## 3pSA3. Experimental identification of fuzzy structure parameters.

### Session: Wednesday Afternoon, May 15

### Time: 1:00

**Author: Raymond J. Nagem**

**Author: Ann W. Stokes**

**Author: Allan D. Pierce**

**Location: Dept. of Aerospace and Mech. Eng., Boston, Univ., 110 Cummington St., Boston, MA 02215**

**Abstract:**

Researchers have recently been developing a theory to model structures in
which a primary or ``master'' structure with precisely known parameters is
coupled to ``fuzzy'' substructures with parameters known only in a statistical
sense. The goal of the fuzzy theory is to model complex structures with as few
parameters as possible. The research presented here is an experimental
investigation of the effectiveness of fuzzy parameter choices in modeling the
drive-point impedance of a beam with a number of simple oscillators attached
along its length. The fuzzy model makes use of ``most likely'' distributions of
mass per unit resonance frequency, given limited knowledge about the attached
oscillators. The oscillators are interchanged in order to achieve various
realizations of mass per unit natural frequency. The magnitude and phase of the
measured drive point impedance are compared to that predicted by fuzzy theory
models. The use of the moments of the mass per unit natural frequency
distribution as the primary descriptors of the effect of the fuzzy substructures
is examined. Bounds on the differences between predicted and measured drive
point impedances are established. The use of these bounds in applications such
as high-performance, robust vibration control is discussed.

from ASA 131st Meeting, Indianapolis, May 1996