Andhra University BE/B.Tech Mechanical Engineering Design of Machine Elements-I Previous Paper 2012
1.(a) State the major stresses developed in a helical spring.
(b)Give the object of machine design.
(c) what tapper is usually given to cotters ? what is meant by draw of cotter ?
(d) How a key way affects the stress induced in a shaft ?
(e) Sketch Laminated spring with full nomenclature ?
(f) Name different modes of failure ?
(g) Define welding and give its users ?
2 Design a typical rigid flang couple for connecting a motor and a centrifugal pump shafts .The coupling needs to transmit 15KW at 1000RPM.The allowable shear stress of the safety key and volt materials are 60mpa;50mpa and 25mpa respecteively.The shear modules of the shaft material may be taken as 84gpa.the angle of twist of the shaft should be linked to one degree in 20 times the shaft diameter .Also sketch the coupling.
3(a)Sketch and explain difference types of welded joints.
(b) Determine the diameter of the circular rod made of ductile material with a fatigue stress(couple stress reversal) σe=265MPa and tensile yield strength of 350MPa. The member is subjected varying axil load form -300 X 103 N to 700 X 103 N and has a stress concentration factor of 1.8 .use factor of safety as 2.0
4(a) Explain nipping and short peening
(b)A stream engine cylinder of size 0.3m X 0.4m operates at 1.5MN/m2 pressure .the cylinder head is connected by means of 8volts having yield point stress of 350 MN/m2 and endurance limit of 240 MN/m2.The volts are tightened with an initial load of 1.5 times the stream load .the join is made leak proof using soft copper gasket which renders the effect of external load to be of .determine the size of the volt if factor of safety is 2.Assume stress concentration factor as 3.
5(a)Explain stress concentration and methods of reducing it
(b)a circular column made up of carbon steel having an ultimate strength of 44 kN/cm2 is have a length of 2.7m and is to support an eccentric load of 72kNa at a distance of 7.5cm from a center line factor of safety is 2.2. find the outside diameter of the column if the column is hallow and inner diameter is 0.8 times outside diameter.
6(a)explain the mechanism of fatigue failure.
(b)design suitable diameter for a circular shaft required to transmit 90kw at 180rpm.The shear stress in the shaft is not to exceed 700MPa and the maximum torque exceed the mean by 40.Also find the angle of twist in the length of 2m.Take g=90GPa.
7(a)Define load, Stress and Strain. Discuss the various types of stresses and strains.
(b)Explain clearly about static failure theories.
8(a)Write notes on different design models, welding inspection and spring materials.
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