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Identification of weak nonlinearities in MDOF systems based on reconstructed constant response tests

Genbei Zhang, Chaoping Zang, Michael Friswell

Archive of Applied Mechanics

Swansea University Author: Michael Friswell

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DOI (Published version): 10.1007/s00419-019-01559-4

Abstract

A novel strategy to characterize and identify structural nonlinearities in MDOF systems based on reconstructing constant response tests from constant excitation tests is developed in this paper. Constant displacement frequency response functions (FRFs) can be measured by a stepped sine test where th...

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Published in: Archive of Applied Mechanics
ISSN: 0939-1533 1432-0681
Published: 2019
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URI: https://cronfa.swan.ac.uk/Record/cronfa50642
first_indexed 2019-06-05T11:08:04Z
last_indexed 2019-06-24T20:53:16Z
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recordtype SURis
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spelling 2019-06-24T14:02:15.6518182 v2 50642 2019-06-05 Identification of weak nonlinearities in MDOF systems based on reconstructed constant response tests 5894777b8f9c6e64bde3568d68078d40 Michael Friswell Michael Friswell true false 2019-06-05 A novel strategy to characterize and identify structural nonlinearities in MDOF systems based on reconstructing constant response tests from constant excitation tests is developed in this paper. Constant displacement frequency response functions (FRFs) can be measured by a stepped sine test where the displacement is controlled at every frequency of interest. In these FRFs, the nonlinear restoring force is effectively linearized and natural frequencies can be estimated by linear modal analysis. Using a series of constant displacement tests, the relationship of equivalent stiffness versus displacement can be established by curve fitting, and hence, the nonlinear stiffness characterized. This paper proposes a method to reconstruct the constant displacement FRFs from stepped sine tests with constant excitation; this avoids the requirement to control either the response or force amplitude leads to a faster and more stable testing program. Similarly, damping nonlinearities in structures can be characterized and identified by constant velocity tests reconstructed in a similar way. This approach of FRF reconstruction is mathematically simple and suitable for structures with weak nonlinearities. The method is demonstrated on a framed structure with unknown weak nonlinearities, and the nonlinear stiffness and damping parameters of the structure are identified and validated. The results demonstrate the feasibility and effectiveness of the approach and also show the potential for practical applications in engineering. Journal Article Archive of Applied Mechanics 0939-1533 1432-0681 Identification, Weak nonlinearity, MDOF, Constructed constant response tests 31 12 2019 2019-12-31 10.1007/s00419-019-01559-4 COLLEGE NANME COLLEGE CODE Swansea University 2019-06-24T14:02:15.6518182 2019-06-05T09:22:53.0413610 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised Genbei Zhang 1 Chaoping Zang 2 Michael Friswell 3 0050642-24062019140146.pdf zhang2019(6).pdf 2019-06-24T14:01:46.8270000 Output 26321625 application/pdf Accepted Manuscript true 2020-05-18T00:00:00.0000000 false eng
title Identification of weak nonlinearities in MDOF systems based on reconstructed constant response tests
spellingShingle Identification of weak nonlinearities in MDOF systems based on reconstructed constant response tests
Michael Friswell
title_short Identification of weak nonlinearities in MDOF systems based on reconstructed constant response tests
title_full Identification of weak nonlinearities in MDOF systems based on reconstructed constant response tests
title_fullStr Identification of weak nonlinearities in MDOF systems based on reconstructed constant response tests
title_full_unstemmed Identification of weak nonlinearities in MDOF systems based on reconstructed constant response tests
title_sort Identification of weak nonlinearities in MDOF systems based on reconstructed constant response tests
author_id_str_mv 5894777b8f9c6e64bde3568d68078d40
author_id_fullname_str_mv 5894777b8f9c6e64bde3568d68078d40_***_Michael Friswell
author Michael Friswell
author2 Genbei Zhang
Chaoping Zang
Michael Friswell
format Journal article
container_title Archive of Applied Mechanics
publishDate 2019
institution Swansea University
issn 0939-1533
1432-0681
doi_str_mv 10.1007/s00419-019-01559-4
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 1
active_str 0
description A novel strategy to characterize and identify structural nonlinearities in MDOF systems based on reconstructing constant response tests from constant excitation tests is developed in this paper. Constant displacement frequency response functions (FRFs) can be measured by a stepped sine test where the displacement is controlled at every frequency of interest. In these FRFs, the nonlinear restoring force is effectively linearized and natural frequencies can be estimated by linear modal analysis. Using a series of constant displacement tests, the relationship of equivalent stiffness versus displacement can be established by curve fitting, and hence, the nonlinear stiffness characterized. This paper proposes a method to reconstruct the constant displacement FRFs from stepped sine tests with constant excitation; this avoids the requirement to control either the response or force amplitude leads to a faster and more stable testing program. Similarly, damping nonlinearities in structures can be characterized and identified by constant velocity tests reconstructed in a similar way. This approach of FRF reconstruction is mathematically simple and suitable for structures with weak nonlinearities. The method is demonstrated on a framed structure with unknown weak nonlinearities, and the nonlinear stiffness and damping parameters of the structure are identified and validated. The results demonstrate the feasibility and effectiveness of the approach and also show the potential for practical applications in engineering.
published_date 2019-12-31T04:48:20Z
_version_ 1821379553908490240
score 11.04748

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