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http://dx.doi.org/10.3740/MRSK.2014.24.2.87

Development of Stress Intensity Factor Equation for the Notched Ring Test (NRT) Specimen  

Pyo, Sooho (Gas Technology Institute)
Choi, Sunwoong (Department of Polymer Science and Engineering, Hannam University)
Publication Information
Korean Journal of Materials Research / v.24, no.2, 2014 , pp. 87-92 More about this Journal
Abstract
The Notched Ring Test(NRT) has proven to be very useful in determining the slow crack growth behavior of polyethylene pressure pipes. In particular, the test is simple and an order of magnitude shorter in experimental times as compared to the currently used Notched Pipe Test(NPT), which makes this method attractive for use as the accelerated slow crack growth test. In addition, since the NRT specimen is taken directly from the pipe, having maintained the cross-section, processing induced artifacts that would affect the slow crack growth behavior are not altered. This makes the direct comparison to the slow crack growth specimen in pipe from more meaningful. In this study, for comparison with other available slow crack growth methods, including the NPT, the stress intensity factor equation for NRT specimen was developed and demonstrated of its accuracy within 3% of that obtained from the finite element analysis. The equation was derived using a flexure formula of curved beam bending along with numerically determined geometric factors. The accuracy of the equation was successfully tested on 63, 110, 140, 160, 250, and 400 mm nominal pipe diameters, with crack depth ranging from 15 % to 45 % of the pipe wall thickness, and for standard dimensional ratio(SDR) of 9, 11, and 13.6. Using this equation the slow crack results from 110SDR11 NRT specimen were compared to that from the NPT specimen, which demonstrated that the NRT specimen was equivalent to the NPT specimen in creating the slow crack, however in much shorter experimental times.
Keywords
notched ring test(NRT); notched pipe test(NPT); slow crack growth; stress intensity factor; plastics pipes and fittings;
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  • Reference
1 S. H. Beech, J. N. Mallinson, in Proceedings of the Plastics pipes X, Goteborg, Sweden, p.311 (1998).
2 J. Berthold, L. Bohm, H. F. Enderle, V. Lackner, D. Lilge, U. Schulte. in Proceedings of the Plastics Pipes XI, Munich, Germany, p.97 (2001).
3 A. J. Peacock. Handbook of Polyethylene. Marcel Dekker Inc., New York, (2000).
4 P. A. O'Connel, M. J. Bonner, R. A. Dcckett, I. M. Ward, Polym. 36(12), 2355 (1995).   DOI
5 N. Brown, X. Lu, Polym, 36(3), 543 (1995).   DOI
6 ISO TS 16479, International Standard Organization, Geneva, Switzerland, (2012).
7 ISO 13479, International Standard Organization, Geneva, Switzerland, (1997).
8 S. Pyo, J. Nam, Y. Kim and S. Choi, Polym. Test., 30(3), 324 (2011).   DOI
9 M. Backman, in Proceedings of the Plastics Pipes XI, Munich, Germany, p.85 (2001).
10 S. Pyo, C. Tischler, J. Moon, S. Choi, Polym. Test., 29(4), 324 (2010).
11 M. Janssen, J. Zuidema, R. J. H. Wanhill, Fracture mechnics, 2nd ed, Spon Press, Abingdon, (2004).
12 R. D. Henshell, K.G. Shaw, Int. J. Numerical Methods Eng., 9(3), 495 (1975).   DOI   ScienceOn
13 E. E. Gdoutos. Fracture mechanics an introduction, 2nd ed, Spinger, Dordrecht, (2005).
14 W. Young, R. Budynas, A. Sadegh, Roark's Formulas for Stress and Strain, 7th ed. McGraw-Hill, New York, (2002).
15 Barsoum, R. S., Int. J. Numerical Methods Eng., 10(1), 25 (1976).   DOI   ScienceOn
16 S. Choi, S. Pyo, Y. S. Suh and Y. Seo, Plast. Rubber Composites, 36(5), 219 (2007).   DOI
17 L. J. Rose, A. D. Channell, S. J. Palmer. in Proceedings of the Plastics Pipes IX, Edinburgh, Scotland, p.588 (1995).
18 Nussbaum M., in Proceedings of the 9th Plastic Fuel Gas Pipe Symposium, New Orleans, USA, p.263 (1985).
19 ISO 13480, International Standard Organization, Geneva, Switzerland, (1997).