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

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