Aiming at the complex mechanism and operation characteristics of the mechanical system of diesel engine on RO-RO passenger ship,a multi-component nonlinear vibration signal decomposition method and vibration characteristic parameter extrac-tion strategy are proposed.The signal is decomposed into intrinsic mode function(IMF)components via empirical mode decompo-sition and restrained the end effects in empirical mode decomposition(EMD)by symmetrical extension.The sensitive component is extracted by the correlation.The characteristic frequencies are matched according to the amplitude demodulation spectrum via 4 order high energy operator(4th-HEO).The proposed method is illustrated by the three-dimensional vibration signals under 0 load and 100 load operation conditions of the RO-RO passenger ship.The results show that the analysis performance of vertical signals are better than other axial signals.And for the 9-cylinder 4-stroke diesel engine,the amplitudes of 0.5 times and 4.5 times are very prominent,and are more sensitive to load changes.
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