Mechanical Engineering Answers

 Sketch stress-strain curve of a ductile materials. Show different points and respective

strength in the curve. Also discuss the curves briefly.

What is the significance of the study of 'Mechanics of Material'? Explain briefly. And Why knife has ultra thin sharp edge? Explain from the view point Of solid mechanics.

A quantity of gas occupies a volume of 0.4M² a pressure of 100KN/M³ and a temperature of 20°C the gas is compressed isothermally to a pressure of 450KN/M² then expanded adiabatically to its intial volume for this quantity of gas determine;

1:the heat transferred during the compression

2:the change of internal energy during the expansion

3:the mass of gas.

Steam at 1.4MN/M² and of dryness fraction 0.7 is throttled to 0.11MN/M², determine the dryness fraction of the steam after throttling

.A cam with minimum radius of 40 mm, rotating clockwise at a uniform speed is to be designed to

give a roller follower at the end of a valve rod, the motions as given below: 1.To rise the valve through

60 mm during120° rotation of the cam; 2.To keep the valve fully raised through next 30°; 3.To lower

the valve during the next 60°; and 4.To keep the valve closed during the rest of the revolution. The

diameter of the roller is 20 mm and diameter of the cam shaft is 25 mm.The displacement of the

follower has to take place with simple harmonic motion. Draw the profile of the when the line of stroke

is along the axis of the cam shaft.

A symmetrical tangent cam operating a roller follower has the following particulars: Radius of the

base circle of cam = 40 mm, roller radius = 20 mm, angle of ascent= 75o

, total lift = 20 mm, speed of

the cam shaft = 300 rpm. Determine: 1.the principle dimensions of the cam; 2.acceleration of the

follower at the beginning of the lift; and 3. acceleration of the follower where straight flank merges

into a circular nose.

.From the following data draw the profile of a cam in which the follower moves with simple harmonic motion (SHM) during

ascent while it moves with uniformly accelerated and decelerated motion during descent.

least radius of cam = 50 mm.,

angle of ascent = 48o

angle of dwell b/w ascent & descent= 48o

angle of descent = 60o

lift of follower = 40 mm.

diameter of roller= 30 mm

If the cam rotates at 360 r.p.m anti-clockwise, find the maximum velocity & acceleration of the follower

during descent. The follower axis passes through the axis of cam shaft.

.A cam is to be designed for a knife edge follower with the following data:

1. Cam lift = 60 mm during 90° of cam rotation with simple harmonic motion.

2. Dwell for the next 30°.

3. During the next 60° of cam rotation, the follower returns to its original position with simple harmonic motion.

4. Dwell during the remaining 180°.Draw the profile of the cam when the line of stroke is

offset 20 mm from the axis of the cam shaft. The radius of the base circle of the cam is 50 mm. Determine the maximum velocity and acceleration of the follower during its ascent and descent, if the cam rotates at 250 r.p.m.

In a four bar chain ABCD, link AD is fixed and the crank AB rotates at 10 rad/sec clockwise. Length of the links are AB=60

mm; BC=CD=70 mm; DA= 120 mm. When the angle DAB = 60o and both B and C lie on the same side of AD, find 1.angular

velocities (magnitude and direction) of BC and CD; and 2.angular acceleration of BC and CD.