Accelerated life testing of harmonic driver in space lubrication

For mechanical moving components in space applications, the accelerated life test for the verification of reliability is very important. Since traditional methods of the accelerated life test for liquid lubrication have some limitations, a new method is proposed in this paper, in which the harmonic driver is used as the object of study. First, the life test of a harmonic driver is performed in vacuum. The results show that the adhesive wear caused by asperity contact at the wave generator-flexspline interfaces is the crucial factor governing the life of harmonic driver. To clarify the lubricant film behavior at the wave generator-flexspline interface, a mixed lubrication analysis is conducted. Furthermore, the scheme of the accelerated life test is discussed. The speed and load are selected as the acceleration stresses of the test, while the load supported by asperity contact is defined as the characteristic quantity of the life and used to select acceleration factors. Finally, accelerated life tests under different working conditions are conducted to validate the results of the theoretical analysis.