Ribs effects in acoustic radiation of a gearbox — their modelling in a boundary element method

Boundary element methods are nowadays currently used for acoustic radiation prediction of complex mechanic structures. Many of those structures contain an important account of ribs. The present paper deals with the acoustic influence of ribs and their modelling in a boundary element method. The influence of ribs is theoreticaly discussed and three different physical effects are distinguished : the “vibrating”, the “obstacle” and the ”source” effects. Further the modelling of ribs in boundary element meshes is discussed. An application to an automotive gearbox housing is then proposed. The vibrating behaviour of the structure is calculated with a finite element model, which has been updated thanks to an experimental modal analysis. The boundary element modelling necessity and the acoustic effects of the different ribs of the gearbox housing are studied.