Title
Determination of Elasticity Constants of Isotropic Thin Films Using Impulse Excitation Technique
In
19th International Conference on Experimental Mechanics and Applications, Madrid-Spain, 26-27 March 2017.
Volume
4
Issue
3
Pages
734
Publisher
World Academy of Science, Engineering and Technology - International Journal of Aerospace and Mechanical Engineering
Year
2017
Indexed by

Abstract
Thin films are widely used in various applications to enhance the surface properties and characteristics of
materials. They are used in many domains such as: biomedical, automotive, aeronautics, military, electronics and energy.
Depending on the elaboration technique, the elastic behavior of thin films may be different from this of bulk materials. This
dependence on the elaboration techniques and their parameters makes the control of the elasticity constants of coated
components necessary. Our work is focused on the characterization of the elasticity constants of isotropic thin films by means
of Impulse Excitation Techniques. The tests rely on the measurement of the sample resonance frequency before and after
deposition. In this work, a finite element model was performed with ABAQUS software. This model was then compared with the
analytical approaches used to determine the Young’s and shear moduli. The best model to determine the film Young’s modulus
was identified and a relation allowing the determination of the shear modulus of thin films of any thickness was developed. In
order to confirm the model experimentally, Tungsten films were deposited on glass substrates by DC magnetron sputtering of a
99.99% purity tungsten target. The choice of tungsten was done because it is well known that its elastic behavior at crystal
scale is ideally isotropic. The macroscopic elasticity constants, Young’s and shear moduli and Poisson’s ratio of the deposited
film were determined by means of Impulse Excitation Technique. The Young’s modulus obtained from IET was compared with
measurements by the nano-indentation technique. We did not observe any significant difference and the value is in accordance
with the one reported in the literature. This work presents a new methodology on the determination of the elasticity constants
of thin films using Impulse Excitation Technique. A formulation allowing the determination of the shear modulus of a coating,
whatever the thickness, was developed and used to determine the macroscopic elasticity constants of tungsten films. The
developed model was validated numerically and experimentally.
Affiliations
Offprint