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Summary, Conclusions, and Recommendations
Two methods for detecting sun gear faults have been de-veloped and demonstrated on a full-scale OH-58 transmis-sion. The test components were chosen from a set of parts damaged from a previous endurance test.
The main goal of this research was to determine if it was possible to isolate the dynamics of the sun gear and detect any damage, independent of the other components. This higher level of interrogation improves on any indica-tion of damage from the TSA data by actually con.rming the source, thus providing an effective means to reduce the number of false alarms.
Planetary gear diagnostics have been demonstrated to be an effective tool to detect planet gear damage, but detecting faults on the sun gear remains a challenge. One reason for
(a) (b)
(a) (b)
this is because the sun gear’s dynamics is determined in-directly, through a meshing planet gear. The dynamics of the planet gear and sun gear are commensurate; thus, time-synchronous averaging could not be used as a separation tool as it may be for the sun and bevel gear components. In addition, the low hunting tooth ratio between the sun gear and the ring gear allows only a small subset of sun gear teeth to be compared directly. This is different than the case for PGVS where an extraction of dynamics associated with each tooth, at the same roll angle, can be made. This al-lowed for the creation of a Vibration Separation Vector that is highly periodic and lends itself to analysis tools that look at deviations from this periodicity, such as the FM4 condition indicator. Another obstacle arises from the non-synchronous meshing and unequal spacing of the system’s planets. This adds a further level of complexity when work-ing with the waveforms, requiring the need to separate data into different TSA groups.
Both methods performed well in detecting damage for the multiple fault case. The SGVS -SASP method produced dominant tooth mesh waveforms in its Vibration Separa-tion Vector with spacings in accord with a sun gear mesh groups. In addition, the details of the individual waveforms are preserved, possibly allowing additional analysis to de-termine the level of damage for prognosis. Although some Vibration Separation Vectors for the single tooth spall case indicated some singular tooth mesh activity, the .nd-ings from inspecting the waveform as well as the FM4 pa-rameters was inconclusive.
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本文链接地址：Sun Gear Fault Detection on an OH-58C Helicopter Transmission(29)
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