Bengal Engineering and Science University 2007 B.E Civil Engineering Experimental analysis of stress & strain - Question Paper

the ques. paper is with the attachment.

FIRST HALF

1. a) What is polarization? Explain briefly various types of polarization.

b)    Classify polariscope.

c)    Write down the Goodier relations for model to prototype transformation for two-dimensional photoelasticity.    (11+2+3)

2.    a) In case of plane polariscope, deduce the expression for the intensity of light finally coming out of the analyzer.

b) For the above case, show how the effect of principal stress direction can be achieved.    (12+4)

3.    a) Explain Maxwells Stress Optic Law.

b)    Express Stress Optic Law in terms of relative retardation, principal stress and also principal strain.

c)    Name two common photoelastic model material.    (4+11+1)

4.    Explain a suitable method of separation of the principal stresses in case of two-dimensional photoelasticity, writing down only the steps.    (16)

5. a) Draw a labeled neat sketch of a circular polariscope, indicating the optical elements used.

b)    What do you understand by Tardys method of fringe compensation.

c)    Write short notes (any TWO):

i)    Temporary Birefringence

ii)    Wave Plate

iii)    Iso-chromatic fringe pattern

iv)    Calibration of photoelastic model material (any method)

6.    a) What are the common types of Strain Gauges used, depending on their principles of operation?

b)    What are the required basic characteristics of Strain Gauges?

c)    With neat labeled sketch explain briefly the principle of operation of the Huggenberger Tensometer.    (4+2+10)

7.    a) Explain briefly the optimum characteristics, which an electrical resistance Strain Gauge should exhibit.

b) What is Strain Sensitivity of the metallic alloy used as conductor for the electrical resistance Strain Gauge? Show that the Gauge Sensitivity depend on the dimension of the conductor and the Specific Resistance of the metallic alloy.

(6+2+8)

8.    a) Explain the terms:

i)    Axial Strain Sensitivity

ii)    Normal Strain Sensityvity

iii)    Gauge Factor

b) Show that the Cross Sensitivity Factor of a flat grid electrical resistance Strain Gauge can be determined from the geometry of the gauge only.    (4+12)

9.    a) What is Strain Rosette? Under what circumstances Strain Rosettes are used.

b) For a three element Rectangular Strain Rosette mounted on a steel specimen, the following data have been recorded :

e_a = 285 micro cm / cm along 0_A = 0 eb = 65 micro cm / cm along 0_B = 45

Ec = 102 micro cm / cm along 0c = 90

Find the Principal Strains, Principal Stresses and Principal angles. Take E for steel as 210 GPa and p. for the steel as 0.3.    (4+12)

10. Write short notes on any TWO of the following providing neat sketches wherever required :

i)    Alloys for Electrical Resistance Strain Gauge

ii)    Weldable Strain Gauge

iii)    Capacitance Gauge

Attachment: bengal-engineering-and-science-university-2007-b-e-civil-engineering-1091-1.pdf

Earning:   Approval pending.