Electronic Journal Technical Acoustics ISSN 1819-2408

E. Mfoumou, C. Hedberg, S. Kao-Walter

Static versus low frequency dynamic elastic modulus measurement of thin films

language: English

received 10.10.2006, published 22.12.2006

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ABSTRACT

A new experimental technique for evaluating Young’s (or elastic) modulus of a vibrating thin film from a dynamic measurement is presented. The technique utilizes bending resonance from a remote acoustic excitation to determine Young’s modulus. Equations relating the natural frequencies to the mechanical properties are obtained, and Young’s modulus is subsequently determined. Young’s modulus values from dynamic test are compared with those (static) obtained by a standard tensile test, and consistent results are obtained. The proposed technique is relatively simple and could be used to determine Young’s modulus of a wide variety of sheet materials initially having no bending stiffness. It can also be used for determining other mechanical properties, such as compliance methods in connections with fracture mechanical testing, fatigue and damage measurements. This work emphasizes the feasibility of a damage assessment of components in-service by evaluating changes in the material characteristics.

16 pages, 9 figures

Сitation: E. Mfoumou, C. Hedberg, S. Kao-Walter. Static versus low frequency dynamic elastic modulus measurement of thin films. Electronic Journal “Technical Acoustics”, http://www.ejta.org, 2006, 17.

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		Etienne Mfoumou is a PhD student at Blekinge Institute of Technology in Sweden, working on Acoustic Methods in Defect Analysis of Thin Layered Materials. He got his MSc degree in 2003 and his Licentiate degree on “Remote Acoustic Characterization of Thin Sheets” in 2006, both from the same institution. e-mail: etienne.mfoumou(at)bth.se
		Claes Hedberg got his PhD on "Theoretical Studies of Nonlinear Propagation of Modulated Harmonic Sound Waves" from Royal Institute of Technology, Stockholm in 1995. He spent two years as a post-doc at University of Texas - Austin before joining Blekinge Institute of Technology in Sweden in 1997. He is co-author of two books: "Theory of Nonlinear Acoustics in Fluids" by B.O. Enflo and C.M. Hedberg, 2002, and “Nonlinear acoustics through problems and examples”, by O. Rudenko, S. Gurbatov, and C. Hedberg (Russian Edition: 2006; English edition: to appear 2006). His main interests are currently within Nonlinear Acoustic, Non-Destructive Testing and Parametric loudspeakers.
		Sharon Kao-Walter received her Bachelor of Science in Eng. in 1982 from Shanghai Jiao-Tong University in China. In 1991 she got her Licentiate of Tech. degree at Lund Institute of Technology, Sweden with the thesis: “Crack Growth Initiation of a Quarter Notched 3PB Ductile Specimen under High Velocity Impact”. After several years worked as material development engineer in a packaging company, she received the PhD degree in 2005 from Blekinge Institute of Technology in Sweden with the thesis: ”On the Fracture of Thin Laminates”. She is currently associated professor at Blekinge Institute of Technology in Sweden and guest professor at Kunming University of Science and Technology in China. Scientific interests: fracture mechanics of composites and nano-materials in packaging and in other applications.