基于压电摩擦阻尼的四参数隔振系统等效建模与频变阻尼特性分析

在轨卫星搭载的高精度有效载荷对环境微振动异常敏感，从而对隔振系统的振动衰减性能提出了更高的要求。传统两参数被动隔振系统提高隔振性能时，常采用添加定常阻尼进行能量耗散的方式，但存在低频共振峰抑制与高频快速衰减不能兼顾的固有矛盾问题。为了解决这一问题，一种能够实现阻尼特性基于频率变化的四参数隔振系统被提出，采用归一化方法建立其系统传递率与等效阻尼理论模型，并与两参数和三参数隔振系统进行对比分析。基于四参数系统的频变阻尼等效理论，设计一种基于压电陶瓷致动器产生摩擦阻尼的具象化四参数隔振系统，考虑非线性摩擦阻尼的融合问题，并分析中间等效质量参数对阻尼频变特性的影响规律，最后对其频变阻尼特性和隔振性能进行了仿真与实验验证。结果表明：时域上，四参数隔振系统对随机信号的隔振率达到91.1%；频域上，相较常值小阻尼系统，四参数隔振系统在低频共振处的峰值性能提升5.46dB，且高频段保持相近的快速衰减，表现出低频大阻尼、高频小阻尼的频变阻尼特性。仿真与实验结果均表明，系统能够解决被动隔振系统中存在的高低频隔振性能之间的矛盾问题。

Equivalent Modeling and Frequency-dependent Damping Characteristics Analysis of a Four-parameter Isolator Based on Friction Damping

The high-precision payloads carried by on-orbit satellites are extremely sensitive to the environmental micro-vibration, which puts forward higher requirements for the performance of vibration isolators. In order to improve the vibration isolation performance, the traditional two-parameter passive vibration isolator usually adopts the method of adding constant damping for energy dissipation, but there is an inherent contradiction between the suppression of resonance peaks and the rapid attenuation of vibration at high frequency. To solve this problem, a four-parameter vibration isolator with damping varying with frequency is proposed. The theoretical model of the system transmissibility and equivalent damping are established by normalization method, and the vibration isolation performance is compared with the two-parameter and three-parameter vibration isolators. Based on the theory of frequency-dependent equivalent damping, a specific four-parameter vibration isolator with friction damping generated by piezoelectric ceramics actuator is designed, the fusion problem of nonlinear friction damping is considered, and the influence of the intermediate equivalent mass on its frequency-dependent characteristics of damping is analyzed. Finally, the frequency-dependent damping characteristics and vibration isolation performance were verified by simulation and experiment. The results showed that: in the time domain, the isolation ratio of the four-parameter vibration isolator for random signals reaches 91.1%; in the frequency domain, the peak value of the four-parameter vibration isolator at the natural frequency is 5.46 dB higher than the system with small and fixed damping, and the rapid attenuation of vibration is maintained in the high frequency range, which exhibits the frequency-dependent damping characteristics of large damping at low frequency and small damping at high frequency. Both the simulation and experimental results show that the isolator can well overcome the contradiction of vibration isolation performance between the high-frequency and low-frequency existing in passive vibration isolators.