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4 SHEAR. CALCULATIONS FOR CUT
AND CRUSHING

4.1. The concept of pure shear

Shear is called such a kind of deformation when in cross-
sections of the rod there is one internal force factor - shear force
Q .
Shear deformation can be obtained in the case when on the
beam acting two equal forces that are close enough to one another
and perpendicular to the axis of the beam and directed in opposite
directions (fig.4.1 a).

а) b)

Figure 4.1

Using the method of sections it is easily determined that
Q  P.
We will remind the integral relationship between shear force
and tangential stresses  (fig. 4.1 b)

Q    dF .
F
Considering that the tangential stresses divided by the cross
section area F evenly, we obtain

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