Fatigue integrity analysis of a howitzer cannon by using a fracture mechanics approach

Abstract

This study focuses on analysing the integrity and fatigue life of a cannon barrel manufacturedfrom the KATO1 alloy (35NiCrMoV12-5) using two different heat treatments. The analysis utilizesa fracture mechanics approach, primarily based on the concept of a fatigue resistance curve. Toconduct the analysis, various essential variables were either experimentally measured or theoreticallyestimated. These variables include microstructural size, static strength, fracture toughness,fatigue threshold for long crack growth, short crack range, fatigue crack propagationproperties and fatigue limit. The fatigue limits of both materials were determined experimentallythrough the thermographic method.The approach employed in this study has proven effective in quantifying the influence of thesedifferent variables on the fatigue resistance and overall life of the barrel, as well as its safeoperating conditions. By considering these factors, it becomes possible to define a safe domain forthe utilization of the cannon barrel and estimate the fatigue life under unsafe conditions.Furthermore, the analysis has provided valuable insights into areas where improvements canbe made to enhance the fatigue resistance of the barrel material. Notably, addressing the fatiguethreshold for long cracks could yield significant benefits by increasing the critical crack length fora given maximum pressure. This improvement would enhance the durability of the barrel,ensuring better performance over an extended period of use.