基于正负刚度并联的低频隔振器研究

为了能够抑制微振动对在轨运行航天器造成的不利影响，提出了一种由螺旋柔性弹簧（SFS）与磁性弹簧并联构成的低频隔振器；其中，螺旋柔性弹簧作为正刚度元件为系统提供承载能力，并通过有限元建模对其轴向刚度特性进行了数值分析；由两两相吸、同轴配置的3块环形永磁体构成的磁性弹簧为该隔振系统沿轴向提供负刚度以降低系统的固有频率；基于等效电流模型分析讨论了该磁性弹簧的磁刚度特性，并在平衡位置附近对磁刚度作了线性近似。通过分析所设计的低频隔振器与其相应线性隔振系统的位移传递率，比较了2种隔振器的隔振性能。研究结果表明：所提出的低频隔振系统能够有效地隔离低频微幅振动，降低系统的固有频率，进而拓宽了隔振频带；同时，进一步改善了隔振系统在共振区域附近的阻尼特性，有效地降低了共振峰值。

Study on a low frequency vibration isolator based on combined positive and negative stiffness

To suppress the adverse effects caused by micro-vibration on orbiting spacecraft, a novel low frequency vibration isolator which combines a spiral flexure spring (SFS) with a magnetic spring in parallel is developed; SFS is employed as a positive stiffness element to support the payload, and then the finite element model of SFS is adopted to analyze its axial stiffness. Moreover, the magnetic spring is fabricated by three coaxial magnetic rings that are arranged in attraction to provide negative stiffness for lowering the natural frequency of the isolator. The characteristic of magnetic stiffness is investigated based on the equivalent current model, and the linearization of magnetic stiffness near the equilibrium position is further obtained. The vibration isolation performance of the designed isolator and its corresponding linear system is compared through analysis of their displacement transmissibility. The results demonstrate that the designed low frequency vibration isolator can effectively isolate micro-vibration, lower the natural frequency of the isolator, and expand the bandwidth for vibration isolation. Additionally, the damping characteristic is improved near the resonance region, and the resonance peak is attenuated greatly.