Forces on materials
- Tension: a pulling force that stretches a material, such as a rope in a tug of war.
- Compression: a pushing force that squashes a material, such as the legs of a chair.
- Bending: a force that makes a material curve, such as a shelf with books on it.
- Torsion: a twisting force, such as turning a screwdriver.
- Shear: forces acting in opposite directions that slide one part of a material past another, such as scissors cutting paper.
Reinforcing and stiffening materials
- Paper and board: folding, laminating (layering) and adding ribs or corrugations make card stronger, such as corrugated card.
- Timber: laminating thin layers (as in plywood) and adding braces or struts.
- Metals: folding, bending, adding ribs, or making tubes and I-beams, which are stiff for their weight.
- Polymers: ribs and webbing in moulded products, such as the ribs inside a plastic case.
- Textiles: interfacing (an extra fabric layer) stiffens collars and cuffs; quilting and lamination add strength.
Why it matters
- Designers must know which forces a product will face so they can choose a strong enough material and shape.
- Changing the shape (such as a tube or corrugation) can make a product stronger without using more material.
Key terms
- Tension
- A pulling force that stretches a material.
- Compression
- A pushing force that squashes a material.
- Torsion
- A twisting force.
- Shear
- Forces that slide one part of a material past another.
- Bending
- A force that makes a material curve.
- Laminating
- Bonding layers of material together for strength.
- Interfacing
- An extra layer of fabric used to stiffen parts of a garment.