Download GTU BE/B.Tech 2018 Winter 7th Sem New 2170107 Mechanics Of Composite Materials Question Paper

FirstRanker.com

GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER-VII (NEW) EXAMINATION - WINTER 2018

--- Content provided by‌ FirstRanker.com ---

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.

--- Content provided by⁠ FirstRanker.com ---

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 03
used in a composite.

--- Content provided by⁠ FirstRanker.com ---

(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

--- Content provided by⁠ FirstRanker.com ---

(b) Define Poisson’s ratio and derive the rule of mixtures for 04
major Poisson’s ration.
(c) Using strength of material approach to derive the relation for 07
transverse modulus of a unidirectional composite. Also write
Halphin-Tsai relations for evaluation of transverse modulus

--- Content provided by‌ FirstRanker.com ---

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 04
lamina in terms of densities of its constituents.

--- Content provided by‍ FirstRanker.com ---

(c) Explain in detail Anti-Symmetric laminates 07

OR

Q.3 (a) Explain the purpose of prepegs and fillers in composite 03
materials
(b) Give classification of laminate configuration 04

--- Content provided by‍ FirstRanker.com ---

(c) Find the minor and major Poisson’s ratio of a Glass/Epoxy 07
lamina with a 70 percent fibre volume fraction. Use vf = 0.2
Vm = 0.3, Ef=85GPa and Em = 3.4 GPa

Q.4 (a) Write the disadvantages of composite material. 03
(b) Determine the reduced Stiffness matrix [Q] for an orthotropic 04

--- Content provided by​ FirstRanker.com ---

lamina with the following material properties. E1 = 150 GPa,
E2=20 GPa, G12=5 GPa and v12=0.3
(c) The longitudinal modulus of a Glass Reinforced Plastic (GRP) 07
lamina is to be doubled by substituting some of the glass fibres
with carbon fibres. The total fibre volume remains unchanged

--- Content provided by‍ FirstRanker.com ---

at 0.5. Calculate the fraction of carbon fibres.
Use Ecarbon= 300 GPa, Eg = 70 GPa and Em = 5 Gpa

OR

Q.4 (a) Discuss the role of fibres and matrix in composite material 03

FirstRanker.com

--- Content provided by​ FirstRanker.com ---

List and briefly the following laminates with reference to the following stacking sequences:
i. [0/90]s
ii. [-45/45]s
iii. [0/90]s
iv. [-45/0/45/90]s

--- Content provided by​ FirstRanker.com ---

(c) Derive the stress-strain relationship for a specially orthotropic 07
composite material.

Q.5 (a) Sketch the variation of stress and strain in a laminate 03
(b) Calculate the longitudinal modulus and tensile strength of a 04
unidirectional composite containing 60 percent by volume

--- Content provided by‌ FirstRanker.com ---

fraction of carbon fibres. Use Eir = 3.6 GPa and omu = 105
MPa. Compare these values with experimentally determined
values of E1 = 162GPa and omu = 2.94 GPa. What fraction of
the load is carried by the fibres in the composite?
(c) Stating the necessary assumptions made in laminate theory, 07

--- Content provided by⁠ FirstRanker.com ---

derive the strain displacement relation for a laminate.

OR

Q.5 (a) List the four elastic moduli of unidirectional lamina. Also list 03
the different methods used to determine them.
(b) Derive the relation for inplane shear modulus using the 04

--- Content provided by⁠ FirstRanker.com ---

strength of material approach.
(c) Calculate the matrices [A] and [B] for a cross-ply laminate 07
[0/90] with the following lamina properties. E1 = 140 GPa ,
E2= 10 GPa, G12 = 5GPa v12 = 0.3. Use ply thickness, d =
0.125mm

--- Content provided by FirstRanker.com ---

FirstRanker.com