Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 7th Sem New 2170107 Mechanics Of Composite Materials Previous Question Paper
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VII (NEW) EXAMINATION ? WINTER 2018
Subject Code: 2170107 Date: 26/11/2018
Subject Name: Mechanics of Composite Materials
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) What is composite material? List the types of reinforcement
used in a composite.
03
(b) Explain the mechanical behavior of composites. 04
(c) Differentiate between Micromechanics and Macromechanics. 07
Also mention the assumptions made in typical
Micromechanical analysis.
Q.2 (a) Explain the use of composite materials in Aircraft industry 03
(b) Define Poisson?s ratio and derive the rule of mixtures for
major Poisson?s ration.
04
(c) Using strength of material approach to derive the relation for
transverse modulus of a unidirectional composite. Also write
Halphin-Tsai relations for evaluation of transverse modulus
07
OR
(c) Explain in detail Symmetric laminates 07
Q.3 (a) Differentiate between Lamina and Laminate with neat sketches 03
(b) Derive an expression for density of a unidirectional composite
lamina in terms of densities of its constituents.
04
(c) Explain in detail Anti-Symmetric laminates 07
OR
Q.3 (a) Explain the purpose of prepegs and fillers in composite
materials
03
(b) Give classification of laminate configuration 04
(c) Find the minor and major Poisson?s ratio of a Glass/Epoxy
lamina with a 70 percent fibre volume fraction. Use ?12f = 0.2
?m = 0.3 Ef = 85GPa and Em = 3.4 GPa
07
Q.4 (a) Write the disadvantages of composite material. 03
(b) Determine the reduced Stiffness matrix [Q] for an orthotropic
lamina with the following material properties. E1 = 150 GPa,
E2 = 20 GPa, G12 = 5 GPa and ?12 = 0.3
04
(c) The longitudinal modulus of a Glass Reinforced Plastic (GRP)
lamina is to be doubled by substituting some of the glass fibres
with carbon fibres. The total fibre volume remains unchanged
at 0.5. Calculate the fraction of carbon fibres.
Use Ecarbon= 300 GPa, Eg = 70 GPa and Em = 5 Gpa
07
OR
Q.4 (a) Discuss the role of fibres and matrix in composite material 03
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VII (NEW) EXAMINATION ? WINTER 2018
Subject Code: 2170107 Date: 26/11/2018
Subject Name: Mechanics of Composite Materials
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) What is composite material? List the types of reinforcement
used in a composite.
03
(b) Explain the mechanical behavior of composites. 04
(c) Differentiate between Micromechanics and Macromechanics. 07
Also mention the assumptions made in typical
Micromechanical analysis.
Q.2 (a) Explain the use of composite materials in Aircraft industry 03
(b) Define Poisson?s ratio and derive the rule of mixtures for
major Poisson?s ration.
04
(c) Using strength of material approach to derive the relation for
transverse modulus of a unidirectional composite. Also write
Halphin-Tsai relations for evaluation of transverse modulus
07
OR
(c) Explain in detail Symmetric laminates 07
Q.3 (a) Differentiate between Lamina and Laminate with neat sketches 03
(b) Derive an expression for density of a unidirectional composite
lamina in terms of densities of its constituents.
04
(c) Explain in detail Anti-Symmetric laminates 07
OR
Q.3 (a) Explain the purpose of prepegs and fillers in composite
materials
03
(b) Give classification of laminate configuration 04
(c) Find the minor and major Poisson?s ratio of a Glass/Epoxy
lamina with a 70 percent fibre volume fraction. Use ?12f = 0.2
?m = 0.3 Ef = 85GPa and Em = 3.4 GPa
07
Q.4 (a) Write the disadvantages of composite material. 03
(b) Determine the reduced Stiffness matrix [Q] for an orthotropic
lamina with the following material properties. E1 = 150 GPa,
E2 = 20 GPa, G12 = 5 GPa and ?12 = 0.3
04
(c) The longitudinal modulus of a Glass Reinforced Plastic (GRP)
lamina is to be doubled by substituting some of the glass fibres
with carbon fibres. The total fibre volume remains unchanged
at 0.5. Calculate the fraction of carbon fibres.
Use Ecarbon= 300 GPa, Eg = 70 GPa and Em = 5 Gpa
07
OR
Q.4 (a) Discuss the role of fibres and matrix in composite material 03
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2
(b) Identify the following types of laminate:
i. [0|902|0|90]
ii. [-45|45|-45|45]
iii. [0|90]s
iv. [-45|0|45|90]s
04
(c) Derive the stress-strain relationship for a specially orthotropic
composite material.
07
Q.5 (a) Sketch the variation of stress and strain in a laminate 03
(b) Calculate the longitudinal modulus and tensile strength of a
unidirectional composite containing 60 percent by volume
fraction of carbon fibres. Use E1f = 3.6 GPa and ?mu = 105
MPa. Compare these values with experimentally determined
values of E1 = 162GPa and ?mu = 2.94 GPa. What fraction of
the load is carried by the fibres in the composite?
04
(c) Stating the necessary assumptions made in laminate theory,
derive the strain displacement relation for a laminate.
07
OR
Q.5 (a) List the four elastic moduli of unidirectional lamina. Also list
the different methods used to determine them.
03
(b) Derive the relation for inplane shear modulus using the
strength of material approach.
04
(c) Calculate the matrices [A] and [B] for a cross-ply laminate
[0|90] with the following lamina properties. E1 = 140 GPa ,
E2= 10 GPa, E6 = 5GPa ?12 = 0.3. Use ply thickness, d =
0.125mm
07
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This post was last modified on 20 February 2020