Unformatted text preview: 3.5 and the connecting
rod is designed for bucking about X-axis. The design
will always be satisfactory for buckling about Y-axis.
The most suitable section for the connecting
rod is I-section with the proportions as shown in
Fig. 32.13 (a).
Let thickness of the flange and web of the
section = t
Width of the section, B = 4 t
and depth or height of the section,
H = 5t
From Fig. 32.13 (a), we find that area of the section, Fig. 32.13. I-section of connecting rod. A = 2 (4 t × t) + 3 t × t = 11 t2
Moment of inertia of the section about X-axis, 1
Ixx = 12 4 t (5t ) − 3t (3t ) = 12 t and moment of inertia of the section about Y-axis, 1
1 131 4
(3t ) t 3 =
t × (4 t ) 3 +
Iyy = 2 ×
12 ∴ I xx 419 12
I yy I xx
lies between 3 and 3.5, therefore, I-section chosen is quite satisfactory.
After deciding the proportions for I-section of the connecting rod, its dimensions are determined
by considering the buckling of the rod about X-axis (assuming both ends hinged) and applying the
Rankine’s formula. We know that buckling load,...
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- Spring '11
- Combustion, Internal combustion engine, pistons, Connecting rod, Engine technology, piston pin