Engineering material properties

Tensile Strength

• The ability of a material to move

• The ability of a material to stretch without breaking or snapping

• The ability of a material to break or snap

• The ability of a material to stretch

Answer explanation

TENSILE TESTING. A simple workshop test. A piece of material is clamped in a vice. A fixed weight is hung from the end. The amount of deflection, is a measure of its resistance and tensile strength. A selection of materials of the same section, cut to exactly the same size, can be tested in this way.

Elasticity

• The Ability of a material to absorb force and flex in multiple directions

• The Ability of a material to absorb force and flex in different directions, returning to its original position

• The Ability of a material to absorb force and flex in one direction

• The Ability of a material to absorb force and flex along its length

Answer explanation

A simple workshop test. A piece of material is clamped in a vice. A fixed weight is hung from the end and the material bends / deflects. When the weight is quickly removed, the material ‘springs back’. The amount of deflection, is a measure of its elasticity. A selection of materials of the same section, cut to exactly the same measurements, can be tested in this way.

Hardness

• The ability of a material to be scratched

• The ability of a material to last over time

• The ability of a material to resist scratching, wear and tear and indentation

• The ability of a material to change shape

Answer explanation

A method of measuring the hardness of a material, is to drop a ‘plug’ down a tube. When the ‘plug’ hits the material below, the surface will suffer an indent. The indent produced on different materials, can be compared. Consequently, the smaller the indent, the harder the material

Toughness

• The ability of a material to break or shatter

• The ability of a material to absorb light

• The ability of a material to absorb moisture without breaking or shattering

• The ability of a material to absorb sudden shock without breaking or shattering

Answer explanation

The industrial device below measures toughness. The pendulum is allowed to ‘swing’ from a set starting position. The resulting ‘distortion’ to the sample material can be measured on the scale. This gives an indication of the materials toughness.

 

Malleability

• The ability of a material to be reshaped in one direction without cracking​

• The ability of a material to be reshaped along its width without cracking​

• The ability of a material to be reshaped in all directions without cracking​

• The ability of a material to be reshaped along its length without cracking​

Answer explanation

Test: A piece of tube is placed over a piece of material and used as a lever. The material is folded to 90 degrees. Cracks / damage on the inside of the bend represents a lack of malleability.

 

Ductility

• The ability of a material to change shape (deform) usually by stretching along its length​

• The ability of a material to change shape (deform) usually by stretching along its width​

• The ability of a material to reduce in size

• The ability of a material to change weight by stretching along its length​

Answer explanation

A piece of tube is placed over a piece of material and used as a lever. The material is folded to 90 degrees. Cracks / damage on the outside of the bend represents a lack of ductility.

Conductivity

• The ability of a material to melt

• The ability of a material to generate electricity

• The ability of a material to conduct electricity or heat

• The ability of a material to generate heat

Answer explanation

1. A test for electrical conductivity: A voltmeter is used to measure resistance. The probes are set to the same distance on each sample. The resistance is a measure of the materials conductivity.

2. A test for heat conductivity/transfer: A bunsen burner is placed at one end of a piece of material and a temperature meter at the other end. The time it takes for the temperature to change at the opposite end of the material is recorded. If a selection of materials of the same length and section are tested in this way, their conductivity can be compared.

The ability to conduct heat is

• Ductility

• Fusibility

• Thermal Conductivity

• Electrical conductivity

Which of the following material is a good conductor of electricity?

• Thermoset polymers

• Rubber

• Copper

• Pine