Finite element study of multi-modal vibration damping for thermal barrier coating applications

A physically-based computational model is developed to predict the damping behavior of oxide thermal barrier coating systems. The constitutive damping model is derived from the theory of point defect relaxation in crystalline solids and implemented within a finite element framework. While oxide coatings have been primarily employed as thermal barriers for gas turbine blades, there is a growing interest in developing multifunctional coatings combining thermal protection and damping capabilities. The direct frequency response method, as well as the modal strain energy method, have been implemented to evaluate the functional dependance of damping on temperature and frequency. Numerical results are validated through the limited experimental data available in the literature, and new results are presented to illustrate the effects of different topcoat oxides. The paper also illustrates how the developed methodology enables the damping capacity under different vibrational modes to be predicted, and to estimate the sensitivity of the design for varying geometrical parameters. Finally, the computational model is applied to investigate the damping performance of an oxide-coated turbine blade.