Internal combustion engine vibration analysis with short-term Fourier-transform

The short-term Fourier-transform (STFT) is used to identify different vibration sources of internal combustion engine vibration signals from valve cover, cylinder head and cylinder block. Interest is focused on using the STFT to distinguish normal combustion from other sources of excitation including valve impact, and piston slap. The influence of the combustion process is considered with the vibration measurements under the motored condition. It shows that the engine vibration is typical non-stationary motion and the time-frequency method is significant to reveal the temporal localization of the signal´s spectral components and to predict the engine physical phenomena. The engine events can be easily identified with STFT.