Forces

• Types of forces/stresses

  • Tension
  • Compression
  • Bending
  • Torsion
  • Shear
• Tension


  • Forces pulling in opposite directions.
  • Concrete can have steel bars inserted to reinforce
• Compression


  • Forces that are trying to crush or shorten.
  • Composite materials can have a honeycomb structure sandwiched in the middle to resist
• Bending

  • Flexing force.
  • Steel beams have a I profile to resist bending
• Torsion

  • Twisting force.
  • The diagonals on a tower crane help the structure against torsion
• Shear


  • A strain produced when an object is subjected to opposing forces.
  • Bolts are hardened and have unthreaded shanks to stop shearing
• Lamination


  1. Layering of thin materials

  2. Depending on the direction of lamination it can make boards stiffer or actually more flexible
• Lamination examples


  • Plywood: Laminations at 90 degrees to each other-Rigid
  • Flexi-ply: Laminations all the same direction-Bendy
• Bending/Folding

  1. Folding a 90 degree edge on sheet metal

  2. Makes the panel more rigid
• Bending/Folding examples


  • Body panels on cars
• Webbing

  Extremely strong and durable fabric woven together
• Fabric interfacing


  A strengthening material added to the unseen face of a fabric to add strength/shape
• Seasoning

  Removes the moisture content so that the timber will not shrink, warp and twist
• Annealing


  Softens the copper to make it more malleable
• Addition of stabilisers


  Stops plastic become brittle with exposure to the sun