GTU BE 2019 Summer Question Papers || Gujarat Technological University
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Subject Code:2170107
GUJARAT TECHNOLOGICAL UNIVERSITY
Subject Name:Mechanics of Composite Materials
Time:02:30 PM TO 05:00 PM Date:16/05/2019 Total Marks: 70
Instructions:
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Subject Code:2170107
GUJARAT TECHNOLOGICAL UNIVERSITY
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BE - SEMESTER-VII(NEW) EXAMINATION - SUMMER 2019Subject Name:Mechanics of Composite Materials
Time:02:30 PM TO 05:00 PM Date:16/05/2019 Total Marks: 70
Instructions:
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
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| Q.1 (a) | What is the limitation of a unidirectional lamina? How it can be overcome by laminate? Explain with neat sketch. | MARKS 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 pf = 2.50 g/ml and pm = 1 g/ml. Calculate Vf and p for the lamina. | 04 |
| (c) | Identify the types of laminate given below. [0/30/60]S [0/90/0/90] --- Content provided by FirstRanker.com --- [—40/40/—40/40][45/60/—60/—45] [30/40/—30/30/—30/=40] [0/160] [0/90]S | 07 |
| Q.3 (a) | Evaluate the transverse modulus E2 of a composite lamina by (i) strength of material approach and (ii) Halpin-Tsai relation, with the following properties E1 = 14.8 GPa, E2 = 3.45 GPa, v12 = 0.36, Vf =0.65. Assume ?=1. | 07 |
| (b) | Explain about symmetric laminate. | 03 |
| (c) | Derive the equation of Inplane Shear modulus using neat sketches. | 04 |
| Q.3 (a) | Derive Strain-Displacement relationship of a laminate using a neat sketch. | 07 |
| (b) | What do you mean by balanced laminate. | 03 |
| (c) | Derive the equation of Transverse modulus with the use of neat sketches. | 04 |
| Q4 (a) | Write down [A], [B] and [D] matrices and explain its significance in detail. | 07 |
| (b) | Write down the difference between micromechanics and macromechanics. | 03 |
| (c) | A glass/epoxy specimen was immersed in water for 24 hours 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 |
| Q4 (a) | Explain about prepregs. | 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.S (a) | Reduced stiffness matrix of an orthotropic lamina is given by, --- Content provided by FirstRanker.com --- [Q] =Determine E1, E2, G12 and v12. | 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 |
| Q.S (a) | For an orthotropic lamina, engineering constants along the principal material axis are E1 = 150 GPa, E2 = 20 GPa, G12 =5 GPa, v12 = 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/mm² and v = 0.25. Determine reduced stiffness matrix and reduced compliance matrix. | 07 |
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