Wednesday, October 29, 2008

strength of materials basic mechanical questions

1.Define stress and strain. Write down the S.I. and M.K.S. units
of stress and strain.
2. Explain clearly the different types of stresses and strains.
3. Define the terms: Elasticity, elasticlimit, Young'smodulusandModulus of rigidity.
4. State Hooke's law.
5. Three sections of a bar are having different lengths and different
Diameters. The bar is subjected to an axial load p. Determine the total change
in length of the bar. Take Young's'modul of different sections same.
6. Distinguish between the following, giving due explanation:
(1) Stress and strain,
(2) Force and stress, and
(3) Tensile stress and compressive stress.
7. Prove that the total extension of a uniformly tapering rod of
Diameters D1 and D2, whenthe rod issubjectedto an axial load P is given by 4PL dL .Ceded
Where L=Total length of the rod
8. Define a composite bar. How will you find the stresses and load Carried by each member of a composite bar?
9, Define modular ratio, thermal stresses, thermal strains and Poisson’s ratio.
10. A rod whose ends are fixed to rigid supports, is heated so that
Rise in temperature is rc. Prove that the thermal strain and stresses
Setup in the rod are given by, Thermal strain=a. T and Thermal stress=a.T.E.
Where a=Co-efficient of linear expansion.
11. What is the procedure of finding thermal stresses in a composite Bar?
12 what do you mean by 'a bar of uniform strength’?
13 Find an expression for the total elongation of a bar due to its Own weight, when the bar is fixed at its upper end and hanging freely at the lower end.
14 Find an expression for the total elongation of a uniformly
Tapering rectangular bar when it is subjected to an axial load P.
15.Define and explain the following terms:
Shear force, bending moment, shear force diagram and bending
Moment diagram.
16.What are the different types of beams? Differentiate between
a cantilever and a simply supported beam.
17.What are the different types of loads acting on a beam?
18.Differentiate between a point load and a uniformly distributed load.
19.What are the. Sign conventions for shear force and bending
Moment in general? '
20.Draw the S.F. and, B.M. diagrams for a cantilever of length L
Carrying a point load W at the free end.
21.Draw the S.F. and B.M. diagrams for a cantilever of length L
Carrying uniformly distributed load of w per m length over its entire length.
22.Draw the S.F. and, B.M. diagrams for a cantilever of length L
Carrying a gradually varying load from zero at the free end to w per unit
Length at the fixed end.
23.Draw the S.F. and B.M. diagrams for a simply supported beam
of length L carrying a point loads Wat its middle point.
24.Draw the S.F. and B.M. diagrams for a simply supported beam
Carrying a uniformly distributed load of w per unit length over the entire
Span. Also calculate the maximum B.M.
25.Draw the S.F. and B.M. diagrams for a simply supported beam
Carrying a uniformly varying load from zero at each end to w per unit length
at the centre. '
26.What do you mean by point of contra flexure? Is the point of
Contra flexure and point of inflexion different?
27. How many points of contra flexure you will have for simply
Supported beam overhanging at one end only?
28.How will you draw the S.F. and B.M. diagrams for a beam?
29.Which is subjected to inclined loads?
30.What do you mean by thrust diagram?
31.Draw the S.F. and B.M.diagramsfor a simply supported beam of length L which is subjected to a clockwise couple 11at the centre of the Beam.
32.Define the terms: bending stress in a beam. neutral axis and
section modulus.
33.What do you mean by 'simple bending' or 'pure bending’?
34.What are the assumptions made in the theory of simple bending?
35.Derive an expression for bending stress at a layer in a beam.
36.What do you understand by neutral axis and ", moment of
Resistance?
37.Prove the relation,
M=L=~
I y R'
l=M.O.I.
where M=Bending moment,
y=Distance from N.A.
f=Bending stress,
R=Radius of curvature.
E=Young's modulus, and
(Bangalore University, Jan. 1990)
38.What do you mean by section modulus? Find an expression
for section modulus for a rectangular, circular and hollow circular sections.
39.How would you find the bending stress in unsymmetrical
section?
40.What is the meaning of 'Strength of a section’?
41.Define and explain the terms: modular ratio, fletched beams
and equivalent section.
42.What is the procedure of finding bending stresses in case of
fletched beams when it is of (i) a symmetrical section and (ii) an
unsymmetrical section?
43.Explain the terms: Neutral axis, section modulus, and moment
of resistance. (Bangalore University, July 1988)
44.Show that for a beam subjected to pure bending, neutral axis
coincides with the centroid of the cross-section.
(Bangalore University, March 1989)
45.Prove that the bending stress in any fiber is proportional to the distance
of that fiber from neutrally in beam. (BhavnagarUniversity, 1992)
46.Define the terms: Torsion, torsion rigidity and polar moment
of inertia.
47.Derive an expression for the shear stress produced in a circular
shaft which is subject to torsion. What are the assumptions made in the
derivation?
48.Find an expression for the torque transmitted by a hollow
Circular shaft of external diameter=Do and internal diameter=Dj.
49.Define the term 'Polar modulus'. Find the expressions for polar
Modulus for a solid shaft and for a hollow shaft
50.What do you mean by 'strength of a shaft' 1
51.Define torsional rigidity of a shaft. Prove that the torsional
rigidity is the torque required to produce a twist of one radian in a unit
length of the shaft.
52.Find an expression for strain energy stored in a body which due
to torsion or Prove that the strain energy stored in a body due to torsion is given
By, 2 U=.Lxv. 4C
where q=Shear stress on the surface of the shaft,
C=Modulus of rigidity, and
V=Volume of the body.
53.A hollow shaft of external diameter D and internal diameter d
is subjected to torsion, prove that the strain energy stored is given by,2
U=~ (D2+cf) xV4CD
where V=Volume of the hollow shaft and
q=Shear stress on the surface of the shaft.
54.What is a spring? Name the two important types of spring.

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