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November 2011

What are the properties to be considered in selecting the materials in the design of machineparts? Discuss.Classify the various types machine design. A hot rolled steel shaft is subjected to a torsional moment that varies from 330 N.m clockwise to110 N.m counter clockwise and an applied bending moment at a critical section varies from440N-m to-220 N-m. The shaft is of uniform cross-section and no key way is present at the critical

section. Determine the required shaft diameter. The material has an ultimate strength of 550MN/m2 and yield strength of 410MN/m2.Take the endurance limit as half the ultimate strength,factor of safety of 2, size factor of 0.85 and surface finish factor of 0.62.

November 2011

Discuss fatigue and endurance limit.Explain the following methods of reducing stress concentration:(i) Drilled holes.(ii) Using large fillet radius.

 A double riveted lap joint is made between 15mm thick plates. The rivet diameter and pitch are25mm and 75mm respectively. If the ultimate stresses are 400MPa intension, 320 MPa in shear and 640 MPa in crushing, find the minimum force per pitch which will rupture the joint. If theabove joint is subjected to a load such that the factor of safety is two, find out the actual stressesdeveloped in the plates and the rivets.

November 2011Define the following terms related to screw fastenings:(i) Stress area(ii) Major diameter (iii) Minor diameter. A punching press is required to punch a maximum hole size of 20mm diameter in a material

having ultimate shear strength of 300N/mm2. If the thickness of the sheet is 5mm design thescrew and the nut.

November 2011

Describe the purpose of gib in cotter joint. What are the applications of cotter joints?Design a knuckle joint to transmit 140KN, with permissible stresses in tension; shear andcompression are 75MPa; 60MPa and 150MPa respectively.

November 2011

Explain about various types of stresses acting on a rotating shaft.Explain the effect of key way on the strength of a shaft.

November 2011

Describe with the help of neat sketches, the types of various shaft couplings, mentioning the usesof each type.

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November 2011

What is the procedure adopted in the design of machine elements?How do you classify materials for engineering use?Explain stress concentration in detail and various methods to reduce stress concentration inmachine members.

November 2011

Explain various types of theories of failure.Explain the soderberg method for combination of stress. A stepped shaft has maximum diameter 45mm and minimum diameter 30mm. The fillet radiusis 6mm. If the shaft is subjected to an axial load of 10KN, find the maximum stress inducedtaking stress concentration in account.

November 2011

Design a triple rivetted lap joint, to join two plates of 6mm thick. The permissible stresses are

= 80 MP a , =100 MP a and T=60 MP a . Calculate the rivet diameter, rivet pitch and distancebetween the rows of rivets. Use zig-zag riveting. Draw a neat sketch of joint.

November 2011

Enumerate various stresses due to intial tightening of screwed fartmers.The cylinder head of effective diameter 300mm for a steam engine is subjected to 1.2 MPa. It isheld in position by means of 12 studs. A soft copper gasket is used to make joint leak proof.

November 2011

Determine the size of blots or studs, so that the stress should not exceed 100 MPa.Discuss the function of coupling. Give at least three practical applications.

November 2011

Differentiate between a cotler and a key.Explain the reasons for preferring hollow shafts over solid shafts.Explain the details of shaft design based on:

(i) Torsional rigidity.(ii) Lateral rigidity.

November 2011

Design and draw a muff coupling to transmit 50HP at 120 rpm. The shaft and key are made of the same material having allowable shear stress of 30N/mm2 and compressor stress of 80N/mm2.The flange is made, as cast iron with allowable shear stress is 15N/mm2.

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November 2011What are the manufacturing considerations to be considered by design?State the advantages and drawbacks of cast-iron as an engineering material.Briefly explain shear stress and shear strain.Calculate the diameter of solid shaft to transmit 50KW at 180rpm. If the angle of twist in a lengthof 4 meters is not to exceed 0.4°. The allowable stress in the material is 70MP a and modulus of rigidity is 84 GPa.

November 2011

Discuss the factors affecting endurance limit.Determine the diameter of a circular rod made of ductile material with a fatigue strength(complete reversal),=265 MPa and tensile yield strength of 350 MPa. The member issubjected to a varying axil load from= -300KN to= 700KN and has a stressconcentration factor is 1.8. Use factor of safety as z.

November 2011

Explain the following terms in connection with riveted joints:(i) Pitch(ii) Back pitch(iii) Diagnal pitch (iv) Margin.What do you understand by the term riveted joint? Explain the necessity of such a joint.

November 2011

List out the advantages and disadvantages of screw joints. A mild steel cover plate is to be designed for an inspection hole in the shell of a pressure vessel.The hole is 120mm in diameter and the pressure inside the vessel is 6N/mm2.Design the cover plate along with the bolts. Assume the allowable tensile stress for mild steel on 60 MP a and for bolt material as 40 MP a .

November 2011

Describe the design procedure of sleeve & cotler joint.Design a cotler joint with two gibs to transmit an axial force of 130KN. The permissible stressesare 165 MP a in tension; 100MP a in shear and 180MP a in crushing.

November 2011Differentiate between torsional rigidity design and lateral rigidity design of shafts.What are the causes of failure of shaft?Design a bushed pin type flexible coupling for connecting two shafts when HP to be transmittedis 50; speed of the shaft 100rpm; diameter of the shaft 50mm. The bearing pressure in therubber bush and allowable stress in the pins are to be limited to 0.45N/mm 2 respectively. Sketchthe coupling.

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