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00000ME401121901

State and explain the theories of failure (a) Rankine theory (b) von Mises theory

and (c) Maximum shear stress theory. Plot the region of safety for each theory.

Explain Soderberg, Goodman and Gerber’s criteria for design under fatigue

loading.

A steel shaft subjected to a torque that varies over a range of +40%. Determine
the diameter of the shaft if it transmits 15 kW at 250 rpm. The material has an
ultimate strength of 600 MPa and yield strength of 400 MPa. Take FoS 3.

PART 8

Answer any two full questions, each carries 15 marks.
What is the difference between lead and pitch? Write the relation connecting

them.
Explain the stresses acting on a Screw fastener.

A cylinder head is fastened to the cylinder of a compressor using 6 bolts of M20
size. Bolt material is C20 steel. The maximum fluid pressure is 3.5 MPa, and
the cylinder diameter is 75 mm. A soft gasket is used. Assume the initial tension

required in each bolt as 40 kN. Determine the factor of safety.

What do you mean by the efficiency of a power screw? How do you find the

efficiency of a self-locking screw?
What are the different types of threads used in power screw?

The square thread of a screw jack 80 x 72 x 16 (in mm), with a double start is to
raise a load of 100 KN. The mean collar diameter is 130 mm. The coefficient of
friction for the threads and the collar are 0.1 and 0.2 respectively. Determine

a. The torque required to raise the load.

b. The efficiency of the screw.

c. Whether self-locking exists?

Explain the failures modes of riveted joints and how will you determine the

efficiency of a rivet joint?

Design a double riveted butt joint with equal widths of cover plates to join two

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