STUPIDSID
Solve any one question from Q.1(a,b) &Q.2(a,b)
1(a)
Explain the following.
. Factor of safety and service factor.
Preferred series.
Mechanical Advantage.
. Factor of safety and service factor.
Preferred series.
Mechanical Advantage.
6 M
1(b)
Design a key for muff coupling which connect two shaft of 29 mm diameter, transmits 35KW at 1440 rpm. The maximum torque is 25% greater than average torque. Allowable shear stress and crushing stress for key material are = 65 N/mm2 and 160 N/mm2
4 M
2(a)
Classify Keys Also prove that crushing stress in key material is twice the shear stress.
4 M
2(b)
Draw neat sketch Cotter joint. Write design steps and state their applications.
6 M
Solve any one question from Q.3(a,b) &Q.4(a,b)
3(a)
A lin shaft rotating at 200 rpm is to be transmitted 20KW. The shaft is made of M.S. With allowable shear stress 42Mpa. Determine the diameter of shaft.
4 M
3(b)
A forged steel made with 40 C8 of 50 mm diameter is subjected to completely reversed bending stress of 300 N/mm2. Determine the life of bar. Use following data:
Sut = 600N/mm2
Surface Finish Factor = 0.43
Size Factor = 0.85
Reliability factor 0.897 at 90% reliability.
Factor of safety
= 1.5
Notch sensitivity = 0.8
Theoretical stress concentration = 2.6
Sut = 600N/mm2
Surface Finish Factor = 0.43
Size Factor = 0.85
Reliability factor 0.897 at 90% reliability.
Factor of safety
= 1.5
Notch sensitivity = 0.8
Theoretical stress concentration = 2.6
6 M
4(a)
A cantilever of beam made of cold drawn steel 40C8 with Sut = 600 N/mm2 and Syt 380 N/mm2 The maximum and minimum force at free end varies from -50N to + 150 N. Reliability factor is 0.897, surface finish factor and size factor are 0.77 and 0.85 respectively. Notch sensitivity at fillet is 0.9 and theoretical stress concentration factor is 1.44. If factor of safety is 2 determine diameter of beam according to Goodman's criteria. Assume effective length of beam 100 mm.
6 M
4(b)
Explain Design of shaft based on Tensional Rigidity.
4 M
Solve any one question from Q.5(a,b) &Q.6(a,b)
5(a)
Explain with neat sketch Differential screw.
4 M
5(b)
A Power screw having double start threads nominal diameter 25 mm and pitch 5mm subjected to axial load of 1000N. The outer and inner diameter of the screw coller is 50 and 20 mm respectively. The coefficient of friction for collar thread and screw thread are 0.15 & 0.20 respectively. The screw rotates at 12 rpm. Assume uniform wear condition, and allowable bearing pressure is 5.77 N/mm2. Determine,
i) Power required to rotate the screw.
ii) Stresses in screw Body & threads.
iii) No.of threads of nut in engage with screw.
i) Power required to rotate the screw.
ii) Stresses in screw Body & threads.
iii) No.of threads of nut in engage with screw.
12 M
6(a)
Following data refers to C-Clamp.
Maximum clamping force = 4000N.
Screw type - Single start trapezoidal threaded
Nominal Diameter = 12 mm.
Pitch = 2mm.
Coefficient of collar friction = 0.25.
Coefficient of screw friction = 0.12.
Mean collar Diameter = 12mm.
Operator force at the end of handle = 80N.
Distance between the aixs of handle and surface of nut in clamped condition = 150mm.
Nut height = 25mm.
Determine,
i) Length of handle if 50 mm additional length for gripping.
ii) Stressess in screw body at two critical sections.
Bearing Pressure on screw thread.
Maximum clamping force = 4000N.
Screw type - Single start trapezoidal threaded
Nominal Diameter = 12 mm.
Pitch = 2mm.
Coefficient of collar friction = 0.25.
Coefficient of screw friction = 0.12.
Mean collar Diameter = 12mm.
Operator force at the end of handle = 80N.
Distance between the aixs of handle and surface of nut in clamped condition = 150mm.
Nut height = 25mm.
Determine,
i) Length of handle if 50 mm additional length for gripping.
ii) Stressess in screw body at two critical sections.
Bearing Pressure on screw thread.
13 M
6(b)
Explain self locking and overhauling of power screw.
3 M
Solve any one question from Q.7(a,b) & Q.8(a,b)
7(a)
Explain with neat sketch any two types of screw fastenings.
6 M
7(b)
Acylindrical head is connected to a flange by bolts, The inside is 1.5N/mm2 if bolt have permissible shear strength of 80 N/mm2 Determine the size of bolt neglection initial tightening. If for the same application. M30 bolts are used, find number of bolts required.
12 M
8(a)
Write advantages of welded joints over thread joints. Also prove that stress acting on thorat is equal to force on weld upon 0.707hl where h=leg size of weld and 1= length of filtet weld.
6 M
8(b)
A welded bracket is shown in figure 1 below, carries of load of 60 KN. Calculate size of weld if shear stress in weld is 100 N/mm2
!mage
!mage
12 M
Solve any one question from Q.9(a,b) & Q.10(a,b)
9(a)
Draw a neat labled sketch of Laminated leaf spring. Stage functions of any two components.
5 M
9(b)
Following data is given for helical compression spring.
Axial load = 8000N.
Spring rate = 72 N/mm.
Mean coil diameter = 125 mm.
Tensile strength of spring material = 550 Mpa.
Modulus of rigidity = 80000 Mpa.
Permisssible shear stress for spring wire is half the tensile strength of spring material.
Standard Spring Wire diameter = 18, 19, 20, 21, 22, 23, 24, 25, 27, 29, 30 mm
Determine
i) Wire diameter
ii) No. Of active coils.
Axial load = 8000N.
Spring rate = 72 N/mm.
Mean coil diameter = 125 mm.
Tensile strength of spring material = 550 Mpa.
Modulus of rigidity = 80000 Mpa.
Permisssible shear stress for spring wire is half the tensile strength of spring material.
Standard Spring Wire diameter = 18, 19, 20, 21, 22, 23, 24, 25, 27, 29, 30 mm
Determine
i) Wire diameter
ii) No. Of active coils.
11 M
10(a)
Explain the following terms.
i) Wahl's factor.
ii) Active and Inactive coils.
i) Wahl's factor.
ii) Active and Inactive coils.
4 M
10(b)
A composite compression spring has two closed coil. Outer spring is of 15mm longer than inner spring. The outer spring has 10 coils of mean diamter 36 mm & wire diameter 30 mm & wire diameter 5 mm. When spring is subjetcted to an axial load 1000N, Modulus of rigidity may be taken as 81370 N/mm2. Find.
i) Compression of each spring
ii) Load shared by each spring.
iii) Shear stress induced in each spring.
i) Compression of each spring
ii) Load shared by each spring.
iii) Shear stress induced in each spring.
12 M
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