Rolls Royce

• WJEC UNIT 3

  Dr Abraham Wiri
• Mechanical systems


  • gears
  • bearings
  • linkages etc.
• Additional useful information
• Slide 14
• Slide 3
• Slide 20
• Slide 25
• Slide 34
• Slide 37
• Slide 45
• Slide 53
• Slide 56
• Slide 63
• Slide 70
• Slide 72
• Architectural structures


  • Buildings are often designed using a frame or shell structure
  • Many structures make use of triangulation to give the form strength
• Shell structure


  One surface, and gains strength from its form
• Shell structures


  • Sydney opera house
  • coke cans
• Triangulation


  • Use of triangular shapes to give stability to structures
  • Triangles are particularly good at resisting force applied to compress them

  
• Frame structure


  • Made up of multiple parts joined together
  • Most large buildings are built this way using structural steel joists

  
• Ladder chassis


  • Simplest form of chassis
  • Mechanical running gear is mounted onto a chassis system which is separate from the vehicle's body
  • The overall weight of the vehicle is higher that the other 2 methods
• Space frame chassis


  • Complex frame of welded metal bars to provide the structure
  • The running gear is mounted within this frame, and body panels secured to the outside
  • Very strong and lightweight
  • Used in motorcycle, off road and some sports car applications

  
• Monocoque chassis


  • Body and chassis are one unit made of various panels secured together
  • Reduces additional unnecessary weight while maintaining body rigidity and strength
  • Assembly can be largely automated

  
• Compression


  An object is put under pressure making it smaller
• Tension


  A stretching force is being applied which tries to make the object longer
• Bending


  A force is applied to the middle of an object to distort it
• Torsion


  A twisting force applied to an object
• Shear


  Two forces are applied in opposite directions across an object
• Few areas have developed as quickly as electronics
• Moore's Law


  The number of transistors on a chip doubles every two years while the costs are halved
• Transistors


  • Electronic switches
  • Switched via a small electric current
  • Can handle a large current between Collector and Emitter
  • Only require a small current to the Base to switch
  • Often used to amplify current
  • Output current is proportional to the input current
• Darlington Pair


  Two transistors arranged so the first switching on applies a larger current the Base of the second transistor, allowing more current to pass from it's Collector to Emitter
• Battery timeline


  • Lead Acid batteries
  • NiCD – Nickel-cadmium
  • NiMH – Nickel-metal hydride
  • Lithium ion batteries
• Advantages of the newer batteries

  • Lighter
  • More capacity
  • More power
  • More shape options
  • Minimal 'memory'
• Screen timeline


  • CRT – Cathode ray tube
  • LCD display – Liquid crystal distal
  • Touch screen
  • 4K display
  • Flexible displays? (Currently under development)
• Advantages of the newer screens

  • Smaller
  • Require less energy
  • Higher quality
  • Thinner
  • Lower cost
• Electronic components


  • LED
  • Resistor
  • Push to make (PTM) switch
  • Capacitor
  • Transistor
  • Variable resistor
• PCB Engraving


  The material between tracks is physically removed with a sharp engraving tool on a CNC mill
• PCB Etching


  The material between tracks is removed in an acid bath. The tracks are protected with a film
• Pick and place


  • Modern circuit boards are populated automatically
  • Surface Mount Components are rested on top of pre-soldered tabs
  • The whole board is heated to melt the solder and make the connection