Modal characteristics and phase response of vibrator under excitation of sweep frequency

Abstract

To analyze the dynamic responses of vibrator, a vibrator-ground coupling vibration model considering sweep frequency is proposed based on half-space theory, and modal characteristics and phase response of the structure are investigated. Results show that the sweep frequency has a significant effect on the dynamic responses of the vibrator. The natural frequency of the vibrator changes with sweep frequency, and the resonance may occur at 2.071 Hz and 53.12 Hz. The vibrator has two mode shapes. The first-order mode shape is that the reaction mass and the baseplate move in the same direction and the structure is dominated by the reaction mass. At the second-order resonance, the reaction mass and the baseplate move in opposite directions and the baseplate dominates the system. The phase of the vibrator also changes with the frequency and varies greatly. The phases of reaction mass acceleration, baseplate acceleration and ground force suffer abrupt changes at about 2 Hz and 50 Hz. Especially, the phase of the baseplate acceleration experiences a 180° jumping at about 50 Hz. The abrupt change/jumping frequencies of the phase are basically the same as the natural frequencies, indicating that the resonance has significant effect on the vibrator output.

A unified probabilistic fatigue life prediction model for natural rubber components considering strain ratio effect

“…2 At present, research on the NR isolators mainly focuses on the former, and few is on the latter. 3 Studies show that the NR isolators are subjected to the cyclic action of variable-amplitude loads for a long time. Moreover, a large number of engineering practices show that NR isolators are prone to fatigue failure under the cyclic action of variable-amplitude loads.…”

“…In order to improve the performance of an NR isolator, it is necessary to focus on vibration features and analyze the fatigue characteristics 2 . At present, research on the NR isolators mainly focuses on the former, and few is on the latter 3 . Studies show that the NR isolators are subjected to the cyclic action of variable‐amplitude loads for a long time.…”