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The crankshaft is one of the most important components of the marine diesel engine, its high cost, poor working conditions. Marine diesel engine crankshaft damage, not only to be a fatal destruction, may also be a direct threat to the safety of navigation of the ship. Currently, people usually are in the design phase of the crankshaft stress accounting, or check after the accident on the crankshaft. However, due to the installation and commissioning of error, diesel engine cylinder firing uneven, mechanical wear, aging, as well as the ship shafting vibration lost medium reason crankshaft actual state of stress is difficult to maintain the state of theoretical design, diesel engine or the tail shaft shafting fracture accident repeated have occurred. Shafting crack online diagnosis can be effectively avoid machine ruined accident, greatly reduce the losses caused by the accident. The the MMM testing nondestructive testing technology is developed in the past decade a new type of metal, this method is applied to the crankshaft monitoring of such ferromagnetic components stress concentration points, its crack fault detection. Simple sensor of magnetic memory using non-destructive testing rules, does not affect the measurement diesel engine running, suitable for long-term online monitoring. The main work of this article: 1 to study the mechanism of magnetic memory techniques. Magnetic memory testing needs through the magneto-elastic effect is derived formula specimen piezomagnetic effect. Through experiments, to verify the existence of the phenomenon of the magnetic memory, and an important characteristic of the detection of the magnetic memory, i.e. different generatrix scanning along the test piece obtained in HP (Y) is a zero crossing of the position substantially coincident with the pre-crack, i.e. along The the different bus detection of the specimen can be found the position of the stress concentration. Crack Fault of Diesel Engine Crankshaft collection of data, its analysis and study of the early crack development of the law. Collected by the ship repair companies, maintenance departments and literature classification, filtering the typical the shafting crack sample. Fracture mechanics theory, with reference to the parameters of the stress intensity factor crack propagation criteria, analysis of the crankshaft of the fracture process. 3, build a simulation test bench simulation validation process of cracked crankshaft. The design of the bench in a small diesel engine as the main shafting variable speed, variable load as well as the temperature change of the crankcase and oil mist characteristics, magnetic memory testing to be realized, and has good practicality and reliability. , And explore the diesel engine crankshaft magnetic memory signal of variable speed, variable load and variable temperature dynamic characteristics, to further improve the hardware and software features of the diagnostic system and real-time, to create the conditions for further scientific research.
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