Campbell Diagram Terminology
Glossary of terms for Campbell diagrams — crossings, engine order lines, frequency curves and resonance speed.
Frequency curve
A plot of a natural frequency against rotational speed, showing the centrifugal stiffening effect.
Engine order line
A straight line through the origin on the Campbell diagram with slope equal to the engine order number, representing the excitation frequency at each speed.
Crossing
A point where a frequency curve intersects an engine order line, indicating a resonance at that speed.
Resonance speed
The rotational speed at which a crossing occurs — the speed at which the excitation frequency equals the natural frequency.