When studying materials and especially when selecting
materials for a project / design, it is important to understand key
properties. The most important properties are outlined below.
The ability of a material to stand up to forces being
applied without it bending, breaking, shattering or deforming in any
way.
Our technology technician (Ed) demonstrates the ‘strength’ of a
material by performing a hand stand on a strong piece of timber (wood).
It does not bend even under his weight. He has eaten pies and drunk a
large amount of beer for twenty years and yet the strong material does
not bend, flex or deform (change shape) in any way.
ELASTICITY
The ability of a material to absorb force and flex in
different directions, returning to its original position.
Our technology technician demonstrates the ‘elasticity’ of a material by
springing up and down on a piece of steel rod. Do not try this at home
as an accident may result. Ed our technician is an expert at
demonstrating this property as it is his hobby.
PLASTICITY
The ability of a material to be change in shape
permanently.
Our technology technician and his twin brother demonstrate the
‘plasticity’ of a molten aluminium by pouring it into a mould. Once the
aluminium has cooled down, it can be removed from the casting sand. It
has a new shape.
Our technician is often seen scavenging in dust bins after aluminum
drinks cans. He then melts them down to form blocks (ingots) of
aluminium to sell to scrap metal dealers.
DUCTILITY
The ability of a material to change shape (deform)
usually by stretching along its length.
Our technician stretches the lead above his head. As it stretches if
deforms (changes shape).
Ed thinks he is a strong man, little does he realise that lead is a
very soft metal and stretches very easily. He performs these tricks in
local pubs in an attempt to pass himself off as a ‘hard man’.
TENSILE STRENGTH
The ability of a material to stretch without breaking
or snapping.
Our technology technician demonstrates ‘tensile strength’ by stretching
a piece of steel until it snaps. Ed thinks he is incredibly strong.
However, his friends at work have substituted a sausage in place of the
steel.