TGO非均匀增长对热障涂层应力演化和破坏机理的影响

The cohesive force model and the thermal growth oxide (TGO) non-uniform growth subroutine were used to numerically simulate the stress development and cracking behavior of the thermal barrier coating (TBC) under thermal cycling loading. The cracking process was firstly caused by the mixed Ⅰ and Ⅱ cracks due to the tensile and shear stress in the near peak position in the top coat (TC); it turned to the mode Ⅱ crack due to the shear stress near the peak of the TC and the mode Ⅰ crack due to the tensile stress in the thickness direction in the middle of the peak and trough with the increasing number of thermal cycles. The maximum tensile stress in the overall non-uniform growth and the valley uniform growth mode almost did not increase with the number of cycles after some cycles; while in the peak uniform growth and the overall uniform growth mode, the maximum tensile stress increased continuously. In the global non-uniform growth mode and the valley non-uniform growth mode, the maximum shear stress of -162.41MPa and -154.28MPa appeared at the position near the peak after 20 cycles; while in the global uniform wave growth and global uniform growth mode, the maximum shear stress were -113.82MPa and -111.98MPa, respectively. For the uniform growth of the valley and the overall non-uniform growth mode, interface cracks appeared after 9 cycles; while for the uniform peak growth and overall non-uniform growth mode, interface cracks appeared in the 17th cycle.