联系我们： 手动添加方式: 微信>添加朋友>企业微信联系人>13262280223 或者 QQ: 1483266981

H7102
THE UNIVERSITY OF SUSSEX
BEng (Year 2) AND MEng (Year 2) EXAMINATION
January 2021 (A1)
PRINCIPLES AND APPLICATIONS OF STRENGTH OF
MATERIALS
Candidates must attempt 3 questions. Full working of each solution must be shown
Duration: 3 hours
If all four questions are attempted, all will be marked, but the lowest mark will not be
counted in the total for the paper.
Write your answers on A4 paper, scan and save as a single PDF file and upload to
Canvas PDF file name: candidate number_module title
Read Academic Integrity Statement
You are reminded that, unless you have been authorised to do so in School or specific
assessment guidance, you should not access online materials, notes etc. during this examination
or discuss this assessment with others before the end of its 24 hour window. By submitting this
assessment you confirm that you have read the above Statement and are responsible for
understanding and complying with our academic misconduct regulations (found on Student Hub
and here: Academic Misconduct regulations).
H7102 Principles and Applications of Strength of Materials

2
Q1. A spherical tank of diameter 1.0 m contains compressed air at pressure p. The tank
is constructed of two hemispheres joined by a welded seam (see figure Q1).
(a) What is the maximum value of the pressure in the tank if the tensile load f
(Newtons per meter of length of weld) carried by the weld is 0.55 × 106 N/m
[8 marks]
(b) Calculate the thickness of the wall if the maximum direct strain in the wall
should not exceed 3.87×10-4
.
[7 marks]
(c) What is the maximum shear stress max in the wall of the tank
[5 marks]
(For steel, assume elastic modulus E = 210 GPa, and Poisson’s ratio = 0.29)
Figure Q1
Turn over
H7102 Principles and Applications of Strength of Materials

3
Q2. A steel rod is subjected to tension by a force P. A right-angle triangular element
ABC is chosen, such that face along the hypotenuse AB is perpendicular to the axis
of the rod, as seen in Figure Q2, for which x = 40 N/mm2
, y = 62.5 N/mm2
and xy
unknown. The cross section area of the rod is A = 314 mm2
.
a) Calculate the normal stress on the face AB.
[6 marks]
b) What is the shear stress on faces BC and AC of the element
[5 marks]
c) Find the value of force P.
[3 marks]
d) For the value of force P found at part c) and assuming circular cross section, find
the diameter of the bar such that the maximum shear stress inside the rod does not
exceed 65 MPa.
[6 marks]
Figure Q2
x

y
xy yx A
C
B
P P
x
y

H7102 Principles and Applications of Strength of Materials

4
Q3. A steel shaft is to be manufactured either as a solid circular bar (of diameter d) or as
a circular tube (of internal diameter di and external do) as defined in Figure Q3. The
thickness of the hollow shaft is to be 10 percent of the outer diameter. The shaft is
required to transmit a torque of 1200 Nm without exceeding an allowable shear
stress of 40 MPa and an allowable angle of twist per unit length of 0.75 o
/m. The
elastic shear modulus of the steel is 78 GPa.
a) Calculate the required diameter d of the solid shaft.
[8 marks]
b) Calculate the outer diameter of the hollow shaft.
[5 marks]
c) What is the ratio of the weights of the two shafts, if they have the same length
[2 marks]
d) Determine the maximum/minimum direct stresses in the solid shaft. At what angle
relative to the axis of the shaft do they occur
[5 marks]
Figure Q3
Turn over
d di do
H7102 Principles and Applications of Strength of Materials

5
Q4. Each girder of the bridge seen in figure Q4 has a length of 50 m and is made of steel
plates welded to form a beam with I cross section. The design of the girders is done
for a uniformly – distributed load of 18 kN/m on each girder. Each girder is simply
supported at ends and has the cross section dimensions seen in the detail drawing
(dimensions in m).
a) Derive an equation for the axial moment of inertia (about axis z passing through
the mass centre of the cross section area) of the cross section of the girder in terms
of the thickness of the web, t.
[3 marks]
b) Calculate the maximum bending stress in one girder.
[7 marks]
c) Calculate the maximum deflection of one girder under the uniformly – distributed
load if the elastic modulus of steel is 210 GPa.
[6 marks]
d) If the maximum allowable shear stress in the beams is 15MPa, find the thickness t
of the web such that the allowable shear stress in the beam is not exceeded.
The maximum shear stress in the web of an I-beam is:
max

8
V
It
bh2
bh1
2
th1
2
[4 marks]
H7102 Principles and Applications of Strength of Materials

6
Figure Q4
End of paper
b=0.6
t=0.03
z h=1.8 h =1.7 1