Synergetic effect of coating properties and fibrous architecture on stress evolution in plain-woven ceramic matrix composites

In this work, the synergetic effect of coating properties and fibrous architecture on the evolution of thermal stress was studied by finite element simulation. The numerical implementation was conducted on the plain-woven ceramic matrix composites coated with environmental barrier coatings (EBCs). Within the simulations, the microstructure of both coating layer and composite substrate was precisely modeled. The distributions of thermal residual stress of different yarn waviness and layer properties were simulated and compared. Their synergetic effect on the evolution of stress was then investigated by comparing the simulated results under different mechanical loadings which can enlarge the nonuniform distribution of stress induced by fibrous architecture. The results show that the cooling process causes considerable thermal residual stress in each layer of a Si/mullite/Yb2Si2O7 EBCs. Similar to the layer properties of coatings, the fibrous architecture of the composite substrate also plays an important role in the stress distribution in the coatings. Thus, it can be concluded that an adequate prediction of the local stress distribution and the failure modes for the EBCs requires a realistic representation of fibrous architecture as well as the coating layers. The former is usually ignored in the previous studies.