Abstract:

By investigating the influence of thermal expansion coefficient of spacer on the thermal preload of space manipulator, the theoretical guidance is provided to establish the model of the thermal preload on space manipulator and the failure that caused by alternating temperature. By taking the shaft-bearing system in space manipulator as a research object, the prediction model of thermal preload on space manipulator is established. In addition, a method that can mitigate or eliminate the thermal preload on space manipulator by choosing the best material for the spacer is proposed. Based on the changeless structure of shaft-bearing system and the compatibility deformation and the influence law of thermal characteristic of spacer material on thermal preload of space manipulator, the mitigating effect is investigated to show the effect of different spacer material on the thermal preload of space manipulator. The result indicates that, the preload increases after the interception by the friction at the bearing fit when the axial force acted on the bearing increases; if the alternating temperature increases, the bearing preload will increase and the magnitude interference of inner ring will decrease. Beyond that, the possible failure modes are analyzed as well. Furthermore, the influence results are obtained by using different thermal expansion coefficient. When the thermal expansion coefficient is less than 7×10^-6m/℃, the change rate of thermal preload decreases with alternating temperature, and the thermal expansion coefficient increases; when the thermal expansion coefficient is more than 8×10^-6m/℃, the change rate of thermal preload increases with alternating temperature; if the thermal expansion coefficient is between 7.6×10^-6m/℃ and 7.7×10^-6m/℃, the thermal preload stimulated by alternating temperature will be mitigated sharply or eliminated.

Key words: bearing, preload, space manipulator, thermal characteristics, alternating temperature