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Abstract

Examination of the published procedure for performing calculations on data obtained from the C-ring fracture toughness test for unplasticised poly(vinyl chloride) reveals a major flaw. The dimensions of the specimens do not satisfy the ASTM criteria for plane strain conditions and correction factors are therefore introduced. However, there is an error in the calculation procedure, which results in variations in the severity of the test with pipe wall thickness. An improved approach is proposed and recommendations are made for changing the ISO/DIS 11673·2 test standard, to allow for variations in the yield strength of unplasticised poly(vinyl chloride) and to identify the calculated data as K _c rather than K _1c.

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References

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G. P.

and BIRCH

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: Proc. 5th Int. Conf. on ‘Plastics pipes’, York, UK, September 1982, Plastics and Rubber Institute, paper 19.

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WRc Water Industry Specification no. 4-31-06 Issue 1: Specification for blue unplasticised PVC pressure pipes, integral joints and post-formed bends for cold potable water (underground use), January 1990.

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ASTM D 5045: Standard test methods for plane strain fracture toughness and strain energy release rate of plastic materials.

Improvements to C-ring fracture toughness test for poly(vinyl chloride) pipes

Abstract

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