Mechanical Measurement and Metrology - Jan 2014

Mechanical Engineering (Semester 4)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) Define metre in terms of wavelength standards. List the advantages of wavelength standards over material standards.(6 marks) 1 (b) Describe with a neat sketch:
(i) Imperial standard yard
(ii) Wringing phenomena of slip gauges(8 marks) 1 (c) Four length bars of basic length 100 mm are to be calibrated using a calibrated length bar of 400 mm whose actual length is 399.9992 mm. It was also found that length of bars B, C and D in comparison to A are +0.0002 mm, +0.0004 mm and -0.0001 mm respectively and the length of all the four bars put together in comparison to standard calibrated bar is +0.0003 mm longer. Determine the actual dimensions of all the four end bars.(6 marks) 2 (a) Differentiate between:
(i) Hole basis and shaft basis system of tolerances
(ii) Interchangeability and selective assembly(8 marks) 2 (b) Write notes on:
(i) Compound tolerances
(ii) Gauge tolerance.(4 marks) 2 (c) Determine the dimensions of hole and shaft for a fit 30H₈f₇. The given data are: i=0.45D^1/3 + 0.001D, IT8=25i, IT7=16i. Fundamental derivation of shaft 'f' is -5.5D^0.41 30 mm diameter lies in the diameter step of 18-30 mm. sketch the fit and comment on the same.(8 marks) 3 (a) Explain with a neat sketch, the working of Solex pneumatic gauge.(8 marks) 3 (b) Explain with a neat sketch, the construction and working of LVDT.(8 marks) 3 (c) Show the arrangement of a angle gauge, with a neat sketch by selecting minimum number of guages for the angles 30°15'33" and 54°63'42"(4 marks) 4 (a) What is the best size wire? Derive an expression for the same in terms of the pitch and angle of the thread.(6 marks) 4 (b) Explain 3-wire method of measuring effective diameter of screw thread.(8 marks) 4 (c) Explain the principle of interferometry. Write a note on optical flat.(6 marks) 5 (a) With a neat block diagram, explain the generalized measurement system with an example to each stage.(8 marks) 5 (b) Distinguish between:
(i) Primary and secondary transducer
(B) Active and passive transducer(6 marks) 5 (c) Define the following terms with reference to measurement system:
(i) Calibration
(ii) Sensitivity
(iii) Hysteresis
(iv) Threshold value(6 marks) 6 (a) With a neat sketch, explain the working principle of a CRO(8 marks) 6 (b) State the advantages of electrical signal conditioning elements(6 marks) 6 (c) Explain with a neat sketch, Ballast circuit diagram.(6 marks) 7 (a) With a neat sketch, describe the Pirani gauge used for pressure measurement(8 marks) 7 (b) With a neat sketch, explain the working principle of proving ring.(6 marks) 7 (c) Explain with a suitable diagram, the working of hydraulic dynamometer.(6 marks) 8 (a) Sketch ans explain the working principle of optical pyrometer(8 marks) 8 (b) Describe the step to be taken for the preparation of specimen and mounting of strain gauges.(6 marks) 8 (c) What is a thermocouple? State the laws of thermocouple.(6 marks)