Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Summer 7th Sem New 2170107 Mechanics Of Composite Materials Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VII(NEW) EXAMINATION ? SUMMER 2019
Subject Code:2170107 Date:16/05/2019
Subject Name:Mechanics of Composite Materials
Time:02:30 PM TO 05:00 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 the limitation of a unidirectional lamina? How it can be
overcome by laminate? Explain with neat sketch.
03
(b) Define composite material. Explain basic constituent materials of
composites
04
(c) Carry out the comparison of composite material with metals in
detail.
07
Q.2 (a) Draw a neat sketch of variation of stress and strain through the
thickness of the laminate.
03
(b) The E-glass fibres in a polyester resin is 35% by weight. Given ?? ?? =
2.50 g/ml and ?? ?? = 1 g/ml. Calculate ?? ?? and ?? ?? for the lamina.
04
(c) Identify the types of laminate given below.
1. [0/30/60]
??
2. [0/90
2
/0/90]
3. [?40/40/?40/40]
4. [45/60/?60/?45]
5. [30/40/?30/30/?30/?40]
6. [0/?60]
7. [0/90]
??
07
OR
(c) Evaluate the transverse modulus ?? 2
of a composite lamina by (i)
strength of material approach and (ii) Halpin-Tsai relation, with the
following properties ?? 2?? = 14.8 GPa, ?? ?? = 3.45 GPa, ?? ?? = 0.36, ?? ??
= 0.65. Assume ?? 1
=1.
07
Q.3 (a) Explain about symmetric laminate. 03
(b) Derive the equation of Inplane Shear modulus using neat sketchs. 04
(c) Derive Strain-Displacement relationship of a laminate using a neat
sketch.
07
OR
Q.3 (a) What do you mean by balanced laminate. 03
(b) Derive the equation of Transverse modulus with the use of neat
sketches.
04
(c) Write down [A], [B] and [D] matrices and explain its significance in
detail.
07
Q.4 (a) Write down the difference between micromechanics and
macromechanics.
03
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VII(NEW) EXAMINATION ? SUMMER 2019
Subject Code:2170107 Date:16/05/2019
Subject Name:Mechanics of Composite Materials
Time:02:30 PM TO 05:00 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 the limitation of a unidirectional lamina? How it can be
overcome by laminate? Explain with neat sketch.
03
(b) Define composite material. Explain basic constituent materials of
composites
04
(c) Carry out the comparison of composite material with metals in
detail.
07
Q.2 (a) Draw a neat sketch of variation of stress and strain through the
thickness of the laminate.
03
(b) The E-glass fibres in a polyester resin is 35% by weight. Given ?? ?? =
2.50 g/ml and ?? ?? = 1 g/ml. Calculate ?? ?? and ?? ?? for the lamina.
04
(c) Identify the types of laminate given below.
1. [0/30/60]
??
2. [0/90
2
/0/90]
3. [?40/40/?40/40]
4. [45/60/?60/?45]
5. [30/40/?30/30/?30/?40]
6. [0/?60]
7. [0/90]
??
07
OR
(c) Evaluate the transverse modulus ?? 2
of a composite lamina by (i)
strength of material approach and (ii) Halpin-Tsai relation, with the
following properties ?? 2?? = 14.8 GPa, ?? ?? = 3.45 GPa, ?? ?? = 0.36, ?? ??
= 0.65. Assume ?? 1
=1.
07
Q.3 (a) Explain about symmetric laminate. 03
(b) Derive the equation of Inplane Shear modulus using neat sketchs. 04
(c) Derive Strain-Displacement relationship of a laminate using a neat
sketch.
07
OR
Q.3 (a) What do you mean by balanced laminate. 03
(b) Derive the equation of Transverse modulus with the use of neat
sketches.
04
(c) Write down [A], [B] and [D] matrices and explain its significance in
detail.
07
Q.4 (a) Write down the difference between micromechanics and
macromechanics.
03
2
(b) A glass/epoxy specimen weighing 0.98 gm was burnt and the weight
of the remaining fibres was found to be 0.49 gm. Densities of glass
and epoxy are 2.4 gm/ml and 1.20 gm/ml respectively. Determine
the density of composites in the absence of voids.
04
(c) Discuss the application of composite materials in various
engineering fields.
07
OR
Q.4 (a) Explain about prepegs. 03
(b) Derive the rule of mixtures relation for major Poisson?s ratio and
write expression for minor Poisson?s ratio.
04
(c) Write down the advantages and disadvantages of composite
material.
07
Q.5 (a) Reduced stiffness matrix of an orthotropic lamina is given by,
[?? ] = [
150.81 4.027 0
4.027 20.11 0
0 0 5
] GPa
Determine ?? 1
, ?? 2
, ?? 12
and ?? 12
.
03
(b) Explain the classification of composite materials in detail. 04
(c) How the independent elastic constants have been reduced from 81 to
2 for different materials. Explain in detail with the use of stress-
strain relations and neat sketches.
07
OR
Q.5 (a) For an orthotropic lamina, engineering constants along the principal
material axis are ?? 1
= 150 GPa, ?? 2
= 20 GPa, ?? 12
= 5 GPa, ?? 12
=
0.2. Determine the reduced stiffness matrix [Q].
03
(b) Write down the significance of fillers and additives in composite
materials in detail.
04
(c) Anisotropic lamina has E = 100 kN/mm
2
and ?? = 0.25. Determine
reduced stiffness matrix and reduced compliance matrix.
07
*************
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This post was last modified on 20 February 2020