Study On The Evaluation Methodology For The State Of Marine Diesel Propulsion Shafting Systemb

As an important part of marine machines, marine diesel engine propulsion shafting system is vital to the safety and navigation. Especially, with the development of vessel large-sized, the significant increase in the propeller’s size and mass lead to the structure and function of the shafting line changed accordingly and the stiffness of the hull reduced. The state of the marine diesel engine propulsion shafting system varied under the effects of ship loading, sailing area, and sea condition, which result in excessive wear of the bearing and fatigue failure of the shaft, threatening safety and normal sailing. Therefore, it is an urgent to understand further the conditions change and the service performances of the integrated system marine diesel engine-shafting.Firstly, based on the nonlinear dynamics theory, the initial state of shafting system alignment was evaluated with the transfer matrix calculation method and the finite element method in this paper to verify the correctness of the reasonable shafting alignment. And calculating results of three ships, ie.118000DWT,110000DWT and 57300DWT were presented for examples in this paper.Secondly, an experiment-bench for marine diesel engine propulsion shafting system including engine-bearing-shaft has been established depending on the condition monitoring technology. Furthermore, experiments on the orbit state of the shafting system are implemented under deferent conditions and real-time data is collected. The wavelet package is used to de-noise, reconstruct, and purify the original signal for revealing the dynamic characteristics and the motion patterns of the marine diesel engine propulsion shafting system. The result showed that the characteristics and motion patten of the shafting system can be described by the orbit state.Thirdly, in order to monitor alignment state and dynamic status of the marine diesel engine propulsion shafting system, stress-strain measurement are also carried out on the experiment-bench by using wireless telemetry technology. With these data, bending moment, torque, rotary speed, and bearing load are calculated, a reverse algorithm is achieved to evaluated the shafting state.Finally, with the help of slip-ring sensing(SRT) technology and IGOR PRO tools, based on conservation law of energy, an evaluation method is established by combining the experimental data and theoretical calculation to reveal the dynamical characteristics of the marine diesel engine propulsion shafting system and the general rules for its service performances. Its validity has been verified with experimental data in this paper, too.With the monitoring technology, a set of evaluation methods for the state of the marine diesel engine propulsion shafting system are implemented by theoretical analysis and collecting multi-field data of static and dynamic parameters including design, installation and service stages. It is achived in this paper to realize an approach of comprehensive evaluation for the full life-cycle of the marine diesel engine propulsion shafting system.