Modeling an elbow and associated moving parts
Torsional rotor dynamics - Distribution of inertia and stiffness

The average equivalent moment of inertia of the connecting rod and piston is calculated as I_eq (kg.m²), assuming that the connections are free of play and the parts are dimensionally stable. In the usual way, this average moment of inertia is represented by a concentrated mass M_e (kg) placed on the crankpin axis at a distance R (m) from the crankshaft axis. We have :I_eq = M_e R²

From the parameters defined in figure 28, the expression for the kinetic energy of the connecting rod and piston is written :$E_{\text{c}}=\frac{1}{2}I\left(\alpha ,\phi \right)$