fremderregten

Fremderregten is a term used in German-language physics and engineering to describe phenomena driven or excited by an external source, as opposed to intrinsic or self-sustained processes. The word combines fremd (external or foreign) with erregen (to excite), and it appears in phrases such as fremderregte Schwingungen (externally driven vibrations) or Fremderregung (external excitation).

In mechanical systems, a mass–spring–damper subjected to an external periodic force F(t) exhibits forced vibrations. The steady-state response depends on the driving frequency in relation to the natural frequency and damping. At or near resonance, the amplitude of vibration can become large, highlighting the importance of design to avoid undesired amplification. In electrical engineering, a driven RLC circuit shows a similar forced response, where the input signal imposes the behavior of the circuit rather than the system generating the motion internally. The same concept applies in acoustics and other fields where an external source controls the system’s motion or field.

Fremderregung is distinguished from self-excited or self-oscillating behavior, which relies on internal feedback to sustain motion, often with little or no continuous external input. Instances of fremderregte phenomena include vibration testing, modal analysis, noise and vibration control, and actuator-driven measurements. These techniques use external excitation to characterize system properties such as damping, stiffness, and resonant frequencies.

See also: resonance, forced vibration, damping, eigenfrequency, self-oscillation.