| dc.description.abstract | When the rotating parts inside the rotating mechanical system have an unbalanced
mass, vibration will be caused during the rotation process, leading to noise damage and
reducing service life of the mechanical system in the long run. In this study, a particle
damper is applied to the engine shaft to correct the dynamic balance state. At the same
time, the collision and friction between the particles and the wall in the particle damper
suppress the vibration of the rotating mechanical system, achieving the effect of dynamic
balance correction and vibration suppression. To explore the effectiveness of particle
damper in suppressing vibrations, the engine shafts designed with equivalent mass
without particle dampers and the engine shafts with particle dampers both achieved
dynamic balance correction to the G2.5 level in ISO1940 dynamic balance specification,
attaining similar dynamic balance allowances. After dynamic balance, the dynamic
response of the two kinds of engine shafts were compared, and the effects of operating
speed, load torque and particle size on the dynamic response of the engine shaft were
systematically explored. The dynamic physical properties include the root mean square
value of the acceleration in the time domain signal, the power spectral density and energy
in the frequency domain signal.
The research findings are summarized below: (1) In the comparison excitation
frequency of frequency domain signals, at each speed, the power spectral density and
energy of the engine shaft with particle dampers are lower than those in the engine shaft
with equivalent mass without particle dampers, showing that the particle damper provides
the effect of vibration suppression; (2) At low speed with low torque and high speed with
high torque, the engine shaft with particle dampers relative to the engine shaft with
equivalent mass without particle damper has a significant vibration reduction effect.
However, at low speed with low torque, the vibration reduction effect of particle damper
with 4 mm particles shows a decreasing trend; (3) The effect of particle size was explored
and three kinds of particle diameters (2 mm, 3 mm and 4 mm) were used. The particle
damper with 2 mm particles exhibits the most stable and significant performance in
vibration suppression; (4) Through experimental validation, by using particles of
appropriate particle size and conducting dynamic balance correction, the particle dampers
can reduce the vibration of the engine shaft effectively. | en_US |