20-01-2015, 04:50 AM
I need some help regarding fatigue on crankshaft of diesel locomotive. Provide me the notes
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fatigue on crankshaft of diesel locomotive
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I need some help regarding fatigue on crankshaft of diesel locomotive. Provide me the notes
28-03-2017, 01:00 PM
The crankshaft of a six-cylinder, 225-hp diesel engine that drove a small locomotive. About nine months after the installation, there was a drop in oil pressure to damage to the No. 5 crank bearing. A small lip present on one side of the discontinuity apparently served to scrape the bearing material. The defect was softly stoned, a new bearing fitted, and the engine returned to serve. The engine worked satisfactorily for another twelve months until the fracture of the crankshaft through crank No. 5 ensued. The fracture revealed a complex twist fatigue failure. Microscopic examination revealed that the pin had been hard chromed and that the plating followed the curved edge of the external limb of the defect. This crank contained an inherent defect in the form of an inclusion of slag or crack located on the surface.
A failure investigation has been carried out in three cases of failed diesel engine crankshafts used in rail and forged carbon steel compounds. The chemical composition and mechanical properties of the crankshaft material were evaluated, including tensile properties, microhardness and hardness. Examination of the crankshaft shows that all failures occurred after a fatigue process. Fault zones include the observation of fractured surfaces, showing the presence of semi-elliptical beach marks around the fracture origins, indicating their progressive growth. Initiation of cracks can occur as a result of mechanical and thermal fatigue loads due to the high stress concentration in the radius of the threads and the unusual friction between the bearings and the bearings, respectively. However, the propagation of cracks was only attributed to the mechanical fatigue produced by the cyclic loads of bending and twisting.
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