Hybrid Representations of Coupled Nonparametric and Parametric Models for Dynamic Systems

 

Roger Ghanem and Sonjoy Das

AIAA Journal, v 47, No 4, pp. 1035--1044 , 2009, doi: 10.2514/1.39591


Parametric modeling of stochastic systems has proven useful for systems with well-defined and well structured sources of uncertainty. The suitability of such models is usually indicated by small levels of uncertainty associated with their parameters. The parametric model may not be efficiently employed to deal with problems associated with high level of uncertainty particularly due to the modeling uncertainty. The class of so-called nonparametric stochastic models has recently been introduced to address this specific issue and found to be useful to some extent. This paper presents a coupling technique, adapted to the receptance Frequency Response Function (FRF) matrix, that will be useful for analyzing a complex dynamical system, particularly when it consists of several stochastic subsystems each of which is individually deemed suitable for either parametric model or nonparametric model. Such complex dynamical system is otherwise difficult to analyze. The existing nonparametric approach was, till date, applied to the real-valued positive definite/semi-definite random system matrix, for example, mass, damping and stiffness matrices. In the present work, the nonparametric approach is also employed to the complex-valued symmetric receptance FRF matrix, now acting as the system matrix, by having recourse to Takagi's factorization.

 

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