Application of fuzzy structures analysis to aircraft panels

In 2000 a research implementation of Christian Soize’s fuzzy structures analysis procedures were implemented by Sparrow in the commercial finite element program MSC/NASTRAN [MSC Software Corp. (Los Angeles, CA)] using its direct matrix abstraction program (DMAP) capability coupled with MATLAB [Mathworks, Inc. (Natick, MA)]. The background and implementation details of the new DMAP code were recently given [AIAA paper 2001–1320, Non‐Deterministic Approaches Forum, 42nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conf., Seattle, WA, 2001]. The present talk will describe the application of the new code to two prototypical aircraft panels: a small 0.96 by 0.19 m panel with one longitudinal stringer and a larger 1.8 by 1.2 m panel including six longitudinal stringers and four equally spaced frame stiffeners. The smaller and larger panels were modeled in NASTRAN as having approximately 7900 and 60<th>000 degrees of freedom, respectively. In these studies the attachment points between the stringers and skin were assumed to be fuzzy. Results will be described comparing the fuzzy and nonfuzzy finite element predictions to experimental vibration results. [Work supported by NASA Research Cooperative Agreement NCC‐1‐382.]