Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : December 09, 2021 - December 10, 2021
Two DOF Frahm damper attached to two DOF system is investigated. The anti-resonance frequencies of whole system correspond to the natural frequencies of the two DOF Frahm damper. Two combinations of the stiffness coefficients of the two DOF Frahm damper are derived for same natural frequencies. These combinations are different in the mode localization of the two DOF Frahm damper, and the differences between the natural frequencies of whole system on the both side of the anti-resonance frequency. The wide difference results in the efficient Frahm damper because the increment of the amplitude is suppressed although the excitation frequency is perturbed. In our previous study, same masses of the two DOF Frahm damper have been considered. However, the mass ratio of the two DOF Frahm damper affects the characteristics of the vibration suppression. In this study, the mass parameter α is introduced, and the two masses of the two DOF Frahm damper are expressed as (1−α)mα and (1+α)mα. The relationship between α and the natural frequency of whole system are obtained. To suppress 1st natural frequency of the main system, the stiffness coefficients without localized modes is more effective. However, to suppress 2nd natural frequency, the stiffness coefficients with localized modes is more effective.
