Definition
The condition in which an object or system is driven by an external force at a frequency matching its own natural frequency of vibration, causing the amplitude of oscillation to build up to large levels. In aircraft systems, resonance can occur in mechanical structures, electrical circuits, and acoustic systems, and it is often something engineers design to either exploit or avoid.
Plain English
When something is pushed or shaken at exactly the rate it naturally wants to move, the motion grows much larger. A small, well-timed push produces a big response.
Context Anchor
Seen in aircraft maintenance discussions about vibration, cracked parts, engine operation, propellers, and structural fatigue.
Derivation
From the Latin resonare, meaning 'to sound again' or 'to echo.' The original sense was acoustic — sounds reinforcing each other — and the meaning broadened to any system whose response builds up when driven at its natural frequency.
Why Pilots Care
Uncontrolled resonance can rapidly fatigue metal and cause structural failure or loss of control.
Analogy
Like pushing a child on a swing. If you push in time with the swing's natural rhythm, it goes higher and higher with very little effort. Push at the wrong time and nothing much happens.
Grounding Statement
Resonance is the build-up of vibration when repeated force arrives at just the right timing.
Intuition Check
Resonance does not mean simply “a vibration.” It means a vibration that is being strengthened because the timing matches the object’s own natural vibration rate.
Example Sentence 1
The engineers redesigned the engine mount to shift its natural frequency away from normal operating RPM and avoid resonance.
Example Sentence 2
Engine mounts are designed with dampers to prevent resonance from developing during normal operating RPM ranges.