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.
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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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Mikula, J. et al. (2017). Influence of Different Welding Conditions of Polyolefin Pipes on Creep Crack Growth. In: Grellmann, W., Langer, B. (eds) Deformation and Fracture Behaviour of Polymer Materials. Springer Series in Materials Science, vol 247. Springer, Cham. https://doi.org/10.1007/978-3-319-41879-7_16
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DOI: https://doi.org/10.1007/978-3-319-41879-7_16
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