Duration of turbulence is not a factor, intensity is!
All modern airplanes have been designed with a flexible structure ready to take punishing weather and vibrate with the impact of the shock wave to dissipate the energy of turbulence.
They have been designed to vibrate longitudinally along the fuselage and rotationally to take in the torque induced by wing shock. The wings are designed to flex and vibrate to behave in a ductile mode.
Even the empennage, the end of the fuselage including the rudder and elevators, is designed to twist and shake safely.
However the pilot during an intense turbulence or even in the absence of it can subject the plane to stresses above the safe levels, do maneuvers that are not safe for that weather and cause damage to structure.
Fatigue which is the first culprit to look into happens mostly by the routine stresses of flight and engine vibration and has to be checked at routine service intervals.
FAA crash reports are a good source to start researching about effect of bad weather on flights, planes, and pilots' decision making.
I did some search on Youtube and found this on flutter of the airplanes in calm weather. Flutter