Influence of flexible interface on the performance of whole spacecraft vibration isolation

Purpose - As the installation of the vibration isolation device to the spacecraft for the whole spacecraft vibration isolation, the interface structure is typically modeled as a rigid structure during the design phase. However, the flexibility of the interface structure does exist for a large-sized adaptor. This is a source of uncertainty and could reduce the reliability of the system. It is necessary to investigate the influence of this type of flexibility on the vibration isolation performance in an engineering practice. This paper aims to address this situation. Design/methodology/approach - The vibratory transmissibility from the bottom of the isolator is generally used to evaluate the performance of the vibration isolation. By introducing the interface flexibility from both the adaptor and the vibration isolation device, a planar model which includes a flexible beam representing the interface structure is established to study the influence of this type of flexibility on the vibratory transmissibility. Findings - It is found that, when this type of flexibility is included, an extra low-frequency mode dominated locally by the interface structure is induced, and then a significant resonance appears in the vibratory transmissibility of the vibration isolation device at a low frequency. Originality/value - The vibration isolation performance may be over-estimated in the design by taking the interface as rigid. The inherent flexibility of the interface structure, on the other hand, may degrade the performance of the vibration isolation device and degrade the function of the rotation constraint device added into the vibration isolation device.