rate of tree - moisture content of tree - injuries sustained by tree

MECHANICAL PROPERTYVARIATION AMONG SPECIES -HARDNESS Hardwood, healthier, moisture, and cold increase hardness -ELASTICITY Good. Can suffer impacts without permanent deforming -RESILIENCE Adequate moisture creates better resilience -DUCTILITY Not much ductility. Can’t really be stretched -MALLEABILITY Heat increases malleability. Can be bent a certain amount - TENSILE STRENGTH Excellent. Rot decreases strength of wood FOUR REASONS WHY WOOD IS SUCH A COMMONLY USED MATERIAL 1 – IT IS EASILY WORKED 2 – IT IS EASY TO ASSEMBLE 3 – IT IS A GOOD THERMAL INSULATOR 4 – IT DOES NOT CONDUCT ELECTRICITY

* HARDWOOD: (leafy, summer trees) MAPLE – furniture, flooring, trim YELLOW BIRCH – furniture, flooring, toys, kitchen cabinets OAK – furniture, flooring, kitchen cabinets, support columns * SOFTWOOD: (needle, evergreens) SPRUCE – papermaking, construction, musical instruments PINE – furniture, doors, papermaking, construction CEDAR – outdoor decks, closets, furniture, construction

* MODIFIED WOOD is treated wood or material made with wood mixed with other substances. * ADVANTAGES: - Stable mechanical properties - More resistance to inclement weather - Used to manufacture larger materials - Can be made by smaller trees - Can be made with wood chips and wood waste (such as saw dust)

MODIFIED WOOD TYPE MANUFACTURING PROCESSAPPLICATIONS - TREATED WOODHeated. Dipped in copper based chemical. Objects or structures in which wood is exposed to rain or snow. - LAMINATED WOODGluing small pieces of wood together. Snowshoes Building structures Tables -PLYWOODGluing large sheets of wood so the fibres are at a right angle to those below them. Work tables Construction (floors) - PARTICLE BOARDMade with wood chips and wood waste. Particles are bonded with various products Construction Trunks Toys - FIBREBOARDSeparated wood fibres into smaller bits then bonded with various products. Insulation Furniture Floating floors

* METAL is a material extracted from an ore. Metals are usually shiny and are good conductors of electricity and heat. * ALLOY is the result of a mixing of metal with one or more metallic or non-metallic substances. * FERROUS ALLOY is an alloy whose main constituent is iron. * A NON-FERROUS ALLOY is an alloy whose main constituent is a metal other than iron.

METALCHARACTERISTICSUSEFUL PROPERTIESAPPLICATIONS -IRONSilvery Rust prone Soft Most common Ductility Malleability Automobiles Buildings Utensils, Nails Cables -COPPERRed-brown Best conductor Ductility Malleability Conductivity Electrical wires Musical instruments Pennies -ALUMINUMWhite, soft Abundant (2 nd ) Malleability Light weight Corrosion resistance Conductivity Pleasure boats Foil Cans Electrical products -ZINCWhite-bluishDuctility Malleability Corrosion resistance Electrical wires Gutters Surface coating -MAGNESIUMSilvery-white Burns easily Light weight Flammable Fireworks/Bengal lights Cans -NICKELGreyHardness Malleability Corrosion resistance Heating elements Coins -CHROMEWhite-bluishExtreme hardness Corrosion resistance Surface coating - TINSilvery -whiteDuctility Malleability Lowest melting point Wielding Utensils

ALLOYCOMPOSITION AND DESCRIPTION USEFUL PROPERTIES APPLICATIONS -STEELMix of iron/carbon <1.5% Nickel, chrome, and zinc are added Hardness Resilience Malleability Tensile strength Construction tools Building structures Automobiles - CAST-IRONMix of iron/carbon >2%HardnessCookware Wood stoves Engine blocks -BRASSMix of copper and zincDuctility Malleability Corrosion resistance Decoration Automobiles Electronic parts -BRONZEMix of copper and tinHardness Malleability High density Corrosion and wear resistance Art objects Olympic medals Boat propellers -ALUMINUM ALLOY Small amount of many substances (copper, manganese, silicon, zinc, etc) Malleability Low density Corrosion resistance Light weight Car parts Airplane parts Electronic parts

* 1970s invention. From petroleum or natural gas. PLASTIC is manufactured material made of polymers. * Can be easily moulded. Once moulded, they keep their shape. * Two categories: Thermosetting plastics and Thermoplastics * THERMOSETTING PLASTICS: plastics that harden permanently under the effect of an energy source such as heat, irradiation or a chemical reaction. This process gives the plastic great rigidity. * THERMOPLASTICS: plastics that soften when heated and harden when cooled. Can be reshaped when softened, maintaining their new shape when cooled. 75% of all plastics * Various colors, durable, do not rust, lightweight, and inexpensive.

THERMOPLASTICRECYCLING CODE PROPERTIESAPPLICATIONS - POLYTHYLENE TEREPHTALATE 1 - PETEImpact, gas, heat, and moisture resistant Bottles Containers (jam) Oven-proof -POLYTHYLENE2 – HDPE 4 – LDPE Flexible, Easily cut, moulded Moisture resistant Squeeze bottles Garbage, grocery bags Plastic wrap Beach balls - POLYVINYL CHLORIDE3 – VHard Resistant to grease, oil, and chemicals Medicine tubes Patio furniture CD cases, Piping, window frames -POLYPROPYLENE5 – PPImpact, heat, oil, and water resistant Containers (yogurt) Water bottles Car bumpers Geotextiles -POLYSTYRENE6 - PSInsulation Foam or rigid plastic forms Slab insulation Plastic dinner wear Food packaging -POLYAMIDENOT RECYCLABLEElastic Absorbs water Textiles Electrical components - POLYMETHYL METHACRYLATE (ACRYLIC) NOT RECYCLABLEVery rigid Various colors Transparent bowls Signs Dental prostheses