• HDP and HIP are both High Density, or High Impact, Polystyrene.
  • Wood from deciduous trees is harvested during winter when they cease growing and the resin hardens:
    • This makes the wood stronger.
  • Pine bows very easily.
  • Galvanised steel has a high resistance to corrosion.

What Influences Choice of Materials and Components:

  • Service:
    • What does the product need to be able to do.
  • Properties:
    • What are the characteristics the material will need to have? Does it have to be strong? Etc.
  • Environment:
    • What sort of environment will the product be used in.
  • Aesthetics:
    • What will the product look like? Is it necessary for it to have a particular look, colour or feel.
  • Availability.
  • Cost.
  • Processing capabilities.

Properties of Materials:

  • Mechanical properties:
    • Strength – Ability of a material to withstand an applied force.
      • Compressive strength – The ability to withstand pushing forces.
      • Tensile strength – The ability to withstand stretching forces.
    • Hardness – Measure of how easily a material is scratched or indented:
      • Very hard materials are often in possession of low impact resistances meaning that they are very brittle.
    • Toughness – How well a material absorbs impact.
    • Stiffness – The ability to resist bending.
    • Ductility – It is the ease with which a solid material deforms under tensile stress.
    • Malleability – Is the ease with which a material may be deformed under compressive stress.
  • Physical properties:
    • Thermal conductivity.
    • Resistance to corrosion – How slowly a material corrodes.
      • Including how slowly a material oxidizes.
    • Electrical conductivity.
    • Optical properties – How easily light passes through a material.
    • Appearance – Considerations such as aesthetics, colour, brightness and texture.
    • Joining properties – How easily a material is joined to itself or to other materials.
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