This set of Composite Materials Multiple Choice Questions & Answers (MCQs) focuses on “Manufacturing Fundamentals”.
1. Which of the following is a composite material?
a) Carbon fiber
b) Steel
c) Glass
d) Aluminium
View Answer
Explanation: Carbon fiber is a composite material while Steel, Glass, Aluminium are alloy, ceramic and metal respectively. Composites are the material which consists of a matrix phase and reinforcement phase. The addition of reinforcements helps in enhancing the properties of the material.
2. The _____ provides a good surface finish quality for the composites.
a) reinforcement
b) matrix
c) additive
d) binder
View Answer
Explanation: The matrix is the bulk part of a composite which provides definite shape, surface finish and protection to reinforcing fibers. They bind the fiber together and transfers the load to the fibers.
3. Net shape or near-net shape parts can be produced with composite materials.
a) True
b) False
View Answer
Explanation: Neat net shape is a technique used in industrial manufacturing. It helps in reducing the production cost and process cycle time by eliminating several machining operations since the net shape is very close to the initial shape of the product.
4. Which of the given materials is not a composite?
a) Kevlar
b) Glass fiber
c) Steel
d) Carbon fiber
View Answer
Explanation: Steel is an alloy of Iron (Fe) and Carbon (C). High carbon steel, Mild steel, Medium carbon steel are some of the different types of steel which differs by the composition of the alloying elements.
5. The final properties of composite materials are better than the constituent material properties.
a) True
b) False
View Answer
Explanation: The addition of high strength reinforcement fibers to the matrix phase can help in enhancing the properties like durability, design flexibility, corrosion resistance, chemical resistance, temperature resistance, ultimate tensile strength etc. which makes composite materials better than the base materials.
6. The reinforcing fibers provide strength and stiffness to the composite, whereas the ______ gives the rigidity and environmental resistance.
a) matrix
b) reinforcement
c) adhesives
d) binders
View Answer
Explanation: The matrix is the bulk part of a composite material which binds the reinforcement fibers together and transfers the load to the fibers. It provides rigidity, shape and good surface finish quality and helps in the production of near-net-shape parts. The matrix also protects the fibers from wear and chemical attack.
7. Which is not a function of the composite fibers?
a) To carry the load
b) To provide stiffness
c) To provide electrical conductivity
d) Provides shape to the structure
View Answer
Explanation: The reinforcements also provide strength and thermal stability to the composites. It is the matrix that provides shape to the composites.
8. Composite materials offer low corrosion resistance.
a) True
b) False
View Answer
Explanation: Composites generally offer high corrosion resistance. Because the outer surface of the composites is formed by the plastics, corrosion and chemical resistance are very good.
9. NVH characteristics are better for composite materials than metals. What does NVH stand for?
a) Noise, Vibration, Hardness
b) Noise, Volume, Hardness
c) Noise, Vibration, Harshness
d) Number, Volume, Harshness
View Answer
Explanation: Noise, vibration, and harshness (NVH), also known as noise and vibration (N&V), is the study and modification of the noise and vibration characteristics of vehicles, particularly cars and trucks.
10. What is the primary factor that composite materials are used in aircraft manufacturing?
a) High-temperature resistance
b) Durability
c) High chemical resistance
d) High stiffness to low weight ratio
View Answer
Explanation: The primary reason for the usage of composite material in the aerospace and aircraft industry is because of its lighter weight compared to other materials. The lightweight feature improves performance and fuel efficiency of aircraft, without compromising in the stiffness and impact resistance.
11. Which of the following is the most expensive composite?
a) Carbon fiber
b) Glass fiber
c) Kevlar
d) Glass/epoxy prepreg
View Answer
Explanation: The material costs of composite materials is enormous compared to metals like aluminium and steel. Carbon fiber costs $8 to $40/lb, Glass fiber costs $1 to $8/lb, Kevlar costs $2.85/lb and Glass/epoxy prepreg costs $2.85.
12. Which is not a composite manufacturing process?
a) Resin transfer molding
b) Structural reaction injection molding
c) Pultrusion
d) Shell molding
View Answer
Explanation: Shell molding is used for making metallic castings that require high precision. Shell molding was developed as a manufacturing process during the mid-20th century in Germany. All the other methods are mainly used for composite manufacturing.
13. Composites absorb moisture.
a) True
b) False
View Answer
Explanation: Moisture absorption increases with the weight fraction of the reinforced fibers. This adversely affects the properties and dimensional stability of the composites. The composite may undergo cracking before its expected durability. It will result in the performance of devices, instruments or machines.
14. Which is the correct order of processes in composite manufacturing?
a) Forming, Joining and assembling, machining, finishing
b) Joining and assembling, forming, machining, finishing
c) Forming, machining, joining and assembly, finishing
d) Machining, joining and assembly, forming, finishing
View Answer
Explanation: In forming, the feedstock is changed into the desired shape and size. Machining operations include drilling, turning, cutting and grinding. Joining and assembly are performed to attach different components in a manner so that they can perform a specific task. Finishing operations are performed to improve outside appearance.
15. Which industry is the largest user of composite materials?
a) Sports
b) Construction
c) Marine
d) Transportation
View Answer
Explanation: Transportation industry is the largest user of the composite materials, having consumed around 1.3 billion pounds of composites in 2000. The second comes to the construction, then comes the marine and sports industry in third and fourth positions respectively.
Sanfoundry Global Education & Learning Series – Composite Materials.
To practice all areas of Composite Materials, here is complete set of 1000+ Multiple Choice Questions and Answers.
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