Multiaxial fatigue of water pipe grey cast iron

Grey Cast Iron (GCI) water pipes are subjected to multiaxial, cyclic stresses caused by combinations of loads such as internal water pressure and road vehicle weight. However, the multiaxial fatigue performance of this material has not previously been characterised. To address this gap more than 45 fatigue tests, including some under non-proportional tension-torsion loading, were completed using a GCI material very similar to water pipe GCI. Of the four multiaxial fatigue criteria tested, the Smith-Watson-Topper (SWT) criterion provided the best predictions by a narrow margin, supporting the idea that a tensile cracking mode dominates the fatigue life of GCI.