Name of the College : Sphoorthy Engineering College
University : JNTUH
Department : MECHANICAL ENGINEERING
Subject Code/Name : 09A51403/PRINCIPLES OF MACHINE DESIGN
Year : December 2011
Degree : B.Tech
Year/Sem : III/I
Website : sphoorthyengg.com
Document Type : Model Question Paper
Download Model/Sample Question Paper : https://www.pdfquestion.in/uploads/sphoorthyengg.com/4828-09A51403%20-%20PRINCIPLES%20OF%20MACHINE%20DESIGN.pdf
Principles of Machine Design :
B. Tech III Year I Semester Examinations, December-2011
(MECHANICAL ENGINEERING(MECHATRONICS)
Time: 3 hours
Related : Sphoorthy Engineering College 09A51404 Machine Tools B.Tech Question Paper : www.pdfquestion.in/4822.html
Max. Marks: 75
Answer any five questions :
All questions carry equal marks :
1.a) Compare the theories of failure by drawing the boundaries of their application for biaxial stress condition and explain their field of application.
b) A round steel rod is subjected to axial tension of 50 MPa with superimposed torsion of 100 MPa. What is your best prediction of the safety factor with respect to yielding if the material has a tensile strength of 500 MPa? [10+5]
2.a) Draw and explain S-N Curve? What is the difference between S-N Curve for ferrous and non-ferrous components?
b) A rotating bar made of steel 45C8 with ultimate strength of 630 MPa is subjected to a completely reversed bending stress. The corrected endurance limit of the bar is 315 MPa. Draw the S-N curve. Calculate the fatigue strength of the bar for a life of 90,000 cycles. [7+8]
3.a) Find out the inclination of the plane of maximum shear stress in the transverse fillet weld. Also find the expression for the maximum shear stress.
b) Compare the strength of the Transverse and Parallel fillet welds. [12+3]
4. A 75 mm countershaft in a machine shop transmits 39 kW at 315 rev/min. It is made of cold rolled steel with ultimate tensile strength of 490.0 MPa and yield strength of 310 MPa. It is supported on bearings 1.50 m apart. It has two pulleys mounted upon it.
One is 0.45 m in diameter and is located 0.38 m to the right of left hand bearing and it receives power in a horizontal direction from a pulley to its right. The other pulley is 0.635 m in diameter, is located 0.45 m to the left of the right hand bearing and delivers power in a vertical direction to a machine below it.
For kb= 1.75 and ks= 1.25, find the stress in the shaft and compare it with the design stress as obtained from the code. [15]
5.a) Write short notes on (i) Surging of the spring, (ii) Buckling of the compression spring.
b) A load of 5 kN is dropped from a height of 50 mm axially on the spring of a wire of diameter 12 mm, spring index equal to 6 and the number of active coils as 8. Find the stresses induced in the spring. [8+7]
6. Design a flat belt horizontal drive for transmitting 5.8 kW at 1400 rpm of motor. Speed of the driven pulley is 450 rpm and the maximum permissible peripheral speed is 16 m/s.
Assume 3% creep, load factor =1.2, density of the belt material = 980 kg/m3 , modulus of elasticity for the belt material = 100 MPa , Ultimate 1 tensile strength = 25 MPa, centre distance =2.8 m and endurance limit for the belt material = 4 MPa. [15]
7.a) Compare the sliding and rolling contact bearings.
b) A bearing, supporting a power transmitting shaft, is subjected to 3000N radial load and 45000N axial thrust. The shaft rotates at 400r.p.m and the expected life of the bearing is 10,000hours. Select a suitable bearing, if the diameter of the shaft is 40mm. [5+10]
8.a) Explain the importance of Lewis form factor in designing the spur gear. Derive the equation of beam strength of spur gear.
b) In a spur gear drive the diameter of pinion is 80 mm and the centre distance is 160 mm. The power to be transmitted is 4.5 kW at 800 rpm of pinion.
Using 200 full depth teeth and material for pinion steel with permissible static bending stress of 200 MPa and for gear a steel with a permissible static bending stress of 150 MPa, determine the necessary module and width of the teeth. [5+10]