ME2303 DESIGN OF MACHINE ELEMENTS ANNA UNIVERSITY PREVIOUS YEAR QUESTION PAPER NOVEMBER/DECEMBER 2010
Posted by R.Anirudhan
B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2010
ME 2303 — DESIGN OF MACHINE ELEMENTS
(Common to Automobile Engineering)
Time :Three hours Maximum : 100 Marks
(Design data book may be permitted)
Answer ALL questions
PART A — (10 × 2 = 20 Marks)1. What are the factors that govern selection of materials while designing a machine component?
2. Write Soderberg equation for a machine component subjected to
(a) Combination of mean and variable torques
(b) Combination of mean and variable bending moments.
3. What do you mean by stiffness and rigidity with reference to shafts?
4. Suggest suitable couplings for
(a) Shaft with parallel misalignment
(b) Shafts with angular misalignment of 10°
(c) Shafts in perfect alignment.
5. State three conditions where tap bolts are used.
6. What are the reasons of replacing riveted joint by welded joint in modern
7. What is the effect of increase in wire dia on the allowable stress value?
8. What type of stresses is produced in a disc flywheel?
9. For a journal bearing the maximum operating temperature must be less than
10. Why is piston end of a connecting rod kept smaller than the crank pin end?
PART B — (5 × 16 = 80 Marks)
11. (a) A simply supported beam has concentrated load at the centre which fluctuates a value from P to 4P. The span of the beam is 500 mm and its cross section is circular with a diameter of 60 mm. Beam material is cold drawn 0.2% carbon steel. Calculate the maximum permissible value of P for a factor of safety of 1.3. Beam surface is ground.
(b) A medium force fit on a 50 mm shaft requires a hole tolerance of 0.025 mm and a shaft tolerance of 0.016 mm. The maximum interference is to be 0.042 mm. How will you dimension the hole and the shaft, if hole deviation is H?
12. (a) A transmission shaft is supported on two bearings which are 1m apart. Power is supplied to the shaft by means of a flexible coupling, which is located to the left of left hand bearing. Power is transmitted from the shaft by means of a belt pulley, 250 mm diameter, which is located at a distance of 300 mm from the left hand bearing. The mass of the pulley is 20 kg and the ratio of belt tension on tight and slack sides is 2:1. The belt tensions act vertically downward. The shaft is made of steel with yield stress 300N/mm2 and the factor of safety is 3. Determine the shaft diameter, if it transmits 10 kW power at 360 rpm from the coupling to the pulley.
Or(b) Design a rigid type of flange coupling to connect two shafts. The input shaft transmits 37.5 kW power at 180 rpm to the output shaft through the coupling. The service factor for the application is 1.5. Select suitable material for various parts of the coupling.
13. (a) A steel plate subjected to a force of 5 kN and fixed to a channel by means of three identical bolts is shown in Fig. 1. The bolts are made from plain carbon steel 45C8 and the factor of safety is 3. Specify the size of bolts. Figure 1
Or(b) A bracket carrying a load of 20 kN is to be welded as shown in Figure 2. Calculate the size of the weld if the working shear stress is not to exceed
70 N/mm2. Figure 2
14. (a) Design a close-coiled helical spring of silicon-manganese steel for the valve of an IC engine capable of exerting a net force of 65N when the valve is open and 54N when the valve is closed. The internal and external diameters are governed by space limitations, as it has to fit over bushing of 19 mm outside diameter and go inside a space of 38 mm diameter. The valve lift is 6 mm.
(b) Design and draw suitable flywheel for a four stroke four cylinder 133 kW engine running at 375 rpm. Due to space restriction the flywheel diameter should not exceed 1.2m
15. (a) A single row deep groove ball bearing No.6002 is subjected to an axial thrust load of 1000N and a radial load of 2200N. Find the expected life that 50% of the bearings will complete under this condition.
(b) The connecting rod of a petrol engine is to be designed for the following data.
Piston diameter 80 mm
Stroke 120 mm
Weight of the reciprocating parts 15N
Length of connecting rod 240 mm
Max speed 2800 rpm.
Explosion pressure corresponding to 10° of crank angle is 3 MPa.
Factor of safety 6
If the connecting rod is to be made of 40Cr1 Steel, find the dimensions of
the I-section connecting rod.