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FE-modelling of flexible pipes in aftertreatment system for trucks and buses
KTH, School of Engineering Sciences (SCI).
2024 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Exhaust flexible pipes are components characterised by a complex dynamic behaviour.Friction is generated by internal contacts in the interlock and entails adynamic softening phenomenon as the excitation amplitude increases.Due to their complex geometry, the modelling is complicated. The purpose of thethesis is to improve the dynamic model by investigating different Finite Elementformulations. Shell, connector, and thin-walled pipe elements are implemented inAbaqus, and numerical modal analysis is run.The models are adjusted in order to fit the first two experimental eigenfrequenciesidentified by running frequency sweeps in shaker tests. Depending on the method,either manual or automatic parametric optimization in Heeds is performed.The results from different models are compared among themselves and in relation tothe measurements, and their corresponding pros and cons are stated.Since the pipe elements turn out to be the most efficient and applicable way of modellingfor the first case-study of an U-shaped bellow, the method is adopted for othersingle components and a dual bellow assembly as validation.The model succeeds in fitting the eigenfrequencies for another bellow and its implementationin the complete pipe-assembly allows for coherent results with experimentaltests. The match is not reached for a welded flexible hose.New measurements on the shaker table are performed with the aim of capturing thedynamic behaviour of flexible hose, but different results are obtained by using differentways of attaching the accelerometer. The comparison between frequency sweepsat different constant acceleration amplitudes evidences a softening phenomenon dueto non-linear behaviour, which strongly affects the response of the component.

Place, publisher, year, edition, pages
2024.
Series
TRITA-SCI-GRU ; 2025-020
Keywords [en]
Exhaust flexible pipes, Finite Element Method, Modal Analysis, Equivalent thin-walled pipe elements, Shaker test, Non-linear dynamics
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-360292OAI: oai:DiVA.org:kth-360292DiVA, id: diva2:1939730
External cooperation
Scania CV AB
Subject / course
Solid Mechanics
Educational program
Master of Science - Engineering Mechanics
Supervisors
Examiners
Available from: 2025-02-24 Created: 2025-02-24 Last updated: 2025-02-24Bibliographically approved

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CiteExportLink to record
Permanent link

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Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf