2. Dynamic impedance and transfer functions

2.1 Impedance representation

This observation of linearity has a considerable benefit: it allows us to represent the vibratory response of any solid subject to vibratory excitation using an impedantial formulation; This formulation expresses the relationship between forces (and moments) and vibratory displacements (or velocities, or accelerations) from an "input" section (notion of source) to an "output" section (notion of receiver) linked to each other by a "transfer path", using "transfer matrices" that are independent of amplitude (and therefore dependent only on frequency) between sources, transfer paths and receivers.

The sources are usually machines transforming energy (electrical, thermal, hydraulic or pneumatic) into mechanical work (circular or reciprocating...