### Abstract

Excessive vibration is one of the leading causes of high
cycle fatigue in process piping. One way to assess the
severity of vibration is to measure the stress variation
caused by it with strain gages. An alternative way is
discussed in this paper. The basis of this alternative
way is formed by operational displacement shapes (ODS)
measured from the actual structure. In order to test the
method, two different sets of ODS were measured from a
secondary feed water piping system of Loviisa 1 nuclear
power plant. Two sets of forces were then derived from
these two measured ODS sets. Each force set is supposed
to be equivalent to the actual loading in a sense that it
should produce behaviour analogous to the actual measured
ODS when applied to a finite element (FE) model. Two sets
of ODS were then computed with the FE model using the
derived force sets as input values. As a result, two sets
of stress amplitudes were also obtained for the ODS.
Vibration borne stress variations in the time domain at
the desired locations were then estimated by applying the
principle of superposition to the stress variation
amplitudes of the individual ODS.

Original language | English |
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Title of host publication | Proceedings of the IMAC-XXVI: A conference & Exposition on Structral Synamics. Orlando, Florida, USA, 4 - 7 Feb. 2008 |

Pages | 2333-2346 |

Volume | 4 |

Publication status | Published - 2008 |

MoE publication type | A4 Article in a conference publication |

Event | 26th IMAC Conference and Exposition on Structural Dynamics 2008 IMAC XXVI - Orlando, Florida, United States Duration: 4 Feb 2008 → 7 Feb 3008 |

### Conference

Conference | 26th IMAC Conference and Exposition on Structural Dynamics 2008 IMAC XXVI |
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Abbreviated title | IMAC XXVI |

Country | United States |

City | Orlando, Florida |

Period | 4/02/08 → 7/02/08 |

### Keywords

- piping vibration
- high cycle fatigue
- finite element

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## Cite this

Vepsä, A. (2008). Operational displacement shape based estimation of vibration borne stress variation in a pipeline. In

*Proceedings of the IMAC-XXVI: A conference & Exposition on Structral Synamics. Orlando, Florida, USA, 4 - 7 Feb. 2008*(Vol. 4, pp. 2333-2346)