Abstract <p>With the aim of revealing the failure process of the thermal barrier coatings (TBCs) during the thermal cycling, a finite element model that incorporated the sintering of ceramic top coat and growth of thermally grown oxides was developed to explore the dynamic propagation behavior of cracks in this study. The results suggested that the propagation of cracks showed a stepwise pattern, in which the cracks rapidly propagated within a very short time once the stress intensity factor reached the fracture toughness of coating. When the coating porosity increased to 15%, the total crack length after 200 thermal cycles was more than twice that observed in the 5% porosity coating, and the number of cracks increased by over seven times. The thermal insulation temperature rose from 109.97 to 137.86 °C, while the thermal cycling lifetime decreased from 193 cycles to 130 cycles. Although the thermal insulation performance improved by only 18.46%, the thermal cycling lifetime was reduced by 48.5%. For a coating with lower porosity, most of cracks propagated from the surface to the interior of coating. However, high-porosity coatings were prone to forming numerous short microcracks during thermal cycling, which easily propagated from the interior to the surface and connected with adjacent pores to form some large and through-thickness cracks, substantially reducing the thermal cycling life of coatings. These findings provided new insights into the dynamic propagation behavior of cracks under thermal cycling conditions and provided a reference for designing high-performance TBCs.</p> Graphical Abstract <p>A finite element model of thermal barrier coatings (TBCs) with varying structures was developed to examine cracking propagation and the impact of structural differences during thermal cycling. The simulation results were validated through experiments, revealing the crack propagation process within the coatings and offering valuable insights for optimizing coating design.</p>