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GUJARAT TECHNOLOGICAL UNIVERSITY
DIPLOMA ENGINEERING – SEMESTER – V • EXAMINATION – WINTER- 2016
Subject Code: 3351902 Date: 21- 11- 2016
Subject Name: Design of Machine Elements
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make Suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Use of programmable & Communication aids are strictly prohibited.
5. Use of only simple calculator is permitted in Mathematics.
6. English version is authentic.
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Q.1 Answer any seven out of ten. 14
1. List of factor affecting the value of Factor of Safety.
2. State the advantages of standardization.
3. Write the value of progression ratio for R5, R10, R20 and R40 series.
4. What is stress concentration?
5. Enlist the different types of Keys.
6. State the assumptions made in the design of thin cylinder.
7. Write the basic equation of bending theory, showing notations used.
8. Define Machine design and list out different types of design.
9. If the value of induced hoop stress and longitudinal stress on thin cylindrical shell are 100 MPa and 50 MPa respectively then find value of maximum shear stress.
10. If SKF bearing No. 6006 is a deep groove ball bearing then what is size of bore?
Q.2 (a) Differentiate between V-thread and square thread. 03
OR
(a) State the application of power screw. 03
(b) Compare cotter joint with knuckle joint in respect of (i) Use (ii) Type of loading and (iii) Construction. 03
OR
(b) Draw the neat sketch of double cover, double riveted butt joint with zigzag pattern. (Two views). 03
(c) In a double riveted butt joint with two equal cover strips, having zigzag arrangement of riveting the thickness of the plate 9 mm. Consider allowable tensile , crushing and shear stress are 100 MPa, 150 MPa and 80 MPa respectively. Calculate :- i) diameter of rivet and ii) pitch of rivet joint. 04
OR
(c) Two mild steel bars are connected together with knuckle joint to resist axial load of 200KN. Calculate the diameter of steel bar and the diameter of knuckle pin if the safe stresses for bar and pin are [σt] = 100 MPa and [τ] = 80 MPa.04
(d) A cotter joint is used to connect two rods of equal diameter. The axial load to be resisted 100 KN. The working stress is 70 MPa in tension, shear stress is 0.8[σt] and in crushing it is 2[σt]. Find (i) diameter of rod end and (ii) diameter of spigot end (iii) thickness of cotter. 04
OR
(d) The compressive load on a screw jack is 50 KN. Safe compressive stress in screw = 100 MPa, pitch of the single start square thread = 8 mm and allowable bearing pressure = 16 MPa. Find:- (i) Size of the screw and (ii) height of nut. 04
Q.3 (a) State the application of leaf spring and materials of leaf spring used for automobiles. 03
OR
(a) Draw neat sketch of exhaust valve lever and label its parts. 03
(b) What is eccentric loading? Give at least four names of machine elements subjected to eccentric loading. 03
OR
(b) State importance of preloading. 03
(c) Write the equations bending stresses induces and deflection occurring in the leaf spring having full length leaves and graduated leaves, in semi elliptical leaf spring., 04
OR
(c) Design a fulcrum pin of a bell crank lever to lift a load of 2250 N acting at the end of 125 mm long arm. The effort is applied at the end 04 of 150 mm long arm. Allowable shear stress and bearing pressure for pin are 70 MPa and 10 MPa respectively. Take L/D = 1.25 for pin.
(d) The spindle of a drilling machine is subjected to a maximum load of 10 KN during operation. The distance between the axis of the spindle and the axis of the column is 400 mm. Determine the maximum and minimum stress induced in the drilling column if the diameter of solid C.I column is 102 mm. 04
OR
(d) Explain the design procedure of foundation bolts of pillar crane. 04
Q.4 (a) Differentiate between shaft, axle and spindle. 03
OR
(a) Explain the design procedure of key. 03
(b) A closed coiled helical spring is to be designed for loads ranging from 2.5 KN to 3.0 KN. The axial compression of spring for load range is 10 mm, mean diameter of coil is 36 mm and spring index is 6. Calculate : (i) diameter of spring and (ii) No. Of active coils and (iii) spring stiffness. Take G= 0.8 x 105MPa. 04
OR
(b) Determine thickness and outer diameter of hydraulic cylinder press whose internal diameter is 300 mm. The maximum water pressure is 20 MPa and allowable hoop stress for C.I cylinder is 40 MPa. Use lami’s equation. 04
(c) A C.I flanged coupling is transmitting 11 KW at 500 RPM permissible shear stress for the shaft and bolt material is 60 MPa and 40MPa respectively, permissible crushing stress for the both is 100 MPa and permissible shear stress for hub material is 6 MPa. Design for 25 % overload capacity. Determine the (i) shaft diameter , (ii) diameter of Hub, (iii) No. Of bolts, and (iv) bolt diameter. Take necessary assumptions. 07
Q.5 (a) Standardise six size of shaft diameter between 10 mm to 32 mm. 04
(b) What is pressure vessel? List the materials used for pressure vessel and classify pressure vessel. 04
(c) Sketch an antifriction bearing and lable its different elements. 03
(d) Differentiate between journal bearing and anti-friction bearing. 03
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