Vibration Isolation in Stewart Platforms via Phase-Change Low-Melting-Point Alloys for Tunable Stiffness

Micro-vibration mitigation is critical for spacecraft conducting precision-oriented space missions. In this paper, a novel Stewart platform incorporating a phase-change low-melting-point alloy (LMPA) is developed to achieve temperature-dependent stiffness modulation and broadband vibration isolation. First, based on the theory that variable stiffness alters the natural frequency of the structure, the feasibility of using the Stewart platform to achieve vibration isolation by changing the stiffness is obtained. Subsequently, a new Stewart composite structure was engineered by integrating LMPA and composite materials. Finally, compression and vibration tests were carried out on these platforms at temperatures of 25 °C and 60 °C. The results show that these Stewart platform composite structures have the response characteristics of variable stiffness, a variable natural frequency and widened frequency at different temperatures. The response properties of the platform are attributed to the phase change of the low-melting-point alloy at different temperatures. The effective vibration isolation frequency range of the composite Stewart platform can be widened to 31.6 Hz, and the vibration attenuation can reach up to 10 dB. This investigation establishes a novel methodology for developing adaptive vibration isolation systems using phase-change alloys, which are particularly suitable for spacecraft applications requiring precision motion control.