Diagnosis of engine cylinder liner wear based on fractal dimension of vibration signals

A novel diagnosis method of diesel engine cylinder liner wear based on ensemble empirical mode decomposition(EEMD) and morphological fractal dimension was proposed. In this method, firstly measured vibration signals were decomposed into a set of intrinsic mode functions(IMFs) by EEMD to separate noise interference from the IMF containing cylinder liner wear characteristic information, and then the morphological fractal dimension of IMF was calculated. Taking a six cylinder four stroke diesel engine for instance, the morphological fractal dimension of vibration signals measured from engine cylinder liner under 4 different states was analyzed. Results indicate that reflecting the system characteristics with the fractal dimension of vibration signals containing noise is not reliable, the measured signals must be denoised prior to calculation of morphology fractal dimension, thus the cylinder liner wear condition can be identified clearly.