22-08-2012, 02:44 PM
MECHANICS OF COMPOSITE MATERIALS Supplementary Examinations
1Supplementary Examinations.pdf (Size: 106.86 KB / Downloads: 69)
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.
b) Determine Poisson’s ratio xyυat angle with the fibre direction for a material with the following properties: 030θ=
112223,0.5EGEE== and 120.25υ=.
3.a) How carbon fibres are made? Describe with sketches a typical fabrication process.
b) 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?
b) Determine the mechanical coupling terms in a []20/90 laminate with the following lamina properties:
E1 =140 Gpa, E2 = 10 Gpa, G12 = 4 Gpa and 120.26υ=
Take each lamina thickness as 1 mm.
6. Describe briefly the characterisation test methods for a uni directional lamina.
7. 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 ()0245± laminate. 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 short notes on:
i) Metal matrix composites
ii) Kirchoff’s assumptions
iii) Show that offonQTQTσ−