Vibration control at extreme temperatures
Insufficient control of vibration propagation can cause critical failures and ultimately, total breakage in aircrafts. Control of vibrations generated in the counter-rotating open rotor to the fuselage was the aim of the project Z DAMPER(opens in new window) (Z-coupled full system for attenuation of vibrations). The simplest solution is to increase the elasticity of connections between the rotor and the main body of the aircraft. However, this approach to suppress vibrations is limited to average temperatures and relatively high excitation frequencies. Moreover, a significant increment in the aircraft weight is involved. Z DAMPER engineers developed a prototype device for matching mechanical impedances to control vibrations of both low and high frequency ranges more efficiently. Never had impedance coupling been used for vibration damping purposes. In a nutshell, the device is composed of three elements: a ‘slow stage’ attached to the vibrating rotor, a stator fixed to the fuselage, and an internal ‘fast stage’. A contactless linear magnetic gear configuration ensures mechanical impedance matching between the slow and fast stages. The fast stage can move up to 10 times quicker than the slow stage. On the other hand, the force exerted by the slow stage is up to 10 times larger than that of the fast stage. This configuration allows to isolate external vibrations and to internally transform them into high-speed vibrations subsequently damped. Z DAMPER technology has additional advantages when compared to existing vibration damping systems. The absence of contact between movable components minimises wear, and therefore, no lubrication is needed. Thus, minimum maintenance is required while the device lifetime surpasses mechanical ones. This is the first vibration damping technology to reach temperatures as high as 250 ºC and as low as -200 ºC that can cope with high dynamic forces. Moreover, it can be applied to enhance the efficiency of other damping systems, like eddy-current dampers.