53106-mt----mechanics Of Composite Materials

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Code No: 53106/MT M.Tech. – I Semester Supplementary Examinations, September, 2008 MECHANICS OF COMPOSITE MATERIALS (Machine Design) Time: 3hours

Max. Marks:60 Answer any FIVE questions All questions carry equal marks ---

1.

How do you classify the fibre reinforced composites based on the matrix used? Explain each category.

2.a)

Describe the significance and objectives of composite material science and Technology. Determine Poisson’s ratio υ xy at angle θ = 300 with the fibre

b)

direction for a material with the following properties: E1 G = 3, 12 = 0.5 and υ12 = 0.25 . E2 E2 3.a) b)

How carbon fibres are made? Describe with sketches a typical fabrication process. Obtain the relation for a strain at any point in the laminate to the reference plane strains and the laminate curvatures using classical lamination theory.

4.)

Derive the Tsai-Hill and Tsai-Wu strength criteria for a composite lamina.

5.a)

What are mechanical coupling terms in laminate stiffnesses? How do they influence the mechanical behaviour of a laminate? Determine the mechanical coupling terms in a [ 0 / 90]2 laminate

b)

with the following lamina properties: E1 =140 Gpa, E2 = 10 Gpa, G12 = 4 Gpa and υ12 = 0.26 Take each lamina thickness as 1 mm. 6.

Describe briefly the characterisation test methods for a uni directional lamina. Contd…2

Code No: 53106/MT 7.

::2::

A closed cylindrical pressure vessal of mean radius of 1m is subjected to an internal pressure of 0.5 KN/cm2. The wall of the vessel has a thickness of 4 mm and is made of a ( ±450 ) laminate. 2

The properties of a

450

lamina are as fallows:

QM = 27 Gpa, Q66 = 23 Gpa Q22 = 27 Gpa, Q16 = 22 Gpa Q12 = 22 Gpa, Q26 = 22 Gpa Determine the top ply stresses. 8.)

Write i) ii) iii)

short notes on: Metal matrix composites Kirchoff’s assumptions Show that Q  off = Tσ−  Q  on T∈+  *****