A study of Kevlar suspension system in ADR for future mission

Abstract

The use of the ADR to provide a sub-Kelvin temperature environment is required for many space missions. The mechanical design of the ADR, including the use of Kevlar to ensure proper suspension of the salt pill, must minimize thermal conductivity between components while optimizing structural capability. Heat leakage reduction and vibration resistance have different focuses when determining the suspension system strategy and must be compromised. A dimensionless parameter $\phi$ representing the slenderness of the suspension is developed to quantify both heat leakage and vibration characteristics. At constant $\phi$, the diameter of the Kevlar cords has the greatest influence on vibration, followed by Kevlar cords’ length and then their number. As $\phi$ increases, although the reduction in heat leakage becomes less pronounced, the vibration response remains essentially linearly increasing. Therefore, designing the suspension according to this principle enables optimal stability after conforming to the maximum allowable heat leakage dictated by ADR's thermal design constraints. Also, research revealed that increasing preload from 10 N to 110 N has a negligible impact on vibration damping, benefiting from the comparatively superior axial stiffness of Kevlar. Therefore, it is sufficient to apply a certain amount of preload at rest to ensure that the salt pills remain fixed.