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 |  موضوع: بحث بعنوان Acoustical Optimization of a Train Gearbox Based on Overall System Simulation الإثنين 14 سبتمبر 2020, 1:02 am | |
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أحضرت لكم بحث بعنوان
Acoustical Optimization of a Train Gearbox Based on Overall System Simulation
Jan Troge1, Welf-Guntram Drossel, Eric Hensel, Sebastian Zumach, Jan Bräunig
Fraunhofer Institute for Machine Tools and Forming Technology IWU, Dresden, Germany
و المحتوى كما يلي :
ABSTRACT
The present article deals with the simulative representation and optimization of acoustical properties of a train
gearbox with one helical gear stage. At first, a dynamic model of the initial gearbox based on manufacturer
construction parameters was built up. Based on this model, the gear mesh excitation as a main source of
structure-borne sound has been calculated. Within the simulation model relevant influences on gear mesh
excitation e.g. housing and shaft deformations or bearing stiffnesses have been considered by including
flexible structures. By reference to these simulation results, the first optimization step was to change gear
micro geometry to reduce system excitation. Based on analysis of system dynamics, as well as the calculation
of averaged surface velocities, critical rotational speeds have been identified for a given input torque. For
these critical rotational speeds, interface parameters, which are necessary for the following numerical sound
radiation simulation, have been determined. On the basis of the simulated mode shapes and operational
deflection shapes, a structural optimization of the gearbox housing was performed by considering installation
space and mass specifications. The acoustical characterization of different optimization variants has been
realized by comparing the emitted sound power levels determined by numerical simulation.
Keywords: Gearbox, Dynamic Simulation, NVH
CONCLUSION
In this paper, a simulation based method for noise prediction and acoustical optimization of a railway gearbox
has been presented. The overall system approach can be used to identify critical speed ranges of the gearbox
from an acoustical point of view and quantify the sound radiation during operation. To significantly reduce
modeling and calculation time, the sound radiation in the complete rotational speed range has been estimated
using the basic equation of machine acoustics. The comparison to the numerical calculation showed that the
assumptions are valid and that the correlation to the numerical results is quite good. To reduce the overall
sound radiation of the gearbox in critical speed ranges, two ways of acoustical optimizations have been
performed in parallel - micro geometry optimization of the gears and structural optimization of the gearbox
housing. The sound radiation characteristic of the gearbox can be influenced only frequency selective by a
housing optimization which is due to a shift of relevant operational deflection shapes in the frequency domain
caused by mass and stiffness changes. A significant overall reduction of the sound radiation can be achieved
by lowering the excitation potential of the gear mesh by changing the micro geometry of the gears. With the
help of a parameter study (DoE), the optimal gear geometry parameters could be determined to reduce the
first gear mesh order as the target parameter. In addition, measurements on a test rig of the project partner
have been performed which showed similar results in terms of the sensitive parameters for lowering noise
radiation. The presented simulation approach can also be applied to different types of gearboxes and is an
important tool for the acoustical development of gearboxes starting in the early design phase.
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