ABSTRACT
A mechanical circuit consists (Section 4.1) of masses, dampers, and springs, and is analogous to an electrical circuit consisting (Section 4.3) of inductors, resistors, and capacitors. A mechanical (electrical) circuit is characterized by the impedance (Section 4.2), which is the ratio of the mechanical (electromotive) force to the velocity (electric current). The impedance is generally complex (Section 4.4), since it appears as a coefficient of proportionality between two quantities that may have different amplitudes and phases (Section 4.5). Several circuits, electrical or mechanical, may be associated in series, in parallel (Section 4.6) or in hybrid arrangements (Section 4.9), and the total impedance is specified by the partial impedances of each separate element. The calculation of impedances of complex circuits (Section 4.7) is an application of the algebra of complex numbers, and the laws of association are different (Section 4.8) for mechanical and electrical circuits. The mechanical circuits are used in the suspensions of vehicles (e.g., cars, trains, etc.) and in the “soft” or “shock absorbing” mountings of machinery; the electrical circuits are used in a variety of electrical devices, for example, radios, computers, appliances, and so on. The electromechanical circuits also have applications like control systems, actuators, and so on.
