Linearization of supports with gaps in dynamic piping analyses

Aapo Ristaniemi

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

Nuclear power plant piping systems exhibit dynamic behaviour, and piping supports keep the displacements of the pipes within acceptable limits. The aim of the research is the development of a simplified way to take into account the nonlinear displacement behaviour of the supports in linear dynamic piping analyses. The research was started as a Master's thesis with focus on supports with gaps and friction and was further continued regarding supports with gaps. The linearization procedure and methods are found in literature and they were further developed in this study. The goal is to represent the nonlinear system as accurately as possible by an equivalent linear system. The linearization procedure was investigated in time-domain and frequency-domain analyses using simplified piping systems. Frequency-domain is of particular interest as nonlinearities cannot be incorporated into classical mode-based methods. Equivalent linear systems were determined for the selected load cases and comparison was made between the equivalent linear and original nonlinear systems, time-domain and frequency-domain linearization results and three different linearization methods. Correspondence between equivalent linear and original nonlinear systems was not found accurate, time- and frequency-domain linearization gave similar results and different linearization methods resulted in equivalent linear systems very close to each other.
Original languageEnglish
Title of host publicationBaltica X
Subtitle of host publicationInternational Conference on Life Management and Maintenance for Power Plants
EditorsPertti Auerkari
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages13
ISBN (Electronic)978-951-38-8436-9, 978-951-38-8435-2
Publication statusPublished - 2016
MoE publication typeA4 Article in a conference publication
EventBALTICA X - International Conference on Life Management and Maintenance for Power Plants - Cruise, Helsinki-Stockholm, Finland
Duration: 7 Jun 20169 Jun 2016

Publication series

SeriesVTT Technology
Volume261

Conference

ConferenceBALTICA X - International Conference on Life Management and Maintenance for Power Plants
Abbreviated titleBaltica X
CountryFinland
CityHelsinki-Stockholm
Period7/06/169/06/16

Fingerprint

Linearization
Linear systems
Nonlinear systems
Piping systems
Nuclear power plants
Pipe
Friction

Cite this

Ristaniemi, A. (2016). Linearization of supports with gaps in dynamic piping analyses. In P. Auerkari (Ed.), Baltica X: International Conference on Life Management and Maintenance for Power Plants Espoo: VTT Technical Research Centre of Finland. VTT Technology, Vol.. 261
Ristaniemi, Aapo. / Linearization of supports with gaps in dynamic piping analyses. Baltica X: International Conference on Life Management and Maintenance for Power Plants. editor / Pertti Auerkari. Espoo : VTT Technical Research Centre of Finland, 2016. (VTT Technology, Vol. 261).
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Ristaniemi, A 2016, Linearization of supports with gaps in dynamic piping analyses. in P Auerkari (ed.), Baltica X: International Conference on Life Management and Maintenance for Power Plants. VTT Technical Research Centre of Finland, Espoo, VTT Technology, vol. 261, BALTICA X - International Conference on Life Management and Maintenance for Power Plants, Helsinki-Stockholm, Finland, 7/06/16.

Linearization of supports with gaps in dynamic piping analyses. / Ristaniemi, Aapo.

Baltica X: International Conference on Life Management and Maintenance for Power Plants. ed. / Pertti Auerkari. Espoo : VTT Technical Research Centre of Finland, 2016. (VTT Technology, Vol. 261).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

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AU - Ristaniemi, Aapo

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N2 - Nuclear power plant piping systems exhibit dynamic behaviour, and piping supports keep the displacements of the pipes within acceptable limits. The aim of the research is the development of a simplified way to take into account the nonlinear displacement behaviour of the supports in linear dynamic piping analyses. The research was started as a Master's thesis with focus on supports with gaps and friction and was further continued regarding supports with gaps. The linearization procedure and methods are found in literature and they were further developed in this study. The goal is to represent the nonlinear system as accurately as possible by an equivalent linear system. The linearization procedure was investigated in time-domain and frequency-domain analyses using simplified piping systems. Frequency-domain is of particular interest as nonlinearities cannot be incorporated into classical mode-based methods. Equivalent linear systems were determined for the selected load cases and comparison was made between the equivalent linear and original nonlinear systems, time-domain and frequency-domain linearization results and three different linearization methods. Correspondence between equivalent linear and original nonlinear systems was not found accurate, time- and frequency-domain linearization gave similar results and different linearization methods resulted in equivalent linear systems very close to each other.

AB - Nuclear power plant piping systems exhibit dynamic behaviour, and piping supports keep the displacements of the pipes within acceptable limits. The aim of the research is the development of a simplified way to take into account the nonlinear displacement behaviour of the supports in linear dynamic piping analyses. The research was started as a Master's thesis with focus on supports with gaps and friction and was further continued regarding supports with gaps. The linearization procedure and methods are found in literature and they were further developed in this study. The goal is to represent the nonlinear system as accurately as possible by an equivalent linear system. The linearization procedure was investigated in time-domain and frequency-domain analyses using simplified piping systems. Frequency-domain is of particular interest as nonlinearities cannot be incorporated into classical mode-based methods. Equivalent linear systems were determined for the selected load cases and comparison was made between the equivalent linear and original nonlinear systems, time-domain and frequency-domain linearization results and three different linearization methods. Correspondence between equivalent linear and original nonlinear systems was not found accurate, time- and frequency-domain linearization gave similar results and different linearization methods resulted in equivalent linear systems very close to each other.

M3 - Conference article in proceedings

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Ristaniemi A. Linearization of supports with gaps in dynamic piping analyses. In Auerkari P, editor, Baltica X: International Conference on Life Management and Maintenance for Power Plants. Espoo: VTT Technical Research Centre of Finland. 2016. (VTT Technology, Vol. 261).