The finite-element model of a 3D, coupled gear-rotorbearing housing system with emphasis on multistage gear transmission of a heavy duty marine gearbox has been developed successfully. The purpose of the study is to analyse the gearbox vibration and noise response because of both the internal gear meshing and the external shaft related dynamic excitations. Both free and forced vibration analyses are performed. In the free vibration analysis, the Lanczos method is applied. The forced response analysis is based on the mode superposition method. The proposed simulation results also serve as the basis for gear dynamic optimization of heavy duty marine gearboxes. The following specific findings are derived from this computational study. The simulated contact patterns of the helical gear pairs have been applied to construct the timevarying gear mesh stiffness for a single tooth pair as well as for a complete gear pair. The results give the ability to construct the non-linear gear mesh coupling as well as the internal parametric excitation of various stages of the gear transmission system. The modes of the marine gearbox system are shown to be quite complex due to the combination of torsion, translation, swing, and bending ofthe gearbox structure. However, none of the input and output meshing frequencies is close to the natural frequencies and thus avoiding a potentially catastrophic resonance response. The predicted velocity responses of the bearing blocks have been found to remain below the critical 4.5mm/s for the class B gearbox under investigation. In fact, the vibration amplitudes of the input and output bearing blocks are relatively small, which points to a reasonably satisfactory gear dynamic performance. The peak noise response appears near the meshing frequency of 493.33 Hz with an estimated acceleration noise level of 120 dB. A vibration experiment of the gearbox was conducted. Results indicate that the maximum rootmeansquare velocity of the bearing housing is 3.5mm/s, while the maximum value of the noise caused by the structure is 130 db. Experimental results of the vibration velocity and the structure noise are in accordance with the theoretical ones, which verify the correctness of the numerical simulation.
Dynamic analysis of a heavy duty marine gearbox with gear mesh coupling
Dynamische Analyse eines verzahnten Hochleistungsgetriebes für die Schifffahrt
2009
17 Seiten, 25 Bilder, 6 Tabellen, 20 Quellen
Article (Journal)
English
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