This set of Composite Materials Multiple Choice Questions & Answers (MCQs) focuses on “Reinforcing Phase – Set 2”.
1. Soft property to the composite is given by ________ constituent.
a) Matrix
b) Reinforcement
c) Matrix and reinforcement
d) Fillers
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Explanation: Composites are made up of matrix and reinforcement agent. Matrix acts as a supporting structure which supports the reinforcement agents and transverse the external load onto the reinforcement agents successively. Fillers are solid materials which are introduced on the matrix material for improving a specific property and they also reduce cost and increase physical properties.
2. Strength of a composite is mainly dependent upon ________ constituent.
a) Matrix
b) Reinforcement
c) Matrix and reinforcement
d) Neither matrix and reinforcement
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Explanation: The reinforcement agent has good mechanical property such as tensile, bending, toughness and impact. These properties of reinforcement give a good strength to the composites. Whereas matrix agents help in supporting the reinforcement agents.
3. Which of the following factors of fiber does not affect the mechanical performance of the composites?
a) Length
b) Orientation
c) Material
d) Cost
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Explanation: Each type of fibers has different cost estimation but cost parameter does not have any role in affecting the mechanical performance of the composites. Whereas Length, Orientation and type of Material of the fiber directly affects the mechanical performance of the composites.
4. With regards to composites PAN can abbreviated as __________
a) Permanent Account Number
b) Personal Area Network
c) Polyarteritis nodosa
d) Polyacrylonitrile
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Explanation: Polyacrylonitrile is one the precursor used for the manufacturing of the graphite fibers. Whereas Permanent Account Number, Personal Area Network and Polyarteritis nodosa are the abbreviation used in Banking, Networking and Medical sectors.
5. Which of the following stage is not used in the manufacturing of a carbon fiber from PAN-based precursors.
a) Stabilization
b) Polymerization
c) Carbonization
d) Graphitization
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Explanation: The process of addition of monomers to form polymers is called Polymerization. Stabilization is the first process used in the manufacturing of carbon fibers from PAN-based precursor where fiber is passed through a furnace between 200 and 300°C, Carbonization is the second process where the fiber is pyrolysed at 1000 and 1500°C and Graphitization is the final process where the fibers are heat treated at 2500°C.
6. Weight percentage of SiO2 in E-Glass is ___________
a) 14.5
b) 17
c) 54.5
d) 4.5
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Explanation: 54.5% of SiO2 is present in E-Glass. Glass fibers are amorphous (non-crystalline) and isotropic in nature. E-Glass by weight has 14.5, 17 and 4.5% of Al2O3, CaO and MgO in its composition.
7. A lamina (also called a ply or layer) is a single flat layer of unidirectional fibers or woven fibers arranged in a matrix.
a) True
b) False
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Explanation: Structures obtained with layer by layer arrangement of laminas are called Laminates. Fibers in laminas are unidirectional but these are arranged in different angles to give maximum strength to the laminates.
8. Matrix agents does not contribute in increasing the mechanical performance of the composites.
a) True
b) False
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Explanation: Maximum strength to the composite is mainly given by reinforcing phase but matrix phase also contributes in increasing the mechanical property by distributing the loads on reinforcing agents.
9. __________ has uniform properties throughout it.
a) Inhomogeneous body
b) Homogeneous body
c) Isotropic body
d) Anisotropic body
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Explanation: A Homogeneous body has uniform properties throughout, i.e., the properties are independent of position in the body. An Inhomogeneous body has nonuniform properties over the body, i.e., the properties depend on position in the body. An Isotropic body has material properties that are the same in every direction at a point in the body, i.e., the properties are independent of orientation at a point in the body. An Anisotropic body has material properties that are different in all directions at a point in the body. No planes of material property symmetry exist.
10. Body with material properties that are different in three mutually perpendicular directions at a point in the body and further has three mutually perpendicular planes of material property symmetry are called as ________
a) Orthotropic materials
b) Anisotropic materials
c) Non-homogeneous materials
d) Isotropic materials
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Explanation: An Anisotropic body has material properties that are different in all directions at a point in the body. No planes of material property symmetry exist. An Inhomogeneous (also called as non-homogeneous or heterogeneous) body has nonuniform properties over the body, i.e., the properties depend on position in the body. An Isotropic body has material properties that are the same in every direction at a point in the body, i.e., the properties are independent of orientation at a point in the body.
11. Along with carbon fiber which of the following fiber has negative coefficient of thermal expansion in longitudinal direction?
a) Boron fiber
b) Aramid fiber
c) Jute fiber
d) Sisal fiber
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Explanation: Aramid fiber has negative coefficient of thermal expansion in longitudinal direction, which is used in designing low thermal expansion composite panels. The major disadvantages of aramid fiber-reinforced composites are their low compressive strengths and difficulty in cutting or machining. Boron fiber, jute fiber and sisal fiber are some of the reinforcing agents.
12. Molecular structure of Aramid fiber is made up of _________ and ________
a) Aromatic ring and hydrogen
b) Aromatic ring and amide groups
c) Aromatic ring and Nitrogen
d) Aromatic ring and NH2
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Explanation: Aramid fiber also called as Kevlar 49 is made up of aromatic ring and amide groups. Aromatic rings are planar rings with atoms attached with two different covalent bonds. (-NH) groups are called amide groups.
13. S.I unit of strain is _______
a) N/m2
b) N-m
c) Unit less
d) m2
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Explanation: Strain of a material can be defined as the ratio of deformation in the direction of applied load to the initial length. N/m2, N-m and m2 are the S.I units of Pressure, work done and area respectively.
14. Materials which can reshape to any structure on the application of heat or pressure are called as _____
a) Thermoset materials
b) Elastomers
c) Thermoplastic materials
d) Thermoforming materials
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Explanation: Thermoplastic materials are linear or branched chain molecules having strong intramolecular bonds but weak intermolecular bonds. Whereas Thermosets have cross-linked or network structures with covalent bonds with all molecules. They do not soften but decompose on heating and do reshape into any structure. Elastomers are polymers with both elasticity and viscosity property.
15. ASTM stands for ___________
a) American Standard for Testing of Materials
b) American Society for Testing and Materials
c) African Standard for Testing of Materials
d) Average Stress Testing Machine
View Answer
Explanation: American Society for Testing and Materials is an international standards organization which sets technical standards for various materials, services, products and systems.
Sanfoundry Global Education & Learning Series – Composite Materials.
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