6. Dynamic behavior of the crankshaft

So far, we've studied engine acyclism "at source", i.e. as cyclic variations in instantaneous torque. Of course, the acyclism "perceived" at the crankshaft is a function of the total rotary inertia of the mobile coupling (crankshaft + flywheel + clutch). More than torque variations, it's this resulting acyclism that we're interested in, whether we're talking in terms of angular displacement, angular velocity or angular acceleration, because it's these quantities that the design office will "manipulate" to optimize flywheel inertia, for example, and that the testing department will be able to measure.