Monday  |  Salon 14  |  05:10 PM–05:30 PM

#16560–Extension and Experimental Verification of an Efficient Re-Analysis Method for Modified Nonlinear Structures

Design changes often occur during engineering applications. Although there are numerous methods to implement these changes and efficiently re-calculate dynamic responses for linear systems; methods applicable to nonlinear systems are limited. Considering the cost of re-analysis of large-scale system models, the development of such methods has major importance. An earlier study attempted to re-analyze a modified non-linear system using FRFs of the original system and the properties of the modification and employing a numerically efficient approach, but the method has a highly restricting limitation of modification to be on a single element with ground connection. In later research of the authors of this paper, modification of non-linear systems using modal models has been implemented on systems with multiple, yet local nonlinearities through simulated experiments on lumped spring-mass-damper systems and is shown to estimate the dynamic behavior of the modified system successfully. The study utilized response controlled stepped sine tests to generate quasi-linear FRFs of the original system. Obtaining these quasi-linear FRFs for different vibration amplitudes resulted in the implementation of an efficient re-analysis method which was previously developed for linear systems. It was also shown that full duality between response-controlled and force-controlled FRFs is possible. The current study is an extension of the aforementioned study to a wider range of non-linearity types of the original system. Also, in this study, the severity of modification on the linear elements of the system is increased both in terms of modification level and in terms of the number of affected coordinates which resulted in a significant shift in the natural frequency of the original system. Both the simulated and real experiments performed in this study showed that the modified system response can be estimated with high numerical efficiency and accuracy even at significantly high modification levels affecting several of the linear elements of the original system.

E. Ceren Ekinci   Middle East Technical University
Taylan Karaağaçlı   The Scientific & Technological Research Council of Turkey
Furkan Kaan Çelik   The Scientific & Technological Research Council of Turkey
M. Bülent Özer   Middle East Technical University
H. Nevzat Özgüven   Middle East Technical University