Failure characteristics and service life prediction of polycrystalline diamond compact (PDC) cutter under cyclic impact loading

Abstract

This paper aims to investigate the cyclic impact damage characteristics and service life of PDC cutters under varying impact loadings, angles, and depths. Additionally, a life prediction model is established to predict the fatigue life of flat cutters, axe cutters, and triangular cutters. A customized impact test device was utilized to conduct the cyclic impact test, and a finite element model was calibrated based on the experiment result of flat PDC cutter. Then, the model was used to analyze the stress distribution in the axe and triangular cutters, respectively. By combining the experimental and numerical results, the S–N (Stress-Number of times) curve representing the fatigue failure of the PDC cutter substrate was established. Moreover, the fatigue life of different PDC cutters under impact loading was predicted by integrating the S–N curve with the results of finite element stress analysis. The findings indicate that triangular cutters exhibited the longest fatigue life, with a 30.36% increase compared to flat cutters, under an impact angle of 15°, an impact depth of 4 mm, and an impact loading of 7616N. Similarly, the fatigue life of axe cutters was 7.59% higher than that of flat cutters. These findings suggest that non-flat cutters have greater impact resistance and are more suitable for heterogeneous strata characterized by significant impact stress variations.