2019 年 85 巻 871 号 p. 18-00260
Technology development to improve road induced noise is necessary with the market expansion of the electric motor drive vehicles, because road induced noise is noticeable under no engine noise condition. One of the effective ways to achieve good performance is to avoid the natural frequencies of vehicle bodies from dominant frequencies of the transmitted forces between a suspension and a vehicle body, which vary as the characteristics of road surfaces. For this background, this paper proposes a new method for shifting the natural frequency of coupled two vibration systems which are connected at multi-points by coupling springs assuming semi-active control. Firstly, based on the sub-structuring method, the relation between column vectors in the compliance matrix at connection points of two systems is analyzed to make clear the condition of resonance occurrence. This condition is equivalent that all column vectors of the compliance matrix at connection points exist in a hyperplane. Secondly, utilizing the independence of each coupling spring’s degree of freedom, simple equation to calculate a coupling stiffness is derived to satisfy the condition of resonance occurrence. Finally, in a feasibility study, the method was applied to two beams connected with three translational springs. It is showed that the proposed method can shift an initial natural frequency to target frequency with a simple calculation.