Numerical and experimental study on multi-axis Dynamic Vibration Absorber with multidirectionally supported mass

Abstract

Multi-mode damping of elastic vibration is required for efficient vibration reduction of lightweight structures. In this study, a multi-axial dynamic vibration absorber (DVA) is made, and the possibility of multi-mode damping is investigated. The multi-axial DVA consists of a mass sphere supported in multi-directions by eight springs, and the mass sphere vibrates in multi-directions: this yields multi-mode damping. From the theoretical analysis, it is shown that the natural frequency in each axis can be adjusted by changing the dimension ratio of the frame connecting the fixed points of these eight springs. In this paper, the numerical vibration analysis of the multi-axial DVA was firstly carried out using a finite element (FE) commercial software Ansys to check the theoretical analysis. The numerical results showed that introducing "slip" is necessary at the contact area between the supporting springs and the mass sphere. Based on the results of the FE analysis, a multi-axial DVA was developed and attached to a model of the underframe of a railway vehicle. Finally, a series of excitation tests for the underframe model was conducted, and the multi-modal damping was confirmed.