Estimation of Mechanical Parameters of Thin Films Using Finite Element Analysis

Abstract

This study shows a methodology to estimate mechanical parameters of thin films by means of a bulge test and a numerical approach. The methodology is based on the combination of finite element analysis with a classical analytical method. Finite element modeling was conducted for monolayer (Si3N4) membranes of 2x2mm with the aim to approximate both the load-deflection curves experimentally measured and the classical load-deflection analytical model. Error functions were constructed and minimized to delimit a coupled solution space between Young’s modulus and Poison’s ratio. In a traditional bulge test analysis only one of the elastic properties can be determined due to that there is not unique solution in the estimations of these parameters. However, both elastic parameters were determined through the proposed numerical procedure which compares the deformed surfaces for a specific set of optimal elastic parameters computed. Results show that the estimated elastic properties agree with corresponding values determined by other methods in the literature

Numerical Modeling Approach for the Assessment of Elastic Properties of bi-layer Thin Films Measured by Bulge Test

“…It is seen that both results are well correlated since it agrees with finite element solutions. We can point out that the values determined for the elastic properties correspond to typical values reported in the literature for Si 3 N 4 [7,10,13] and Aluminum [14][15].…”

“…In this process, we can highlight that finite element analysis is a powerful tool to simulate bulge testing technique with the aim to estimate the properties of thin films as demonstrated in different studies [2][3][4][5][6][7]. There are several challenges in the estimations of elastic properties until nowadays, as for example elastic coupling between Poisson's ratio and Young's modulus as it was evidenced by [10]. We propose estimation of the elastic properties in two stages; first stage, applying the procedure proposed by [10] in a monolayer.…”

“…There are several challenges in the estimations of elastic properties until nowadays, as for example elastic coupling between Poisson's ratio and Young's modulus as it was evidenced by [10]. We propose estimation of the elastic properties in two stages; first stage, applying the procedure proposed by [10] in a monolayer. In a second stage, to determine the elastic properties of the studied membrane (knowing properties of the support membrane) by an iterative process with finite element analysis in bi-layer membranes.…”

“…The geometry is defined by the membrane is possible estimate the residual stress of the Aluminium by bending conditions with a proposed numerical strategy. Figure 2 shows the geometrical considerations for the finite element model and the application of the residual stresses, also details of this type of modelling can be reviewed in [10]. In this study, finite element solutions were obtained with ANSYS 16.1 on an ASUS ROG Strix GL553VE (Intel Core (TM) i7-7700HQ CPU @ 2.8 GHz, 16 GB RAM) notebook which was ran in Windows 10 environment in order to verify the proposed numerical procedures.…”

“…This relation is called load-deflection curve and it is analysed by means of different methods that permits to determine the elastic parameters from the experimental data. For example, the fitting of analytical equations and finite element analysis [6][7][8][9][10] are the most used. This paper shows that elastic parameters (Young's modulus and Poisson's ratio) of a bi-layer Si 3 N 4 /Al film can be determined by combining finite element analysis with the classical method to identify properties.…”