1.6 - Material Properties

Forces and stresses and Physical and Working properties

Forces and stresses

forces act on materials all the time - even if a material appears stationary it can still have a force acting on it. These are five terms used to describe what type of force can act on a material.

tension

pulling force

compression

pushing force

bending

forces at an angle to the material

torsion

twisting force

shear

forces acting across the material.

Physical and Working Properties

physical properties are the traits a material has before it is used. working properties are how a material behaves when it is manipulated

physical properties

absorbency

the ability to soak up moisture, light or heat, eg natural materials (such as cotton or paper) tend to be more absorbent than man-made materials (such as acrylic or polystyrene)

density

how solid a material is. This is measured by dividing mass (grams) by volume (cm³), eg lead is a dense material

fusibility

the ability of a material to be heated and joined to another material when cooled, eg webbing is fusible and can be ironed onto fabrics

electrical conductivity

the ability to conduct electricity, eg copper is a good conductor of electricity

thermal conductivity

the ability to conduct heat, eg steel is a good heat conductor, whereas pine is not

working properties

strength

the ability of a material to withstand compression, tension and shear, eg in woven fabrics cotton isn’t as strong as wool when pulled

hardness

the ability to withstand impact without damage, eg pine is easier to dent with an impact than oak; therefore, oak is harder

toughness

materials that are hard to break or snap are tough and can absorb shock, eg Kevlar in bulletproof vests is a very tough materialm

malleability

being able to bend or shape easily would make a material easily malleable, eg sheet metal such as steel or silver is malleable and can be hammered into shape.

ductility

materials that can be stretched are ductile, eg pulling copper into wire shows it is ductile

elasticity

the ability to be stretched and then return to its original shape, eg elastane in swimming costumes is a highly elastic material