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Unformatted text preview: ins. The perpendicular (or transverse)
components produces bending action (also called whipping action) and the stress induced in the
connecting rod is called whipping stress.
It may be noted that the perpendicular components will be maximum, when the crank and
connecting rod are at right angles to each other.
The variation of the inertia force on the connecting rod is linear and is like a simply supported
beam of variable loading as shown in Fig. 32.11 (b) and (c). Assuming that the connecting rod is of
uniform cross-section and has mass m1 kg per unit length, therefore,
Inertia force per unit length at the crankpin
= m1 × ω2 r
and inertia force per unit length at the piston pin
Inertia force due to small element of length dx at a distance x from the piston pin P,
dF1 = m1 × ω2r ×
∴ Resultant inertia force,
m1 × ω2 r x 2 FI = m1 × ω r × × dx = l
l l 0
= 1 × ω2 r = × ω2 r
...(Substituting m1 · l = m)
This resultant inertia force acts at a distance of 2l / 3 from the piston pin P.
Since it has been assumed that rd mass of the connecting rod is concentrated at piston pin P
(i.e. small end of connecting rod) and rd at the crankpi...
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- Spring '11