抄録
Computer-aided engineering is widely used in mechanical engineering to analyze the noise and vibration performances of components and assemblies. Recently, a more detailed finite element model (FE model) with a large number of degrees-of-freedom has been in use, owing to developments in computer technology. This FE model is better suited to examining the effects of changing physical parameters such as the material stiffness and structural, details. On the other hand, with the FE model it is difficult to develop effective countermeasures for reducing noise and vibration because of the increasing number of modes in unit intervals of frequency. For such a problem in the frequency range of high mode density, earlier studies presented different mode classification methods. Representative modes among mode groups are useful for developing countermeasures. However, studies have not presented a method for extracting representative modes by which the frequency response function (FRF) can be recalculated. In this paper, a new method of extracting representative modes is proposed in order to recalculate the FRF with a smaller number of modes. First, a mode grouping method is employed with a beam and spring-mass model. Second, a new FRF in a mode coordinate system is derived by summation of the FRFs of the same mode group. Representative modes are derived by the FRF in a physical coordinate system and a new FRF in a modal coordinate system. Finally, we present an approach to reduce the vibration for an evaluation point using the representative mode.
