Working group 3- Identification of non-linear systems

Researchers in structural dynamics have long recognised the importance of diagnosing and
modelling non-linearity. The last 20 years have witnessed a shift in emphasis from single
degree-of-freedom (sdof) to multi-degree-of-freedom (mdof) non-linear structural
dynamics. The main feature of the program of COST F3 Working Group 3 was to
identify the behaviour of a structure which exhibits a localised non-linear component.
Inside this working group, two benchmarks were defined and studied intensively, thereby
allowing to evaluate different identification methods and compare their efficiency and
specificity. For this purpose, a large amount of data (time and frequency measurements)
was collected and proposed to COST F3 participants. The two benchmarks that are
described in the following are:
* The VTT benchmark proposed by M. Juntunen from the VTT Technical Research of
Finland;
* The ECL benchmark proposed by F. Thouverez from the Ecole Centrale de Lyon
(France).
The VTT benchmark is essentially one-dimensional but with a type of non-linearity that is
not known a priori. This is different from the ECL benchmark designed to implement a
cubic stiffness hardening but which address mdof systems. The ECL benchmark was
challenging in the sense that the considered structure is continuous and that several modes
participate in the response.
*Supported by a grant from the Belgian National Fund for Scientific Research.
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