What is the special name for resonance in a rotating shaft?

The special name for resonance in a rotating shaft is referred to as critical speed. Critical speed is the speed at which a rotating shaft experiences resonance, leading to maximum vibration amplitude. This occurs when the frequency of the shaft's rotational speed matches its natural frequency.

Understanding critical speed is crucial in vibration analysis because, while operating at or near this speed, the system can suffer from excessive vibrations, which may cause mechanical failure or damage. It's important for engineers and technicians to calculate and avoid operating at these speeds. When the shaft spins at its critical speed, even small imbalances can lead to significant dynamic responses, potentially resulting in catastrophic failure.

The other terms mentioned have different meanings in vibration analysis. Vibrational excitation refers to the force applied to an object that causes it to vibrate but is not specifically tied to resonance in a rotating shaft. Natural frequency is related to the inherent frequencies at which a system tends to oscillate in the absence of external forces, but it doesn't capture the specific resonance phenomena in rotating machinery like critical speed does. Eigenvalue is a mathematical concept that relates to the characteristics of a system, particularly in structural dynamics and systems analysis, but is not commonly used to describe resonance in rotating shafts.