Pune University BE Polymer Processing of Composities Question Papers

Pune University Previous Question Paper

B.E. (Polymer) PROCESSING OF COMPOSITES (2008 Pattern)

(Elective – III) (Sem. – II)

Time : 3 Hours]                                                                                            [Max. Marks : 100

Instructions to the candidates:

1)         Answer three questions from section-I and three questions from section-II.

2)         Answers to the two sections should be written in separate books.

3)          Neat diagrams must be drawn wherever necessary.

4)          Figures to the right indicate full marks.

5)          Your answers will be valued as a whole.

6)          Use of logarithmic tables slide rule, Mollier charts, electronic pocket calculator and steam tables is allowed.

7)        Assume suitable data, if necessary.

SECTION – I

QI) a) Discuss the different types of glass filers commonly used. What are the advantages and disadvantages of glass fibers?                                                                          [6]

b)             Assuming that the unidirectional continuous fibers of round corss-section are arranged in a simple square array as shown in the figure.l below. Calculate the theoretical fiber volume fraction in the composite lamina. What is the maximum fiber volume fraction that can be arranged in this fashion?                                                             [6]

 

c)         What is the primary function of a fiber surface treatment? Discuss what surface treatment is given to glass fibers, aramid fibers and carbon fibers.

[6]

OR

Q2) a) How are fibers incorporated into a polymer matrix? Discuss in detail how fibers are incorporated into a thermoplastic resin matrix.                                             [6]

b)        Derive the “Rule of mixtures” for an unidirectional fibre composite and solve the following.

PEEK is to be reinforced with 40% by volume of unidirectional carbon fibres and the properties of the individual materials are given below. Calculate the density, modulus and strength of the composite in the fibre direction.                                    [6]

Material

Density

(kg/mQ)

Tensilestrength(GN/m2) Modulus(GN/m2)

PEEK

1300

0.058 3.8

Carbon

1800

2.1 400

fibre

 

c)         List the different types of thermoset and thermoplastic matrices used to make composites. Discuss any one thermoplastic and one thermoset matrix.                         [6]

Q3) a) Discuss how a Differential Scanning Calorimeter (DSC) can be used to find the degree of cure. What is the effect of cure time and cure temperature on the degree of cure and rate of cure.                                                                                                                  [4]

b)        Discuss prepreg lay up process w.r.t. tooling requirement, raw material and basic processing steps and explain the use of vaccum bag and autoclave during prepreg lay up. State the merits and demerits of the process.                                                 [6]

c)        Explain the Darcy’s model for resin flow through fiber network or prepreg lay up. Also explain the Kozeny-Carman equation for determination of permeability. Explain the limitations of Darcy’s model and Kozery-Carman equation.                     [6]

OR

Q4) a) With a typical exothern curve explain the gel-time test to determine the curing characteristics of a resin-catalyst combination.                                                                       [5]

b)        Discuss the features of screw design and barrel design for thermoset injection molding.                                                                                                                               [5]

c)         Compare the tooling requirements for various processes like wet lay up; spray lay up and prepreg lay up.                                                                                                    [6]

Q5) a) What is liquid composite molding process? Explain resintransfer molding w.r.t material, mold, process steps and applications. Compare RTM with compression molding.     [6]

b)        Explain the theory for void formation in autoclave processing. [4]

c)        Discuss four sub models in short to analyze the complete composite processing phenomena.                                                                                                 [6]

OR

Q6) a) What is the significance of studying the kinetic model in autoclave processing?  [4]

b)        Draw a typical pressure and temperature curve during an autoclave process and discuss the purpose of supplying heat 8 applying pressure during the process. Discuss the resin flow submodel when resin flow is normal to the tool plate w.r.t autoclave cure process.                                                                                                                               [8]

c)        Discuss the process of pultrusion. Give its merits and demerits. [4]

SECTION – II

Q7) a) Discuss the thermomechanical model in case of filament winding. [6]

b)        Discuss the winding techniques in filament winding process. Give a few applications of the same.                                                                                                      [6]

c)        Discuss the process parameters that control the fiber wet-out in filament winding.    [6]

OR

Q8) a) What are the reasons for residual stress in laminates? Discuss the stress sub-model in case of a symmetric laminate.                                                                                        [6]

b)        Discuss the process of thermoplastic tape winding w.r.t. material, tooling part making, methods of applying heat and pressure. State the advantages and disadvantages of the same process.                                                                                              [8]

c)         Give a few applications made by tape winding process.                     [4]

Q9) a) What are the advantages of adhesive bonding over mechanical joints.[6]

b)        Discuss the different types of adhesives used with composites. [6]

c)        Discuss the modes of failure in adhesive bonding.                               [4]

OR

QI 0) a) What are the different methods for surface preparation to inprove bond strength in case of composites.                                                                                                          [6]

b)        What are the objectives of machining of composites? Why cutting tools for composite machining coated with diamond or some othersubstance.[4]

c)        Discuss waterjet cutting used for machining composites. What are the process parameters affecting the cutting performance w.r.t. composites. [6]

QII) a) What are polymer nano composites? Classify polymer nano composites on the basic of number of dimensions.                                                                                      [4]

b)        What is intercalation? Explain the different ways to intercalate clay particles.            [6]

c)         What is exfoliation? How does it differ from intercalation? How is exfaliation carried out?                                                                                                               [6]

OR

Q12) a) What are the different steps involved in manufacturing of clay polymer nanocomposites?                                                                                                                               [8]

b)        Write a short note on polymer nano-composites with CNTs in a thermoplastic matrix.                                                                                                                       [4]

c)         Compare polymer nanocomposites with normal composites based on composition, mechanical and thermal properties.                                                        [4]

Leave a Comment