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Detecting damage on planet gears using vibration sep-aration has been shown to be successful. (Ref. 26) How-ever, detecting damage on the sun gear continues to be a challenge. This is because its dynamics need to be as-sessed through the planet gears introducing a higher degree of complexity. Figure 9 gives a .owchart of the vibration separation processes used in this research. There are three stages: Acquisition/Interpolation, Extraction, and Assembly. The Acquisition/Interpolation stage encompasses the simultane-ous data collection of the vibration and once-per-revolution (OPR) signal based on the output shaft’s rotation. Using the OPR signal, the data is partitioned into individual cycles. Each cycle is optionally .ltered and interpolated to N points and then stored as a column in the Interpolation Matrix. This 2D matrix has length, N and width, Nextract , which de-pends on the number of complete cycles in the measured data. The next step is the Extraction stage. Each column of the Interpolation Matrix represents a full carrier cycle and within each carrier cycle there is a point that repre-sents when planet Pi and accelerometer Aj are aligned. This point, Ni j, is referred to as the extraction index. Given the extraction index, Ni j and a pre-determined number of point to extract,缸E , data is extracted and stored into a structured matrix called the Assembly Family. The Assembly Family is a 4-D variable which contains a .eld for each accelerom-eter where each .eld contains a 3D matrix. Each 3D matrix has layers corresponding to each planet and each column corresponding to a given carrier cycle. The next stage is Vibration Separation Assembly where there are 2 options: planet gear vibration separation (PGVS) and sun gear vibration separation (SGVS). In this stage, the extracted data in the Assembly Family is as-signed a mapping index, Ni j .., that depends on the planet or sun tooth engaged at the time the data was extracted. This parameter governs the positioning in the .nal Vibra-tion Separation Vector of that extracted data set. Differ-ent methods of assembly are used. For PGVS, the sin-gle accelerometer / single planet (PGVS-SASP) method is used to create the Vibration Separation Vector that corre-sponds to a given planet. For SGVS, either an SGVS-SASP method or an alternative single accelerometer / multiple planet (SGVS-SAMP) method is used to generate the .nal Vibration Separation Vector corresponding to the dynam-ics associated with the sun gear. The SGVS-SASP method allows the accelerometers to ”see” the sun gear through only one planet, and SGVS-SAMP allows them to ”see” the sun through multiple planets. Damage detection CIs are then applied to the Vibration Separation Vector. This paper focuses on the SGVS-SASP method. 直升机网 www.helicopter.cn 直升机翻译 www.aviation.cn 本文链接地址：Sun Gear Fault Detection on an OH-58C Helicopter Transmission(11) |
