Contributions to Proceedings:
R. Heuer, F. Ziegler:
"Vibrations of layered structures with fuzzy core stiffness/fuzzy interlayer slip";
in: "Proc. IUTAM-Symp. on The Vibration Analysis of Structures with Uncertainties",
A. Belyaev et al. (ed.);
issued by: Russian Academy of Sciences;
Mainly the matrix in composite structures exhibits fuzzy randomness of
the material parameters. When extending the work on two and symmetric, three
layer beam-, plate- and shell structures based on the definition of an equivalent
effective homogeneous model, to include either fuzzy interface slip or fuzzy core
stiffness, we can avoid numerical analyses schemes and work out the effects on the
dynamic properties of these fuzzy structures. Fully analyzed within the scope of
this paper is a simply supported sandwich beam with fuzzy core material parameters.
The analysis of this illustrative example is based on the interval representation
(interval of confidence at a given level of presumption, i.e. a-cut) with a triangular
fuzzy membership function of the core shear stiffness prescribed. Fuzzy membership
functions of the natural frequencies are defined using fuzzy set theory, however,
avoiding artificial uncertainties. Under time-harmonic excitation, the dynamic magnification
factors and, with light modal structural damping taken into account, the
fuzzy phase angles of the modal response are evaluated. Thus, modal superposition
of forced vibrations becomes fuzzy in both, the time and the amplitude response.
Where possible, envelope functions are defined.
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