Composite Materials

Question 1

What is a composite ?

Answer 1

A composite material consists of two or more distinct phases, typically a matrix and a reinforcing phase, combined to create a material with superior properties compared to the individual components

Question 2

What is the difference between blends and composites?

Answer 2

In composites, individual phases remain recognizable, while in blends, the phases mix without being easily distinguishable.

Question 3

List the three main types of composites based on the matrix material .

Answer 3

1. Polymer Matrix Composites (PMC)
2. Metal Matrix Composites (MMC)
3. Ceramic Matrix Composites (CMC)

Question 4

What is the “Rule of Mixtures” in composite design?

Answer 4

The Rule of Mixtures states that certain properties of a composite material, such as modulus of elasticity are the weighted average of the properties of its components based on their volume fractions.

Question 5

Mention two examples of natural composites ?

Answer 5

Wood- composed of cellulose fibers embedded in a lignin matrix

Bone- A combination of collagen fibers and hydroxyapatite

Question 6

What are the main advantages and disadvantages of composite materials?

Answer 6

Advantages: Lightweight ; Corrosion resistance ; High fatigue strength

Disadvantages: Low recyclability ; Expensive; Matrix degradation over time

Question 7

How do continuous and discontinuous fibers differ in composites ?

Answer 7

Continuous fibers: Provide a continuous path for stress transfer resulting in higher strength

Discontinuous fibers: short fibers with high strength used where isotropic properties are required.

Question 8

Give examples of applications for polymer matrix composites

Answer 8

Aircraft structures
Medical equipment
Automotive body panels
Printed circuit boards