Engineering Accelerated AT 1

• Key Words for Nature and Range of work of engineers

  Researching, developing, designing, constructing, testing, evaluating and modifying
• Ancient Era


  The wheel, wood and stone
• Middle ages


  More arches and taller buildings
• Industrial Revolution


  Electrical engineering, metal and mass production
• Renaissance


  Technical drawings started and domes became more popular
• Modern Era


  Lots of metal and the use of tensile and compressive forces, prestressing etc
• Mass


  Kg
• Force


  Newtons (N)
• Scalar Quantities


  Non directional, only need magnitude
• Vector Quantities


  Point of application, amplitude, sense (the arrow), and direction
• Properties of Materials


  Ductility, Malleability, Hardness, Elasticity, Strength, Toughness
• Strength


  The ability of a material to withstand a load or force without failure.
• Toughness


  The ability of a material to withstand an impact force and deform plastically before fracturing
• Metallic bonds


  a bond formed by the attraction between positively charged metal ions and the electrons around them (the electron cloud)
• BCC


  Body centred cubic structure, Cube of atoms one in the center, less dense hence more interlocking and therefore less ductility but increased strength. Iron at regular temperature, volume of 2
• FCC


  Face centred cubic, Structure which has a cube of atoms with an atom in the centre of each face. More dense hence less interlocking and less strength. Iron at Red Heat. Volume is 4
• CPH


  Close packed Hexagonal structure, orientation of atoms means less slip planes, hexagonal prism with one in the centre of the top and bottom hexagons and 3 in a triangle in the very centre of the stucture.
• Ferrous metals


  >50% iron
• Non Ferrous metals


  <50% iron
• Hot rolling


  Used to reduce a Ingot or billet Down to required shape, produce equiaxed, unstressed and refined grains (small round and removed work hardening)
• Cold rolling


  Better finish than hot rolling, grain flow makes it stronger, work hardening.
• Extrusion


  Metal is forced, under pressure to flow through a die, this can be done hot or cold, but the material needs to be ductile. Increases strength, toughness and hardness.
• Drawing


  Reduces the cross sectional area of rods by pulling them through a tungsten carbide die.
• Deep Drawing


  Forces a metal into a die like a stamp, can make coins all the way to kitchen sinks.
• Powder processing


  Mixing then Compacting metal powders into a die and forming a component, then sintering (Around red heat) the part under the melting point to achieve bonding.
• Thermosoftening


  A polymer that becomes soft when heated and can be remoulded into new shapes.
• Thermo Setting


  A polymer that has been hardened due to heat
• Common Ceramics


  Glass, Pottery, Bricks, Heat Shields, Hardened Cement
• Properties of Ceramics


  Good insulators, Hard and Brittle, High compressive and low tensile strength, chemically inert.
• Composites

  Bonded materials for better properties. e.g. Fibres and matrix
• Coplanar Forces


  Forces acting in the same plane e.g. three people pushing a car
• Concurrent Forces


  All forces meet at a common point
• Co-Linear Forces


  All forces act along the same line e.g. tug of war
• Gravity


  10 m/s2 This is to ensure a factory of safety and to make it easier :)
• Steel


  All ferrous alloys containing <2% Carbon
• Alloy Steels


  Steels with a significant amount of other elements e.g. Chromium in Stainless and Molybdenum in Aircraft steels
• Cast irons


  2% - 4% Carbon alloys of iron which are cast to a shape in a mould while liquid.
• Ferrite


  BCC iron with up to 0.04% Carbon, soft and ductile
• Austenite


  Up to 2% carbon, FCC, and is formed when Iron reaches the austenitic zone or recrystallisation temperature, for iron 723 degrees.
• Cementite


  Fe3C, formed when Austenite cools, 2% Carbon, Extremely Hard and brittle