The stiffer everything is, the more resistant to flutter.
Happily, people in our group are probably not involved in altering the stiffness of aircraft structure. However, were someone to be, I would caution that that statement might be oversimplified. When we consider a wing with two spars, which might flex, and be susceptible to flutter, it could become much more so if one of the spars were stiffened. Were it to be a single spar wing, with a spar well aft in the wing, stiffening could be bad, there is history with this. I do not present myself as expert at this, though I sure am paying attention during some phases of flight testing!
On several of my projects, I have experienced aerodynamic vibration which was the result of vortex shedding off a boom. I have developed aerodynamic fixes for these, necessary for certification.
This was one such project, King Air C90 wingtip pod:
chrisN 27-Feb-13 01:12 #08 Flutter and vibration are not the same thing.##
A really nice explanation of this phenomenon. Worth bearing in mind that where structural vibration is concerned, what matters is the degree of coincidence between the natural frequency (2PiF=SqRoot of the controlling stiffness constraining the part involved, divided by the mass participating on the vibration 'mode') - and the exciting frequency.
So changing the mass or the stiffness will only increase or decrease the natural frequency of vibration of the structure, not eliminate it. This can be good or bad, depends on whether the change takes it closer to the 'exciting' frequency or not. In aeroelasticity, the airflow effectively becomes the spring device - storing energy from the vibrating airfoil.
Vibration can be reduced in amplitude by increasing the damping - the amount of energy in the vibration that is diverted into e.g heat energy, though this also tends to broaden the frequency range over which the natural frequency is at work.
Be in no doubt that real flutter of control surfaces can develop into catastrophic failure very quickly indeed . . . think Brrrp - - - gone
