info:eu-repo/semantics/article
Vibration modeling and testing of bilayer beams for determination of film elastic modulus
Autor
FRANCIS AVILES CETINA
Resumen
Analysis of the main parameters affecting the fundamental vibrating frequency of
film/substrate bilayer beams of rectangular cross-section is discussed based on modeling and
testing. Initially, the limits of validity of two analytical models to obtain the fundamental
frequency of perfectly-bonded bilayer beams in cantilever configuration are determined by
comparing the predicted frequencies to a finite element model developed herein. Using a
selected analytical formulation, a modeling-assisted methodology is employed to investigate
the parameters that are most influential on the determination of the elastic modulus of the film
using a vibratory technique. Modeling suggests the use of thin compliant substrates for
extracting the modulus of stiff (metallic) films. If the substrate is stiffer than the film, a thicker
film is required to yield measurable shifts in the resonant frequency. The elastic modulus of a
millimeter-thick thermosetting polymer extracted by this method agrees with the results
obtained from conventional tensile testing of the polymer. Measurements carried out on a gold
(100 nm)/polysulfone (130μm) system yield an average elastic modulus of the gold film
similar to the values reported in the literature.