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Reg. No. :

M.E./M.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2011.

Common to M.E. – Computer Aided Design /M.E. Engineering Design/

M.E. – Product Design and Development

Elective

220075 — COMPOSITE MATERIALS AND MECHANICS

(Regulation 2010)

Time : Three hours Maximum : 100 marks

Answer ALL questions.

PART A — (10 × 2 = 20 marks)

1. Define Rule of Mixtures in the determination of elasticity modulus.

2. Name the precursors used in the manufacturing of carbon fibers.

3. Calculate fV and cρ for a composite laminate containing 30% weight of

E-glass fibers in a polyester resin. Assume 54.2=fρ g/ml and g/ml1.1=mρ .

4. Discuss the effects of interface bonding on properties of composite.

5. What are three common modes of failure of a unidirectional composite

subjected to Longitudinal tensile load?

6. Define strength ratio.

7. Write down the equilibrium equations for bending of laminated plates.

8. Mention the stiffness parameter on which the buckling load depends? Why a

cross ply is preferred for higher buckling load.

9. What do you mean by Warpage in Laminates?

10. What is thermal Spiking?

PART B — (5 × 16 = 80 marks)

11. (a) (i) Explain in detail the general characteristics of composite materials

and state some of its application? (12)

(ii) What are the commercial forms of fiber available and mention its

importance in the evaluation of elastic properties. (4)

Or

Question Paper Code : 33209

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33209 2

(b) With neat sketches explain :

(i) Pultrusion (8)

(ii) Filament Winding. (8)

12. (a) Determine the stiffness matrices [A], [B] and [D] for a

s]45/45[ −+ symmetric laminate. The properties for the fiber are

Gpa220Ef = ; 2.0=fγ ; 6.0=fV and for the matrix are 3.6Em = GPa;

35.0=mγ . Each lamina is 6 mm thick.

Or

(b) Derive the A, B and D matrices of a laminate.

13. (a) Discuss in detail the following failure theories and specify the advantages

of each over the other.

(i) Maximum Stress Failure theory

(ii) Maximum Strain Failure Theory

(iii) Tsai- Hill Failure Theory

(iv) Tsai- Wu Failure Theory

Or

(b) Find the maximum value of 0>S by using Tsai-Hill Failure Theory and

compare it with Tsai-Wu Failure Theory, if a stress of Sxx 2=σ ,

Syy 3−=σ and Sxy 4=τ is applied to a 60° graphite/epoxy lamina. The

lamina properties are

( ) 150011 =ult

Tσ MPa; ( ) 150011 =ult

Cσ MPa; ( ) 4022 =ult

Tσ MPa;

( ) 24622 =ult

Cσ MPa; ( ) 6812 =ult

τ MPa.

14. (a) Derive the governing differential equation for buckling of simply

supported laminated rectangular plate along the edges X = 0, X = a, Y = 0

and Y = b subjected to inplane force in X direction, XN .

Or

(b) Find the deflection of a thin square laminated plate of size 50 × 50 mm

consisting of four layers [0/90/90/0] of equal thickness with b/h = 100

having all edges simply supported. The properties of a graphite/epoxy

laminated plate are listed below :

181E11 = GPa; 10.30E22 = GPa; 28.012 =γ ; 7.17G12 = GPa;

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33209 3

15. (a) Explain the characteristics of the following laminates :

(i) Unidirectional Laminates

(ii) Symmetric Balanced Laminates

(iii) Zero CTE Laminates

(iv) Thermally Quasi — Isotropic Laminates

Or

(b) Calculate the residual stresses at the bottom surface of the 90°ply in a

[0/90] graphite epoxy laminate subjected to a temperature change of

–75°C.The lamina properties are Cmm o//02.01 µα = ,

Cmm o//5.222 µα = the transformed stiffness matrix for o0 and o90 is

given below

[ ]

=17.700

035.10897.2

0897.28.181

0Q GPa [ ] GPa

17.700

08.181897.2

0897.235.10

90

=Q

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