Towards a new methodology for measuring the macroscopic Young’s modulus of multilayer thin films using Impulse Excitation Technique
Résumé
This work presents an enhanced approach to determine the Young’s modulus of multilayer composite beam using Impulse Excitation Technique (IET). In this technique, the beam is excited and the corresponding natural frequencies are recorded. The Young’s modulus of each individual coating was obtained using different analytical models in the literature and the measured frequencies. Some of the models are limited to a certain film thickness and some others are limited to one-layer coatings. For the purpose to cover all the applicable range of coating’s thickness and for multi-coated beam, one-dimensional model was developed based on the flexural theory. A finite element model is developed and used, as a reference, to validate the proposed model. The proposed relation takes into account the shift of the neutral axis after deposition, which makes it applicable for any film thickness. After validation, the model is applied to determine the macroscopic Young’s modulus of niobium and titanium films deposited on AISI 316 and glass substrates by conventional magnetron sputtering.