Exploration of nonideal effects in a beam model of a fuzzy structure

The presentation that preceded this one analyzed a model of a fuzzy structure as a beam with multiple suspended SDOFs. It examined the degree to which phenomena encountered in a model of the master as a rigid body are replicated when the base displacements of the attachments are unequal. The conclusion was that many response features are replicated in the frequency domain, whereas contributions of higher structure modes cause time domain responses to differ. The present paper examines whether the numerous idealizations that led to that conclusion are crucial. Parameters that are examined are tuning and bandwidth of the fixed base SDOF frequencies, and randomness of the spectral and spatial distribution of the fixed base SDOF natural frequencies. Responses extracted from an “exact” state space solution of the equations of motion show that minor randomness can significantly alter, and sometimes obscure, the phenomena observed in the ideal case. The results bring to the fore the question of whether phenomena observed in idealized fuzzy models are relevant to actual structures.