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Advances in Materials Science and Engineering
Volume 2014 (2014), Article ID 170279, 12 pages
http://dx.doi.org/10.1155/2014/170279
Research Article

Mechanical Properties Measurement of Polymer Films by Bulge Test and Fringe Projection

1Ph. D. Program of Mechanical and Aeronautical Engineering, Feng Chia University, No. 100 Wen Hwa Road, Taichung 40724, Taiwan
2Department of Applied Mathematics, Feng Chia University, No. 100 Wen Hwa Road, Taichung 40724, Taiwan
3Department of Photonics, Feng Chia University, No. 100 Wen Hwa Road, Taichung 40724, Taiwan
4Department of Electrical Engineering, Feng Chia University, No. 100 Wen Hwa Road, Taichung 40724, Taiwan
5Department of Environmental Engineering and Science, Feng Chia University, No. 100 Wen Hwa Road, Taichung 40724, Taiwan
6Department of Material Science and Engineering, Feng Chia University, No. 100 Wen Hwa Road, Taichung 40724, Taiwan

Received 25 March 2014; Accepted 21 April 2014; Published 20 May 2014

Academic Editor: Chi-Wai Chow

Copyright © 2014 C. S. Lin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper aims at determining the mechanical properties such as Poisson ratio, biaxial modulus, and residual stress of polymer membranes using the bulge test and fringe projection. Under this idea, a bulge test apparatus has been developed for robust usage, under the room temperature, in industrial environments that are usually noisy and full of all kinds of vibrations. A setup of the bulge test, consisting of single chips and digital on-off valves, was used to achieve automatic precision control of pressure application to gas chamber with a circular polyimide (PI) test film fixed on the opening of it. A deformed image was then obtained via fringe projections with a series of optical apparatuses, and a 3D membrane deformation distribution was further achieved from this deformed image by some image processes that are chiefly through wavelet transformation and phase expansion. With the measurements of maximum membrane deformation versus applied pressure and given the Young’s modulus of test membrane, we could further calculate the Poisson ration (and then biaxial modulus) and residual stress of the film. Also, the measurements were validated to be highly accurate by comparison with a finite element analysis.