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Influence of Different Welding Conditions of Polyolefin Pipes on Creep Crack Growth

  • J. Mikula
  • P. Hutař
  • M. Ševčík
  • E. Nezbedová
  • R. Lach
  • W. Grellmann
  • L. Náhlík
Chapter
Part of the Springer Series in Materials Science book series (SSMATERIALS, volume 247)

Abstract

The main aim of the paper is to study the influence of both material inhomogeneity and weld bead geometry on crack propagation in welded polyolefin pipes. Lifetime of three pipes welded by different welding procedures is numerically estimated. Experimentally observed shapes of weld bead and change of material properties inside the welded region (the change of Young’s modulus) is implemented into the numerical model of welded pipes. Circumferential crack is of interest during the crack propagation through the pipe wall and the stress intensity factor is evaluated. It is shown that the deformation of welded region plays an important role whatever it is caused by, either the inhomogeneous distribution of Young’s modulus or the amount of material in that region. The change of weld bead notch radius is not proved to be important for slow crack growth. It is shown that non-optimal welds can significantly decrease lifetime of pipe systems. The results of this research can be used for lifetime estimation and prediction of creep crack growth and further optimisation of welding conditions and butt weld technology.

Notes

Acknowledgements

This research was supported by German Research Foundation (DFG) by grant No. GR 1141/30-1, 31-1 and 32-1. Research team was also supported by the Ministry of Education, Youth and Sports of the Czech Republic throughout the project No. CZ.1.07/2.3.00/30.0063 “Talented postdocs for scientific excellence in physics of materials” and by CEITEC—Central European Institute of Technology with research infrastructure supported by the project CZ.1.05/1.1.00/02.0068 financed from European Regional Development Fund.

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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • J. Mikula
    • 1
    • 2
  • P. Hutař
    • 1
  • M. Ševčík
    • 1
  • E. Nezbedová
    • 3
  • R. Lach
    • 4
  • W. Grellmann
    • 4
    • 5
  • L. Náhlík
    • 1
  1. 1.Institute of Physics of MaterialsAcademy of Sciences of the Czech RepublicBrnoCzech Republic
  2. 2.Brno University of TechnologyBrnoCzech Republic
  3. 3.Polymer Institute BrnoBrnoCzech Republic
  4. 4.Polymer Service GmbH Merseburg, Associated An-Institute of University of Applied Sciences MerseburgMerseburgGermany
  5. 5.Centre of EngineeringMartin Luther University Halle-WittenbergHalle/SaaleGermany

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