Implementing Simulationx in the Modelling of Marine Shafting Steady State Torsional Vibrations

Abstract

Marine propulsion shafting systems are exposed to torsional vibrations originating from excitations in their prime movers and propellers. It is essential to analyse their steady state response in the earliest stage of ship design. The paper describes the implementation of SimulationX software based upon simulation modelling for these calculations. This software can be used either by the design office of the shipyard or by the classification society for verification within the plan approval phase. Some specifics of the input data preparation are briefly discussed. In addition, the simulation results depend on the modelling approach chosen. For these reasons, the real two-stroke Diesel engine ship propulsion system was chosen and several different models were implemented for system modelling. SimulationX calculation results are compared with those of two well-known and field-proven programs that use an analytical approach. Finally, the results are compared with the measurements performed on the actual newly built ship. Discussion reviews the selected SimulationX model, and its verification and validation in the case of engine cylinders with normal ignition.

A Novel Fault Diagnosis Method for Marine Blower with Vibration Signals

“…The short-time Fourier transform obtains the relationship between time and frequency by adding a narrow window function, but it still cannot meet the requirements of high frequency resolution in the low-frequency region and high time resolution in the high-frequency region. Non-intrusive vibration measurement is used for effective identification of journal bearing operation in rotating machinery [11,12], but the vibration signal is a nonlinear and non-stationary signal, which is not suitable for analysis with the Fourier transform. Although WT and EMD are effective in processing nonlinear and non-stationary signals, they also have some problems.…”

Influence of solid particle contamination on the wear process in water lubricated marine strut bearings with NBR and PTFE bushes

“…However, such agents are not stable enough to achieve a sufficient effect on the surfaces of bearings; an acceptable lubrication is a combination of many contributing factors [3]. Problems related to premature wear of the aft stern bearings are reflected in many publications and are related to their lubrication [4], [5] as well as factors influencing the efficiency of this lubrication, such as vibrations [6], [7] or the dynamics of the shaft movement [8], [9].…”