Progressive phase trends in multi-degree-of-freedom systems

The use of dual channel FFT analyzers with their ability to generate phase and amplitude data rapidly and over a broad frequency range has led to a greater awareness of the behavior of phase response curves than has existed at the time before the introduction of such analyzers. Attention is given to the amplitude and phase response of the casing of a Diesel engine due to a pressure pulse within the combustion chamber. The unwrapped phase of the transfer function of the Diesel engine is compared to the propagation phase of a bending wave. The present investigation is concerned with an examination of the behavior of phase in multi-degree-of-freedom (multi-dof) systems to determine the general rules which govern such functions. On the basis of the obtained results it is concluded that in certain circumstances it is possible to find simple rules which imply rather elementary calculations for the determination of the progression of phase with frequency for quite complicated systems.