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GUJARAT TECHNOLOGICAL UNIVERSITY
DIPLOMA ENGINEERING – SEMESTER – V• EXAMINATION – SUMMER 2016
Subject Code: 3351902 Date:11/05/2016
Subject Name: Design of Machine Element
Time: 02:30 PM to 05:00 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 out factor that effects selection of materials.
2. Define 1) Ductility 2) Elasticity.
3. Explain factor of safety and write it’s equation.
4. Sketch double riveted butt joint.
5. List application of knuckle joints.
6. State type of stresses.
7. State fundamental equation of pure bending with meaning of each terms.
8. Define solid length and free length of tension spring.
9. List advantages of antifriction bearing.
10. List out machine elements subjected to eccentric loading.
Q.2 (a) Explain factors effecting the value of F.O.S. 03
OR
(a) Determine the force required to cut 60 mm diameter blank from 5 mm thick plate. Τu=350 n/mm^2. 03
(b) Determine rivet diameter to join 12 mm thick plates by single riveted lap joint. The pitch of the joint 70 mm .Also determines tearing, shearing and crushing efficiency of joint. Take [T]=60 N/mm^2, [6c]= 100 N/mm^2 and [6t]= 80 N/mm^2. 03
OR
(b) Find knuckle rod diameter and pin diameter considering failure for joining to connect two m.s. rods of equal diameter subjected to axial tensile load of 15 kN. Take [T] =60 N/mm^2, [6c]= 150 N/mm^2 and [6t]= 80 N/mm^2. 03
(c) Determine the standard sizes of 6 round bars having smallest diameter of 10mm and largest diameter of 32 mm . 04
OR
(c) Enlist types of design and explain. 04
(d) State application, advantages and limitations of power screw. 04
OR
(d) A simple screw jack having square thread has 50 mm mean diameter and pitch of 12.4 mm. If the coefficient of friction between screw and nut is 0.13 .Determine the torque on the screw to lift the load of 25 kN. Find the efficiency of the screw assuming that the load rotates along with the screw. 04
Q.3 (a) Explain types of levers based on number of fulcrums. 03
OR
(a) State types and applications of leaf springs. 03
(b) A bell crank lever is to be designed to lift the load of 10 kN. Acting at the end of short arm of the lever. The length of short arm is 500mm and long arm is 750 mm. allowable shear stress and tensile stress for lever and pin materials are 60 Mpa and 80 Mpa respectively. Allowable bearing pressure for pin is 8 Mpa. Determine pin dimension. For pin L/d=1.25 03
OR
(b) Write design procedure of semi elliptical spring with main and graduated leaves. 03
(c) A solid shaft is subjected to bending moment of 3.46 kN.m and torque of 11.5 kN.m. The shaft material has ultimate tensile stress 690 Mpa. and ultimate shear stress 516 Mpa. Determine shaft diameter if F.S. =6(consider equivalent torque only) 04
OR
(c) State the design steps of sleeve/Muff coupling. 04
(d) Two 100 mm. diameter shafts are connected by flange coupling having 250 mm pitch circle diameter for the bolts .six bolts are used for coupling. for shaft and key [τ]=65 Mpa. for C.I. flange [τ]=7.5 Mpa and for bolts [τ]=30 Mpa. Determine, 1) power transmitted 2) diameter of bolt. Take speed 400 rpm and key way effect .(take key way effect factor 1.3) 04
OR
(d) A valve spring having inner diameter of coil as 40 mm, deflects for 40 mm. at the maximum axial load of 500 N. Determine the wire diameter and number of turns . Allowable shear stress for spring is 300 Mpa. , spring index =6 and modulus of rigidity, G= 0.82x10^5 N/mm^2. 04
Q.4 (a) Define eccentric loading & List the machine elements subjected to eccentric loading. 03
OR
(a) State types of coupling and application of couplings. 03
(b) 20 kN load is acting at the end of the ‘C’ clamp having a rectangular cross section. The eccentric distance is 150 mm. in horizontal direction. Find the dimensions of rect. Section if permissible stress is 100 N/mm^2 for clamp. Take h=2b 04
OR
(b) A spindle of a drilling machine is subjected to a maximum load of 10 kN during operation. Determine the diameter of the solid cast iron column if the tensile stress is limited to 40 Mpa. Eccentric distance is 400mm. 04
(c) Calculate spigot and socket dimensions (only diameter and do not consider bending) of a socket and spigot type cotter joint to connect two similar rod subjected to axial load of 75 kN. In both direction. The safe stresses are 50 Mpa in tension, 40 Mpa in shear and 100 Mpa in crushing. 07
Q.5 (a) State application and classification of pressure vessels 04
(b) A cylinder with 150 mm inside diameter and 15 mm plate thickness is subjected to internal pressure of 5 N/mm^2. Determine hoop stress ,longitudinal stress and maximum shear stress in the cylinder 04
(c) Write difference between antifriction and journal bearing. 03
(d) The basic load rating for the selected bearing is 50 kN. If the expected bearing life is 6000 Hrs. calculate the permissible equivalent load for the bearing at 500 rpm.(Take k=3) 03
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