Finite element modeling of the elastic modulus of thermal barrier coatings

Effective properties of thermal barrier coatings (TBCs) may be quantified via different measurement techniques. Numerical methods based on image analysis represents an alternative method for predicting these properties. In the present work, the elastic modulus of plasma sprayed Y-PSZ coatings was first estimated by using a 2D mesh formed by SEM cross-sectional images, and then by a 3D finite-element model developed from an artificial 3D coating image. A resolution-adapted mesh was generated for both structures so as to economize the computational resources. Free, symmetric and periodic boundary conditions (BCs) were applied. The constraint BCs may lead to a little higher computed modulus than the free BC does, especially for 2D modeling.The choice of an adequate threshold, allowing the generation of a binary image from a grey-scaled SEM image, was investigated in terms of porosity and computed modulus. It is found that a higher threshold results in a higher porosity level and a lower computed modulus. Then, the effective elastic modulus computed for the 3D image was compared with those obtained from 2D computations performed on cross-sections of this 3D image, revealing the differences between 2D and 3D image-based analyses. Finally, a bending test was implemented to validate the modeling results.