ANNA UNIVERSITY, B.E. Aeronautical Engineering, VI SEMESTER,
Experimental Stress Analysis
PART A (10 X 2 = 20 Marks)
ANSWER ALL QUESTIONS
1. Distinguish between accuracy and sensitivity.
2. What is null balancing wheat stone bridge circuit?
3. Based on Principal of operation, classify the extension meters.
4. What are the master grating and model grating of morie technique.
5. What are the requirement in selection of Photo elastic materials?
6. How will you obtain dark and light field in a circular polariscope?
7. Enumerate the various Non-Destructive Testing (NDT) methods ?
8. What is a stress gauge?
9. In what way three dimensional photo elasticity is different from two-dimensional photo elasticity?
10. Briefly explain Acoustic emission Inspection.
PART B (5 X 16 = 80 Marks)
11. Derive an expression for change in output voltage of wheat stone bridge circuit in terms of the changes in resistances.
12a. Explain in detail the working principle and measurement of strains from an Acoustical strain gauge with neat sketch.
( OR )
b. Derive an expression for output voltage of whetstone bridge circuit for strain gauges. Calculate the sensitivity when all the gauges are active.
Given Rg = 120 ohms, Ig = 50 mA, Sg = 2.
13a. What are strain rosettes? What are their uses? For a rectangular rosette on a steel specimen ?A = -600 x 10-6 , ?B = 300 x 10-6, ?C = 400 x 10-6. Determine the principal strains, principal stresses and directions Esteel = 210 Gpa.
( OR )
b. Explain with necessary equations how isoclinics are eliminated in circular polariscope setup. What are the properties of isochromatics?
14a. i. Explain Fringe sharpening.
ii. Explain Fringe multiplication technique used in Photoelasticity.
( OR )
b. Explain any two compensation techniques used in Photoelasticity.
15a.i. Why do we require separation? Explain any two-separation techniques in detail. ii. Explain in detail how stress-freezing technique is employed in three-dimensional Photoelasticity?
( OR )
i. Ultrasonic testing in NDT and their applications.