Using J-integral analysis to predict the failure of HDPE pipes under crack face load and internal pressure

Cracks in pipes used for water transfer have been identified as a significant contributor to water loss and potential failures. To assess fracture behavior, the J-integral was computed for 3D finite element HDPE pipes (DN 355) with axial internal and external cracks (with a/c and a/t ratios of 0.5) subjected to a range of internal pressure (16-30 bar) and crack face load condition. Four ratios of a/c ranging from 0.3 to 0.9 (with an increment of 0.2) were examined with the internal crack. Results indicate that under face crack loading, the external axial crack exhibits a higher J-integral intensity than the internal axial crack. J-integral values greater than 8.4 kJ/m(2) were found to lead to pipe failure, with higher internal pressures (25-30 bar for external crack, and 30 bar for internal pressure). Moreover, the a/c ratio plays a significant role in influencing the distribution of J-integral along internal crack arc length. For pipes of DN 355 size with axial cracks, internal pressure exceeding 20 bar is not recommended. These findings underscore the importance of considering J-integral values in pipe design to prevent failure.