IDENTIFICATION OF MULTI-DEGREE-OF-FREEDOM NON-LINEAR SYSTEMS UNDER RANDOM EXCITATIONS BY THE “REVERSE PATH” SPECTRAL METHOD

✍ Scribed by C.M. Richards; R. Singh

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 534 KB
• Volume: 213
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1006/jsvi.1998.1522

✦ Synopsis

Conventional frequency response estimation methods such as the ''H1'' and ''H2'' methods often yield measured frequency response functions which are contaminated by the presence of non-linearities and hence make it difficult to extract underlying linear system properties. To overcome this deficiency, a new spectral approach for identifying multi-degree-of-freedom non-linear systems is introduced which is based on a ''reverse path'' formulation as available in the literature for single-degree-of-freedom non-linear systems. Certain modifications are made in this article for a multi-degree-of-freedom ''reverse path'' formulation that utilizes multiple-input/multiple-output data from non-linear systems when excited by Gaussian random excitations. Conditioned ''Hc1'' and ''Hc2'' frequency response estimates now yield the underlying linear properties without contaminating effects from the non-linearities. Once the conditioned frequency response functions have been estimated, the non-linearities, which are described by analytical functions, are also identified by estimating the coefficients of these functions. Identification of the local or distributed non-linearities which exist at or away from the excitation locations is possible. The new spectral approach is successfully tested on several example systems which include a three-degree-of-freedom system with an asymmetric non-linearity, a three-degree-of-freedom system with distributed non-linearities and a five-degree-of-freedom system with multiple non-linearities and multiple excitations.