Composites: Properties, Applications, and Engineering Significance

Question 1

What is the term for the process of aligning the fibers in a composite material in a specific direction?

Accepted Answer

Lay-up

Answer

Fabrication

Answer

Weaving

Answer

Curing

Question 2

What is the primary factor responsible for the high strength of carbon fiber-reinforced composites?

Accepted Answer

High modulus of elasticity of carbon fibers

Answer

Strong bonding between carbon fibers and the matrix

Answer

Low density of carbon fibers

Answer

Brittle nature of carbon fibers

Question 3

What is the main difference between a laminate and a sandwich composite structure?

Accepted Answer

Laminates have parallel layers of reinforcement, while sandwich structures have a core material between two outer skins.

Answer

Laminates are isotropic, while sandwich structures are anisotropic.

Answer

Laminates are used in aerospace applications, while sandwich structures are used in marine applications.

Answer

Laminates are cheaper to manufacture than sandwich structures.

Question 4

Why is it important to consider the environmental impact of composite materials?

Accepted Answer

To ensure sustainability and minimize pollution

Answer

To comply with environmental regulations

Answer

To reduce manufacturing costs

Answer

To improve the durability of composites

Question 5

Which of the following is NOT an advantage of composite materials?

Accepted Answer

Enhanced toughness

Answer

High strength-to-weight ratio

Answer

Corrosion resistance

Answer

Design flexibility

Question 6

Which of the following industries does NOT typically utilize composite materials?

Accepted Answer

Mining

Answer

Aerospace

Answer

Automotive

Answer

Electronics

Question 7

What is the primary mechanism for strengthening in fiber-reinforced composites?

Accepted Answer

Bonding between the fibers and matrix

Answer

Chemical reactions between the fibers and matrix

Answer

Mechanical interlocking between the fibers and matrix

Answer

Thermal expansion of the fibers

Question 8

What is the purpose of a release agent in composite manufacturing?

Accepted Answer

To prevent the composite from adhering to the mold

Answer

To promote bonding between the composite and mold

Answer

To increase the curing rate of the composite

Answer

To reduce the surface roughness of the composite

Question 9

What is the difference between a unidirectional and a bidirectional composite?

Accepted Answer

Unidirectional composites have fibers aligned in one direction, while bidirectional composites have fibers aligned in two perpendicular directions.

Answer

Unidirectional composites have fibers aligned in two perpendicular directions, while bidirectional composites have fibers aligned in one direction.

Answer

Unidirectional composites are stronger than bidirectional composites in all directions.

Answer

Bidirectional composites are stronger than unidirectional composites in all directions.

Question 10

Which of the following is NOT a type of composite material?

Accepted Answer

Metallic glass composites (MGCs)

Answer

Polymer matrix composites (PMCs)

Answer

Metal matrix composites (MMCs)

Answer

Ceramic matrix composites (CMCs)

Question 11

Which of the following is the main reinforcement phase in fibre-reinforced composites?

Accepted Answer

Fibres

Answer

Matrix

Answer

Additives

Answer

Fillers

Question 12

What is the name of the test used to determine the interlaminar shear strength of composites?

Accepted Answer

Short beam shear test

Answer

Tensile test

Answer

Flexural test

Answer

Compression test

Question 13

What is the primary advantage of using composite materials?

Accepted Answer

High strength-to-weight ratio, enabling lightweight and strong structures

Answer

Low cost, making them affordable for various applications

Answer

Ease of manufacturing, simplifying production processes

Answer

High ductility, allowing for significant deformation without failure

Question 14

What is the role of the matrix in a composite material?

Accepted Answer

Both (b) and (c), emphasizing the dual functions of the matrix

Answer

To provide strength and stiffness, supporting the reinforcement

Answer

To transfer load to the reinforcement, ensuring effective load-bearing

Answer

To protect the reinforcement, shielding it from environmental factors and damage

Question 15

Which of the following factors affects the strength of a fiber-reinforced composite?

Accepted Answer

All of the above, highlighting the interconnected factors that influence composite strength

Answer

Fiber orientation, influencing the load-bearing capabilities

Answer

Fiber volume fraction, determining the amount of reinforcement in the material

Answer

Matrix properties, affecting the overall strength and stiffness of the composite

Question 16

What is the purpose of a lamination process in composite manufacturing?

Accepted Answer

To increase strength by combining multiple layers of material

Answer

To reduce weight by utilizing lightweight materials in the laminates

Answer

To improve surface finish, enhancing the aesthetics and functionality of the composite

Answer

To enhance corrosion resistance, protecting the composite from environmental degradation

Question 17

What is the difference between a unidirectional and a cross-ply laminate?

Accepted Answer

Fiber orientation: unidirectional has fibers aligned in one direction, while cross-ply has fibers in multiple directions

Answer

Matrix content: unidirectional has a higher matrix content, while cross-ply has a lower matrix content

Answer

Reinforcement type: unidirectional uses continuous fibers, while cross-ply uses short fibers

Answer

Manufacturing process: unidirectional is manufactured using a pultrusion process, while cross-ply is manufactured using a molding process