Answer the
following questions
(A) A hollow circular
bar of outside diameter twice the inside
diameter is used as a beam. The
bar is subjected to bending moment of 40 kN m. If the allowable bending stress
in the beam is to be limited to 100 MN/m 2 ,
find the inside
diameter of the bar.
(B)Make a list of
six principal theories of failure. Explain major consideration and
application of maximum principal stress theory.
(C)A flat bar 32 mm wide and 12
mm thick is loaded by a steady tensile load of 85 kN. The
material is mild steel with yield point stress of 315 N/ mm^{2 }.Find the factor
of safety based on the yield point.
(D)Design the longitudinal joint for a 125 m diameter steam boiler carrying a steam pressure of 5 N / mm‘. The allowable stress of the plate material is 80 N / mm 2 in tension. Length of the shell of boiler is 5 m. Take allowable stress for shielded arc weld = 95 N / mm 2 .
(E) Find the length of belt (open and cross) necessary to drive a pulley of 80 cm diameter running parallel at a distance of 12 m from the driving pulley of diameter 480 cm.
(F)Make a list of various types of gear trains. Derive an expression for ve1ocity ratio of a simple gear train.
(G)A uniform disc of diameter 30 cm and weighing 5 N is mounted on one end of an arm of length 60 cm. The other end of the arm is free to rotate in a universal bearing. If the disc rotates about the arm with a speed of 300 r.p.m. clockwise, looking from the front, with wb.at speed will it precess about the vertical axis ?
(H) For what type of materials ultrasonic machining (USM) is best suitable process of material removal ? Make a sketch showing major parts of USM setup.
(I) Classify comparators. Explain the working and constructional details of any one comparator.
JOB 
Immediate Predecessors 
Duration 
(days) 
Mean 
STD. deviation 

