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Outline
To address the issue of excessive engine exhaust smoke and insufficient power occurring after 275 km of operation in a certain engine turbocharger, a systematic analysis of the failed turbine shaft is conducted using methods such as macroscopic inspection, scanning electron microscopy analysis, metallographic observation, and hardness testing. The results indicate that the turbine shaft fracture is a low-stress, high-cycle fatigue failure under significant stress concentration. The fracture originated from a severely scratched area at the fillet caused by poor grinding processing. The root cause is identified as poor lubrication leading to dry friction between the shaft and bearing, subjecting the bearing to abnormal alternating stress. The study concludes that although the machining defect created a stress concentration source, the abnormal operating condition (dry friction caused by oil shortage) is the primary factor triggering this premature fracture.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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