Design And Analysis Of A Ball-type Vibration Isolator With Quasi-zero-stiffness Characteristic

Recently, quasi-zero-stiffness(QZS) vibration isolation technology has gradually become a good solution for low frequency vibration isolation area. The basic idea is to combine the positive and negative stiffness to get high static stiffness and low dynamic stiffness at the equilibrium position, which can reduce the natural frequency, and broaden the frequency range of vibration isolation. A compact QZS isolator with a ball-cam mechanism is proposed as a solution for the low-frequency and micro-amplitude vibration isolation.The main contents of this work is list below:1. Existing QZS isolators can only perform atenuation effect under the condition of large vibration amplitude, which limits applications in engineering. A new design idea of using ball contact is proposed. This mechanism is to increase vector angle of contact force through two pairs of balls contact, thereby to increase the sensibility of the negative stiffness in millimeter vibration. This mechanism enables to achieve vibration isolation at millimeter amplitude level.2. The matching condition for the parameters of the QZS isolator was abtained through analyzing the relation between the load and displacement on the ball contacts. Furthermore, the dynamic model of the isolator was established, and the frequency response characteristic and the vibration isolation performance were analyzed by using a harmonic balance method. The effects of excitation amplitude, damping on the response and jumping phenomenon were also discussed.The error analysis of ball contact offset is carried out. All of these analyses lay a foundation for the prototype design of the QZS isolator.3. According to the QZS princeple, with the continuous effort for the improvement of structure design and manufacturing process, a new ball-type QZS vibration isolator with elastic beams is designed. The experiment proved that if the inclined spring is substituded by rolling balls of small diameter, the negative stiffness mechanism can fully involved in small vibration. The ball-type QZS vibration isolator can obviously reduce the starting vibration isolation frequenc y and expand scope of vibration isolation and posses much lower transmissibility. In this paper, the effects of different pre-compressed magnitudes and different exciting force amplitudes on the performance of vibration isolation were also discussed, and experimentally verified the effectiveness of the isolator performance.