Lecture 4

Question 1

Composite materials have a —— which is usually the surrounding/continuous material

Answer 1

matrix

Question 2

If an additional material is added to increase the mechanical properties, they are referred to as

Answer 2

reinforcements

Question 3

Particulates consist of —— – ——- dispersed within the ——

Answer 3

particles of material, matrix

Question 4

Thee types of classification of composites:

Answer 4

• particulate
• fibre
• laminar

Question 5

Fibre composites consist of

Answer 5

fibres of the reinforcing material dispersed in the matrix

Question 6

Laminar composites are based on

Answer 6

sheets laminated together such as plywood

Question 7

Specific properties examples 2

Answer 7

• specific strength
• specific modulus

Question 8

Specific strength =

Answer 8

tensile strength / density

Question 9

Specific modulus =

Answer 9

elastic modulus / density

Question 10

Glass fibre reinforced polymer is simplified to ——- and is AKA ——-

Answer 10

GFRP, fibreglass

Question 11

Metal matrix composites are

Answer 11

metals strengthened by the addition of ceramic material fibres

Question 12

Aramid fibre reinforced polymer is made up of

Answer 12

aramid fibres in an epoxy or polyester matrix

Question 13

Continuous fibres oriented in one direction, in parallel lines, give —— properties

Answer 13

anisotropic

Question 14

Continuous fibres oriented in two directions, crossing over each other perpendicular to each other, give —— —— properties

Answer 14

more uniform

Question 15

Discontinuous fibres oriented in one direction, parallel to eachother, give ———

Answer 15

anisotropic

Question 16

Discontinuous fibres oriented in random directions give ——- properties

Answer 16

isotropic

Question 17

In a fibre matrix, the matrix is usually the materials which is

Answer 17

• low cost
• poor specific properties

Question 18

In a fibre matrix, the fibres are often the material which is

Answer 18

• more expensive
• superior specific properties

Question 19

The matrix material performs the role of (5)

Answer 19

• transfers loads to fibres
• holds the fibres in place
• prevents fibres to —?
• protects the fibres from corrosion and mechanical damage

Question 20

Mechanical bonding is when the matrix and fibres are joined by

Answer 20

interlocking of component surfaces or frictional resistance

Question 21

Adhesive bonding is when the matrix is joined to the fibre by

Answer 21

chemical reactions at the interface

Question 22

Reaction bonding is when the matrix is joined to the fibres by

Answer 22

the components reacted together at the interface creating a new chamical compound

Question 23

Poor adhesion in a fibre matrix can lead to the fibre

Answer 23

not being joined to the matrix and leading to the matrix taking the stress load applied rather than the fibre taking any of the force

Question 24

Fibres can be discontinuous but their —— —— depend on their length

Answer 24

reinforcement properties

Question 25

l c =

Answer 25

critical fibre length =

(σf d) / 2 τi

(fibre strength X diameter of the fibre) / 2 strength of the interface between matrix and fibre surface