Frequency analysis of a four cylinder diesel engine crankshaft by using finite element method and FFT analyzer
Keywords:
Natural Frequency, Crankshaft, Finite Element Method, Fast Fourier Transform analyzer, Torsional Vibration.Abstract
The scope of the paper is the study of the crankshaft torsional vibration phenomenon in internal combustion
engines. The natural frequencies of torsional vibration of four cylinder diesel engine crankshaft are determined by finite
element method. The natural frequency of a system is important as it is main cause of various types of failures like
resonance of the whirling modes of a crankshaft are suspected to be the cause of excessive bearing noise or fatigue
failure. The high level harmonic forcing torque developed in internal combustion engine can produce large torsional
stress level resulting in early fatigue in crankshaft. Therefore by knowing the natural frequencies and frequency modes of
the engine the limitation in use of the engine working speeds can be fixed. A simultaneous iteration technique is used in
solution of the finite element method. The frequencies obtained by the fast fourier transform (fft) analyzer and those
obtained by fem are found in good agreement.
