SMART SNUBBER/DAMPER FOR FIVE FOLD INCREASE IN DAMPING OF BEARINGLESS MAIN ROTOR BLADES
Agency / Branch:
DOD / ARMY
Snubber/damper damping performance is severely limited by component size and load constraints yielding insufficient RLM damping. Solutions using existing technology lead to excessive snubber damper size and weight to accommodate all operating conditions.
Also, current snubber/damper designs are not sufficiently reliable and have limited life.
High damping is required for stabilizing ground and air-resonance (rotating frequency of interest typically 0.3-0.7P). However, simply increasing the damping of snubber/dampers designs will also increases the 1P lead-lag associated loads and reduce related component lives
One solution to the above problem would be to design a ¿smart¿" snubber-damper that takes advantage of the superimposed 1P motions by producing damping forces that oppose ¿¿lag motions but produce zero or low force when the net damper loads are not favorable for suppressing ¿¿lag motions. This is not possible using conventional passive dampers because passive elements like relief valves, orifices, produce forces that oppose the net velocity even if the resulting force excites the regressive lag mode! The new active concept arises from the recognition that the net damper force, i.e. from the combined ¿¿lag and 1P motions, often produces forces that can be advantageously used to suppress ¿¿lag response, thus converting a chronic difficulty in damper technology, unwanted 1P motions, into a benefit. The proposed concept relies upon two actions:
1) Minimizing the net damper force when it is in the same direction as the ¿¿lag velocity. This avoids adding energy to the ¿¿lag mode. This would be done by selectively opening a controlled valve to equalize the pressure in the damper chambers thus not allowing pressures to build.
2) Maximizing the net damper force when it opposes the ¿¿lag velocity. This would extract energy from the ¿¿lag mode. This would be done by selectively closing a controlled valve to maximize the damper load.
Small Business Information at Submission:
MATERIALS TECHNOLOGIES CORP.
57 MARYANNE DRIVE MONROE, CT 06468
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