Root Cause Analysis of the Principal Underlying Factors Contributing to CIPP Flexural Data Variation

摘要

The determination of the flexural modulus and strength of a CIPP field sample is the standard test used torndetermine the short term physical properties of a CIPP installation. In our 2010 paper “Factors Affecting the Qualityrnof Flexural Properties” we demonstrated with experimental data, the significant variability present in flexural datarndetermined using the existing CIPP standard methods. While we identified the factors and the extent to which theyrnaffect flexural test data, we did not determine the underlying causes. Test variability makes it difficult for ownersrnand installers to confidently use flexural test data to confirm contract compliance.rnThis paper closes the book on our original 2010 paper by determining the specific root causes of the factorsrnwe originally defined. Using the results of further experiments as well as theoretical and numerical analyses of testrnspecimen geometry and stress distribution, test deflection artifacts and the effect of through thickness degree of cure,rnwe successfully define the underlying reasons for this flexural testing data variation. The paper also describes thernspecific test specimen preparation and testing techniques which should be implemented to reduce this variability.