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and the maximum bending stress, due to inertia of the connecting rod,
Z = Section molulus.
From above we see that the maximum bending moment varies as the square of speed, therefore,
the bending stress due to high speed will be dangerous. It may be noted that the maximum axial force
and the maximum bending stress do not occur simultaneously. In an I.C. engine, the maximum gas
load occurs close to top dead centre whereas the maximum bending stress occurs when the crank
angle θ = 65° to 70° from top dead centre. The pressure of gas falls suddenly as the piston moves from
dead centre. Thus the general practice is to design a connecting rod by assuming the force in the
connecting rod (FC) equal to the maximum force due to pressure (FL), neglecting piston inertia
effects and then checked for bending stress due to inertia force (i.e. whipping stress).
= 2× 3. Force due to friction of piston rings and of the piston
The frictional force ( F ) of the piston ri...
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- Spring '11