Study on high temperature creep mechanical properties of nickel-based single crystal double-wall cooling structure with different wall thickness ratios

To investigate the strength of the new double-wall cooling structure, three types of double-wall structure specimens with different wall thickness ratios were designed in this study. The creep properties and fracture mechanisms were analyzed through high-temperature creep experiments and finite element calculations based on crystal plasticity theory. The results show that structures with higher wall thickness ratios exhibit smaller deformation and shorter creep life. Under high-temperature creep conditions, stress concentration and local plastic deformation around the inner and outer wall holes are key factors for crack initiation. The uneven wall thickness leads to a non-uniform distribution of stress and deformation, particularly around the inclined hole in the outer wall, where cracks initiate and propagate first. This results in the outer wall fracturing initially, followed by a rapid fracture of the inner wall due to the stress surge, ultimately leading to overall failure. As the wall thickness ratio increases, the evolution of stress and creep damage around the hole accelerates. This study reveals the failure mechanism of double-wall structures under high-temperature creep, providing an important reference for the design and optimization of turbine blade cooling structures.