# PTU B.Tech Mechanical Engineering 6th Semester May 2019 71267 EXPERIMENTAL STRESS ANALYSIS Question Papers

PTU Punjab Technical University B-Tech May 2019 Question Papers 6th Semester Mechanical Engineering (MECH)

Roll No.
Total No. of Pages : 02
Total No. of Questions : 09
B.Tech.(ME) (E-I 2011 Onwards) (Sem.?6)
EXPERIMENTAL STRESS ANALYSIS
Subject Code : DE/ME-3.5
M.Code : 71267
Time : 3 Hrs. Max. Marks : 60
INSTRUCTION TO CANDIDATES :
1.
SECTION-A is COMPULSORY consisting of TEN questions carrying T WO marks
each.
2.
SECTION-B contains FIVE questions carrying FIVE marks each and students
has to attempt any FOUR questions.
3.
SECTION-C contains T HREE questions carrying T EN marks each and students
has to attempt any T WO questions.

SECTION-A
1.
Write briefly :

a) What are principal planes? State their significance.

b) Classify the strain gauges on the basis of gauge construction.

c) State the factors affecting the gauge relation.

d) Describe the use of compensation techniques in two dimensional photoelasticity.

e) List the properties which an ideal photoelastic material should exhibit.

f) State Neuman's strain optic relationship.

g) How atomospheric parameters affect the performance of brittle coatings?

h) Define sensitivity of birefringence coating.

i) State gauge relation and the factors affecting it.

j) What do you understand by fringe multiplication? What is its effect in

photoelasticity?
1 | M - 7 1 2 6 7

( S 2 ) - 1 6 1 5

SECTION-B
2.
Describe the potentiometer circuit and its application to strain measurement.
3.
Describe the arrangement of optical elements in a circular polariscope along with a neat
sketch. Also, state the four different arrangements for circular polariscope and
recommend these arrangements for dark field and light field arrangements.
4.
Describe the stress freezing method for three dimensional photoelasticity.
5.
Describe gauge sensitivities and gauge factor. What are transverse strain effects in
electric resistance strain gauges? How are the corrections for these effects achieved?
6.
Describe the birefringence coating with application, methodology and parameters
affecting the birefringence coatings.

SECTION-C
7.
Describe the method of brittle coating and its calibration. Describe the brittle coating
crack patterns with the help of sketches for the following cases of principal stress :

a) 1= 2 > 0, 3 = 0

b) 1 > 0, 2 < 0, 3 = 0

c) 1 > 2 > 0, 3 = 0
8.
The strain components at a point in a three-dimensional steel component subjected to
arbitrary loadings are given as: state of stress at a point are xx = 240, yy = 320, zz = 0,
xy = 140, yz = 640, zx = 90. Determine the corresponding stress components and
principal stress. Consider Young's modulus of elasticity = 210 GPa and shear modulus =
78 GPa.
9.
Write short notes on the following :

a) Stress transformation

b) Birefringence coatings

c) Stress separation in photoelasticity

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