Propagation of Acoustic Waves in Periodic and Random Two-dimensional Composite Media
- PDF / 217,070 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 1 Downloads / 186 Views
MATERIALS RESEARCH
Welcome
Comments
Help
Propagation of acoustic waves in periodic and random two-dimensional composite media J. O. Vasseur Equipe de Dynamique des Interfaces, Laboratoire de Dynamique et Structure des Mat´eriaux Mol´eculaires, U.R.A. C.N.R.S. n± 801, U.F.R. de Physique, Universit´e de Lille I, 59655 Villeneuve d’Ascq C´edex, France
P. A. Deymier Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721 (Received 1 August 1994; accepted 27 January 1997)*
Transmission of acoustic waves in two-dimensional composite media composed of arrays of Duralumin cylindrical inclusions embedded in a poly vinyl chloride (PVC) matrix is studied. Experimental and theoretical results for the transmission spectrum of a periodic array of cylinders organized on a square lattice are reported. Local gaps in the first two-dimensional Brillouin zone are predicted and observed. The experimental measurements of power spectra for a random array of inclusions show a weak correlation between disorder and acoustic absorptions up to a high degree of disorder. Only in the case of highly random arrangements does the transmission spectrum diverge from the one obtained with a periodic array of inclusions. I. INTRODUCTION
The problem of propagation of classical waves in composite media has recently received a great deal of attention. Of particular interest is the existence of gaps in the optical or acoustic band structure of periodic and random composite media. The band structure of dielectric composites is the object of extensive theoretical and experimental studies.1 The subject of propagation of acoustic waves in inhomogeneous media has also been investigated theoretically.2–5 These investigations focus on two-dimensional composite media composed of periodic arrays of fibers in a matrix. Under the condition of large difference in elastic properties of the matrix and fibers, these materials exhibit gaps in the acoustic band structure. In this paper, we report a combined experimental and theoretical study of acoustic waves propagation in twodimensional periodic and random bimaterial composites. In Sec. II we present the experimental method and the tested composite samples. The theoretical calculation of the acoustic band structure of the periodic system is reported in Sec. III. The experimental and theoretical results for the periodic and the random specimens are discussed in Sec. IV. Finally, some conclusions regarding the propagation of acoustic waves in inhomogeneous media are drawn in Sec. V. II. EXPERIMENTAL METHOD A. Composite systems
The periodic composite medium is constituted of an array of 25 parallel cylinders of Duralumin (Al 95%–Cu *
The Editor would like to point out that this paper was delayed due to the editorial process and not due to the authors or paper quality. J. Mater. Res., Vol. 12, No. 8, Aug 1997
http://journals.cambridge.org
Downloaded: 18 Mar 2015
4%–Mg 1% alloy) arranged on a 5 3 5 square lattice in a poly vinyl chloride (PVC) cubic matrix. The metallic cylin
Data Loading...
