Experimental Modal Analysis of Structures with High Nonlinear Damping by Using Response-Controlled Stepped-Sine Testing

Date

2024-01-01

Author

Karaağaçlı, Taylan
Özgüven, Hasan Nevzat

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In the last decade, various promising nonlinear modal identification techniques have been developed based on the nonlinear normal mode (NNM) concept. Most of these techniques rely on the phase resonance testing approach where the identification of nonlinear modal damping is still an unresolved issue. The response-controlled stepped-sine testing (RCT) framework provides a convenient way of accurately quantifying nonlinear modal damping by applying standard linear modal analysis techniques to frequency response functions (FRFs) measured at constant displacement amplitude levels with standard modal test equipment. Various studies by the authors have shown that these constant-response FRFs come out in quasi-linear form even in the case of a high degree of nonlinearities. The RCT approach has been validated so far on several systems including a real missile structure with moderate damping nonlinearity mostly due to bolted connections and a micro-electromechanical device with a stack-type piezo-actuator. This study makes a step further by validating the method on a real control fin actuation mechanism that exhibits very high and nonlinear modal damping; the maximum value of viscous modal damping ratio goes up to 15% and the percentage change of the damping with respect to vibration amplitude is about 70%.

Subject Keywords

Control fin actuation mechanism, High nonlinear damping, Nonlinear experimental modal analysis, Response-controlled stepped-sine testing, Unstable branch

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https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85175983969&origin=inward
https://hdl.handle.net/11511/108034

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Department of Mechanical Engineering, Conference / Seminar