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Structural Engineering and Mechanics Volume 64, Number 3, November10 2017 , pages 279-285 DOI: https://doi.org/10.12989/sem.2017.64.3.279 |
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Improved block-wise MET for estimating vibration fields from the sensor |
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Byung Kyoo Jung, Weui Bong Jeong and Jinrae Cho
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| Abstract | ||
| Modal expansion technique (MET) is a method to estimate the vibration fields of flexible structures by using eigenmodes of the structure and the signals of sensors. It is the useful method to estimate the vibration fields but has the truncation error since it only uses the limit number of the eigenmodes in the frequency of interest. Even though block-wise MET performed frequency block by block with different valid eigenmodes was developed, it still has the truncation error due to the absence of other eigenmodes. Thus, this paper suggested an improved block-wise modal expansion technique. The technique recovers the truncation errors in one frequency block by utilizing other eigenmodes existed in the other frequency blocks. It was applied for estimating the vibration fields of a cylindrical shell. The estimated results were compared to the vibration fields of the forced vibration analysis by using two indices: the root mean square error and parallelism between two vectors. These indices showed that the estimated vibration fields of the improved block-wise MET more accurately than those of the established METs. Especially, this method was outstanding for frequencies near the natural frequency of the highest eigenmode of each block. In other words, the suggested technique can estimate vibration fields more accurately by recovering the truncation errors of the established METs. | ||
| Key Words | ||
| modal expansion technique; vibration field; truncation error; modal assurance criterion; sensor placement optimization | ||
| Address | ||
| Byung Kyoo Jung and Weui Bong Jeong : School of Mechanical Engineering, Pusan National University, 2, Busan 46241, Republic of Korea Jinrae Cho : Department of Naval Architecture and Ocean Engineering, Hongik University, Sejong 339-710, Korea | ||