INFLUENCE OF STRUCTURAL PARAMETERS AND EXCITATION ON MODAL BEHAVIOUR OF GEARBOX HOUSINGS

The main requirement for the gearboxes is a high load carrying capacity, but as a result of increasing of environmental awareness, and low sound excitation behavior becomes more and more important. Regarding this fact, it should be notice that the spectra of the emitted noise of gearboxes are in direct correlation with the modal response of their housings, which is consequence of excitation by the internal disturbances. Excitation of certain modal shapes (modes) depends on frequencies of the disturbances and the elastic deformations they cause. Modal damping of the modal vibrations, as a result of complex processes of the wave motion in the walls of the housing, is also a key parameter of the modal behaviour. In addition, modal behaviour, as characteristic structure property, is determined by the material properties (mass, stiffness and damping) and boundary conditions of the structure. Change of any of those characteristics leads to changes of modal behaviour. The aim of the paper is elaboration of the mechanism of excitation of natural vibrations of a gearbox housing including both the effects of excitation disturbances (direction and place of action, frequency, damping) and structure parameters (shape, dimensions, material) of the structure. Numerical and experimental methods were applied and their results allowed for analytical clarification of processes in elastic structure of system.