|Quoting RoseFlyer (Reply 1):|
It's pretty much impossible to know what the frequency is for an airliner. It's not a single degree of freedom so the square root of K/M doesn't work. Certain components do have problems with resonance though. It can cause wear on specific components.
When the resonance is fed by aero loads it is known as flutter. It can cause significant components, such as wings and control surfaces, to break off in next to no time.
For this reason, a lot of work is putting into finding out just which frequencies and vibration modes the airframe has. This is done analytically, through calculations and complex computer models, and empirically through mounting an entire aircraft on elastic mounts, adding accelerometers all over the airframe and exciting the aircraft at various frequencies.
While it has never been my primary area of work I've been involved and I've had some fun hours putting the accelerometers and associated wiring in place...
|Quoting RoseFlyer (Reply 5):|
There aren't models out there for a whole plane that I've heard of,
Now you have heard of them.
They're simplified, of course, but detailed enough to accurately predict the major (read: dangerous) resonant modes and frequencies.
It can also be a PITA with components. I've been through having the weight saving from a component replacement being consumed - and then some - by the structures people adding reinforcements to get the replacement components inherent frequency responce out of a known vibration frequency in the aircraft.
I thought I was doing good trying to avoid those airport hotels... and look at me now.