ANNA UNIVERSITY QUESTION PAPER

B.E. AERONAUTICAL ENGINEERING, VI SEMESTER

AE345 EXPERIMENTAL STRESS ANALYSIS

TIME – 3 Hours            MAXIMUM : 100 Marks

PART  A                     (10  X 2 = 20 Marks)ANSWER  ALL QUESTIONS 1.  Distinguish between accuracy  and sensitivity.2.  What is nu ll balancing wheat stone bridge circuit?3.  Based on Principal of operation, classify the extension meters.4.  What are the master grating and model grating o f mor ie technique. 5.  What are the requirement  in selectio n o f Photo elastic materials?6.  How will  you obtain dark and light field  in a circular po lar iscope? 7.  Enumerate the  various Non-Destructive Testing (NDT) methods ?8.  What is a stress gauge?9.  In  what  way  three  dimensio nal  photo  elasticity  is different  from  two-dimensio nalphoto elasticity?10.  Briefly explain Acoustic emission Inspection.

                                                                         PART B                      (5 X 16 = 80 Marks) 

11.  Der ive  an expression for change  in output voltage of wheat stone bridge circuit interms of the changes in resistances.                   16

12a.  Explain in detail the working principle and measurement of strains from anAcoustical  strain gauge with  neat sketch.                           16

                                                    ( OR )

  b.  Der ive  an expressio n for output voltage o f whetstone bridge circuit  for strain gauges.Calculate the sensitivity when  all the gauges are active.  Given Rg = 120 ohms,  Ig = 50 mA, Sg = 2.                16 What are strain rosettes? What ar e their uses? For a rectangular rosette on a steelspecimen eA = -600 x 10-6 , eB = 300 x 10-6, eC = 400 x 10-6. Determine the principalstrains, principal stresses and directio ns Esteel = 210 Gpa.            16

                                                    ( OR )

  b.  Explain with necessary equations how isoclinics are eliminated in circularpolariscope setup. What are the properties of isochromatics?            16

14a.  i.  Explain Fringe sharpening.                    8  ii.  Explain Fringe mu ltiplication technique used in Photoelasticity.           8

                                                    ( OR )  b.  Explain any two compensation techniques used in Photoelasticity.            16

15a.  i.  Why do we require separatio n? Explain any two-separation techniques indetail.                           8  ii.  Explain in detail how stress-freezing technique  is employed in three-dimensio nal Photoelasticity?                    8                                                    ( OR )  b.  Explain  i.  Ultrasonic testing in NDT and their applicatio ns.             8  ii.  Radiography                       8