S T R A I N

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Lecture 4
S T R A I N
Objective
In engineering, the deformation of a body is
specified using the concept of normal and shear
strain. In this lecture, we will define these
quantities and show how they can be determined
for various types of problems.
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Normal Strain
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Shear Strain
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Example
The slender rod shown in figure is subjected to
an increase of temperature along its axis, which
creates a normal strain in the rod of ?z
40(10-3)z1/2 , where z is in given meters.
Determine (a) the displacement of the end B of
the rod due to the temperature increase, and (b)
the average normal strain in the rod.
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Solution
Part (a).
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Part (b).
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Example
A force acting on the grip of the lever arm shown
in the figure causes the arm to rotate clockwise
through an angle of ? 0.002 rad. Determine the
average normal strain developed in the wire BC.
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Solution
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Example
The plate is deformed into the dashed shape. If
in this deformed shape horizontal lines on the
plate remain horizontal and do not change their
length, determine (a) the average normal strain
along the side AB, and (b) the average shear
strain in the plate relative to the x and y axes.
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Solution
Part (a).
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Part (b).
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