Dr.A.P.J.Abdul Kalam University
Bachelor of Engineering
Third Semester Main Examination, Dec-2020
Strength of Materials [ME-221]
Branch-ME
Time: 3:00 Hrs Max Marks 70
Note : Attempt any five questions.
All question carry equal marks.
Q.1 (a) Explain the terms strain, Shear strain, young’s modulusand modulus of rigidity.
(b) A tension bar taper from (d+a) diameter to (d-a) diameter Prove that the error
involved in using the mean diameter to calculate the young modulus is (10a/d)^2 percent.
Q.2 (a) A closed coiled helical spring has its free length as 120mmit absorbs 40 N-m of energy when fully
compressed and the coil are in contact. The mean coil diameter is 80mm. Determine the diameter of
steel wire required and number
of coil, if maximum shear stress is to be 120MPa, G=80GPa.
(b) A 280mm*120mm*10mm I beam in to be used as a cantilever of 3.6 m length. Find the uniformly
distributed load which can be carried safety if the permissible stress is 125 MPa.
Q.3 (a) What is the assumption made in the theory of torsion?
(b) Develop an expression for strain energy in a shaft subjected to torsion.
Q.4 (a) What do you mean by Theories of failure? What is their importance
(b) What is meant by equivalent length of columns? What are its values for different end conditions of
column?
Q.5 (a) Derive the equation for principal stress from a given two dimensional stress element
(b) Derive the relation.
Q.6 (a) Deduce an expression for allowable tungsten moment of a thin walled tube. Also find an
approximate Expression
for strength weight ratio of such tube.
(b) Derive the expression of stress and deflection of helical spring of circular wire.
Q.7 (a) Derive Euler’s formula for column with pinned ends.
(b) Briefly explain true stress and true strain.
Q.8 (a) Briefly describe the construction of leaf spring with neat sketch
(b) A shaft transmits 280 KW of power at 160 rpm. Determine The diameter of solid shaft to transmit
the power.
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