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[Display omitted] • Interfacial debonding of a porous TBC system is studied via SEM image-based FE analysis. • Microstructural pores of SEM image of TBC sample are imported into FE software via CMM. • Pores of TC force the stress to be concentrated adjacent to rough TC/TGO interface and develop TC/TGO interface damage. • Porosity within the BC diminishes stress and damage values along the TGO/BC interface. • Creep leads to stress relaxation of TC up to 24.82 % and lowers the damage level of TGO/BC interface. Numerical analysis of interfacial delamination and the effect of microstructural pores and rough interfaces on the field variables in thermal barrier coatings (TBCs) based on a real scanning electron microscope (SEM) image is performed. The interfacial delamination is modelled by the utilization of cohesive zone method (CZM) in finite element (FE) analysis. The empirical TBC sample considered in this study is constructed via air plasma spray (APS) method and comprises ZrO 2 7 - 8 wt. % Y 2 O 3 ceramic top coat (TC), thermally grown oxide (TGO) made of Al 2 O 3 and NiCrAlY metallic bond coat (BC). A compatible geometry is provided by applying image processing technique to SEM image of the sample's cross-section. SEM image-based geometry imported into FE software to scrutinize the interplay effects of porosity and rough interfaces on temperature fields, thermal stresses and interfacial debonding of TC/TGO and TGO/BC interfaces of the TBC structure. FE analysis reveal that porosity distribution has a prominent role on the stress concentration zones at the sharp corners of pores especially adjacent to undulations of the TC/TGO interface, which is responsible for possible internal cracks and interfacial fracture, respectively. The main findings demonstrate that the porosity near the TC/TGO interface has detrimental effect as leads to aggravation in the TC/TGO interface damage, which causes an increment in TC/TGO interfacial crack length. While, the porosity within the BC has the ability to reduce the stress and damage level along the TGO/BC interface. In addition, considering creep for all layers leads to lower stress levels up to 24.82 % and consequently alleviates the TC/TGO interface damage. [ABSTRACT FROM AUTHOR]

• The interface crack between two dissimilar quasicrystal materials. • The gradient theory of thermoelasticity for quasicrystals. • The gradient theory for heat conduction problem. • Decagonal quasicrystal properties. • The mixed FEM formulation with C0 continuous finite elements for independent approximations of displacements and strains. The interface crack problem between two dissimilar materials under a thermal load is analyzed by the gradient elasticity theory since the size effect is expected in the very thin quasicrystal layer. The uncoupled thermoelasticity is considered here, where the thermal fields are independent on mechanical ones. The thermal transport can't be well described by classical Fourier's law in nano-sized structures. Therefore, a novel gradient theory is developed in such structures, where the second derivatives of temperature in the constitutive equation for the high-order heat flux are considered. Moreover, the phonon strain gradients are incorporated into the higher-grade continuum model. Decagonal quasicrystal material properties are considered here. Governing equations and corresponding boundary conditions are derived from the principle of virtual work. The mixed finite element method (MFEM) is developed for a general 2D boundary value problem. Numerical examples are presented to illustrate the phonon, phason and thermal response to external thermal loading within the considered model. [ABSTRACT FROM AUTHOR]