ABSTRACT
In one way or another, at least in principle, almost every vibrating system could be modelled, represented and analysed as a single degree of freedom (SDOF) system. In general, the quality of this assumption depends on the type of system and excitation, on the accuracy required and on the scope of the investigation. In some circumstances the assumption is correct; in some other cases it may lead to an acceptable – that is, within the desired degree of accuracy – description of the system’s behaviour, but in many other cases it is just an extreme oversimplication leading to inaccurate and practically useless results. Since, a priori, the true behaviour of a real system is, in general, not known, the assessment of the quality of the results obtained from an SDOF analysis may not be an easy task. Therefore, in order to obtain a meaningful description for a wide class of systems, more complex representations are needed from the outset.
