Interaction integral method for computation of crack parameters K–T – A review

Thermal barrier coatings (TBCs) are protective coating systems that are mostly utilized to improve the thermal insulation and functional performance of gas turbine engines and other aircraft components that are both stable and movable. These coatings protect materials operating in harsh conditions from structural damage caused by corrosion, oxidation, the CaO-MgO-Al 2 O 3 -SiO 2 effect (CMAS), thermal shock , volcanic ash, and vermiculite deposits at high temperatures. In this study, CoNiCrAIY metallic bond coatings were coated on Inconel 718 super alloy using a high velocity oxygen-fuel (HVOF) deposition technique. Then, single YSZ, Gd 2 Zr 2 O 7 (GZ), and double YSZ/GZ based ceramic topcoats were applied to the bond coats by using the electron beam physical vapor deposition (EB-PVD) method. The produced TBC samples and the uncoated Inconel 718 superalloy substrate were subjected to vermiculite (VM) deposition at 1250 °C for 4 h, and then the coatings were characterized. To determine the phase structures, microstructural and mechanical properties of the TBCs, X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer elemental mapping analysis (EDS), stereo microscopy analyses, porosity, and hardness measurements were used. The obtained results were comparatively evaluated with the recent related studies in the literature. • The aim of this study is to investigate the VM behavior of innovative single- and double-layer TBC systems. • The VM infiltration has occurred through the surface of the Inconel 718 superalloy substrate and all other TBC systems. • HVOF-bond coating and EB-PVD GZ coating were used for deposition of the TBCs. • On the Inconel 718 super alloy surface, YSZ, Gd 2 Zr 2 O 7 , and YSZ/Gd 2 Zr 2 O 7 coatings were deposited. • The TBC systems' initial porosity percentages decreased, but the top coating hardnesses increased. • The TGO structure formed at the interface with the effect of high temperature. 

Investigation of vermiculite infiltration effect on microstructural properties of thermal barrier coatings (TBCs) produced by electron beam physical vapor deposition method (EB-PVD)

Quantitative relationships between the mineral composition and macro mechanical behaviors of granite under different temperatures: Insights from mesostructure-based DEM investigations

Fatigue crack propagation simulation method using XFEM with variable-node element

Study on transient heat flux intensity factor with interaction integral

An interaction integral method for calculating heat flux intensity factor with the XFEM

The finite element (FE) model is established based on the microstructure of the double-ceramic-layer thermal barrier coating system (DCL-TBCs). Different structural parameters are sampled by Latin hypercube Sampling method to construct corresponding models. The energy release rates of the interfacial crack, which is between lanthanum zirconate (LZ) layer and yttria-partially stabilized zirconia (YSZ) layer of DCL-TBCs, are calculated by numerical simulation during cooling and a dataset is created according to the results. On the basis of the dataset, a surrogate model is constructed to predict the maximum energy release rate during cooling by the extreme random forest algorithm, and the prediction accuracy of the surrogate model is verified by testing dataset. The thicknesses and porosities of the LZ and YSZ layers of DCL-TBCs, and the length of the interfacial crack are set as input variables, and the maximum energy release rate during cooling process is set as output variables of the surrogate model. Using the surrogate model and the particle swarm optimization (PSO) method, the LZ and YSZ layers with different combination of thicknesses is optimized to minimize the energy release rate of the interfacial crack of DCL-TBCs. 

Huachao Deng

Papers

Fatigue crack propagation simulation method using XFEM with variable-node element

An interaction integral method for calculating heat flux intensity factor with the XFEM

Surrogate model for energy release rate and structure optimization of double-ceramic-layers thermal barrier coatings system

Study on transient heat flux intensity factor with interaction integral

A new path-independent interaction integral for dynamic stress intensity factors of cracked structures