A 


10 
2 
B 
 
5 
1 
C 
A 
16 
2 
D 
A 
12 
2 
E 
B,C 
15 
1 
(i) Draw the
project network in activity on arc mode.
(II) Under PERT assumptions, determine the distribution of project duration.
SECTION A
Attempt at least one question
(A) A short column of Isection 25 cm x 20 cm has crosssection Sea of 52 cm^{2} and maximum radius of gyration 107 cm. A vertical load in kN acts through the centroid of the section together with a parallel load of in /4 kN acting through a point on the centreline of the web distant 6 cm from the centroid. Calculate the greatest allowable value of in if the maximum stress is not to exceed 65 MN/ m 2. What is then the minimum stress ?
(B) A closecoiled helical
spring is to have a
stiffness of 900 N/m in
compression, with a maximum
load of 45 N and a maximum shearing
stress of 120 N / mm ^{2}. The solid length of the spring
(i.e., coils touching) is 45
mm. Find the
(I) wire diameter;
(II) mean coil radius;
(III) number of coils.
Take modulus of rigidity of material of the spring = 0 4 x 10 ^{5} N / mm 2.
(C) A simple band brake. is applied to a drum of 560 mm diameter which rotates at 240 r.p.m. Angie of contact of the band is 270‘. One end of the band is fastened to a Fix pin and the other end to the brake lever 140 mm from the fixed pin. The brake lever is 800 mm long and is placed perpendicular to the diameter that bisects the angle of contact. Assuming the coefficient of friction as 0 3, determine the necessary pull at the end of the lever to stop the drum if 40 kW of power is being absorbed. Also, find the width of the band if its thickness is 3 mm and the maximum tensile strength is limited to 40 N /mm^{2.}
3. (A) A Vbelt of 60 cm 2 crosssection has a groove angle of 40° and an angle of lap of 150°, ยต= 0 10. The mass of the belt per meter run is 12 kg. The maximum allowable stress in the belt is 850 N /cm 2 . Calculate the horse power that can be transmitted at a belt speed of 30 m/s.
(B) Derive an expression for maximum and minimum values of swaying couple.
(C) A Vtwin engine has the cylinder axis at right angles and the connecting rods operate a common crank. The reciprocating mass per cylinder is 15 kg and the crank radius 75 mm. The length of the connecting rod is 0 3 m. Show that the engine may be balanced for primary forces by means of a revolving balance mass. If the engine speed is 500 r.p.m., what is the value of the maximum resultant ,secondary force ?
SECTION—B
Attempt at least one question
4.(A) Design the rectangular key for a shaft of 50.mm diameter. The shearing and crushing stresses for the key material are 42 MPa and 70 MPa, take w = 16 mm and t = 10 mm, where in = width and t = thickness of the key.
(B) Design a cast iron protective type flange coupling to transmit 15 kW at 900 r.p.m. from an electric motor to a compressor. The service factor may be assumed as 1. 35. The following permissible stresses may be used :
Shear stress for shaft, bolt and key material = 40 MPa
Crushing stress for bolt and key = 80 MPa
Shear stress for cast iron = 8 MPa
(C) The following data relate to a shaft held in long bearings :
Length of the shaft =1.2 m
Diameter of the shaft = 14 mm
Mass of a rotor at midpoint = 16kg
Eccentricity of centre of mass of rotor from centre of rotor = 0.4 mm
Modulus of elasticity of the shaft material = 200 GN / m^{2 }
Permissible stress in the shaft material = 70 x 10^{6} N / m^{2}
Determine the critical speed of the shaft.
5(A) A steel rod is turned with a singlepoint cutting tool having rake angle 10°. The chip thickness was measured as 15 mm. The dynamometer gave indication of cutting forces as 980 N for tangential component and 440 N for thrust component, compute friction force at chip tool interface and shear strength of the material (assume uncut chip thickness as 06 mm and uncut width of chip as 18 mm).
(B) During straight turning of 25 mm diameter steel bar at 300 r.p.m. with HSS tool, a tool life of 10 minutes was obtained. When the same bar was turned at 250 r.p.m., the tool life increased to 525 minutes. What will be the tool life at a speed of 275 r.p.m?
(C) Comment
on the following statements related to electrochemical machining (ECM) ;
(i)
"ECM is reverse of electroplating."
(II)
"AC power supply cannot be used in ECM."
(III)
"Tool wear in ECM does not involve material loss."
(iv)
"ECM is a hi^ly predictive process of material removal."
(D) Write any five differences between traditional and nontraditional machining processes.
Section—C
Attempt
at least one question
6.
(A) A company uses the purchased item continuously in the manufacturing of a
large number of products. The item has the following characteristics :
Demand/year
= 8000 Pc
Purchase
price = f 100/Pc
Safely
stock = 1 • 6 x lead time demand
Lead
time from order to delivery = 4 weeks
Purchasing
quantity = 1000 Pc
Inventory
carrying cost/year = 20% of the item value
A
reorder point system that continuously reviews stock on hand is used to
generate purchase orders. The product is produced and in demand in all 52 weeks
of the year :
(I)
Determine the reorder point, the average tiedup capital in inbound stock, the
inventory turnover rate in the stock, the average runout time in the stock and
the annual inventory carrying cost for the item.
(II)
As the company buys several items from the same supplier it is considering
changing its review principle from continuous review to periodic review stock
on hand of all purchased items every second week. By doing this, it is thought
that it will be possible to coordinate deliveries of several items from this
supplier. How will the answer in (i) change if a switch is made to periodic
review?
(B) A company makes two types of leather belts, A and B. Belt A is high quality belt and belt B is of lower quality. The respective profits are f 4 and f 3 per belt. Each belt of type A requires twice as much time as belt of type B, and if all the belts were of type B, the company could make 1000 per day. The supply of leather is sufficient for only 800 belts per day (both A and B combined). Belt A requires a fancy buckle and only 400 per day are available.
There are only 700 buckles a day available for belt B. What should be the daily production of each type of belt? Formulate as a linear programming problem (solution not required).
(C) The following table shows the jobs of a network along with their time estimates (in days) :
(i) Draw
network diagram.
(ii) Find critical path. Also, find the expected
duration of the project.
(Hi) Calculate the standard deviation of the project
length.
7.
(A) Calculate the fundamental deviation and tolerances and hence the limits of
size for the shaft and hole for the following fit :
60
mm H_{7}f_{8}
The
diameter steps are 50 mm and 80 mm.
(B)
A television repairman finds that the time spent on his jobs has an exponential
distribution with a mean of 30 minutes. If he repairs sets in the order in
which they came in, and if the arrival of sets follows a Poisson's distribution
approximately with an average rate of 10 per 8hour day, what is the
repairman's expected idle time each day? How many jobs are ahead of the average
set just brought in?
(C) A cantilever member 01 m long having crosssection of 005 mxO25 m supports a load of 27.5 kN. What is the maximum shear stress and where does it occur?
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