International Journal of Physics | Vol. 17, No. 8, August 2026 | pp. 121–128
DOI: 10.46882/2026/IJP/000204
Research Article
Title: Acoustic Wave Scattering and Waveguide Defect Modes in Elastic Phononic Crystals
Names of Authors: A. M. El-Sayed¹, G. B. Zhou², H. J. Mueller³
Authors’ Affiliations:
¹ Department of Physics, Faculty of Science, Ain Shams University, Cairo, Egypt
² Department of Materials Science, Fudan University, Shanghai, China
³ Institute of Physics, Karlsruher Institut für Technologie, Karlsruhe, Germany
Abstract: Phononic crystals offer exceptional capabilities for manipulating acoustic waves through the formation of complete elastic band gaps. This study examines the propagation of acoustic waves in a two-dimensional phononic crystal consisting of copper cylinders arranged in a square lattice embedded within an epoxy matrix. We performed finite element method (FEM) simulations using the plane wave expansion technique to compute the acoustic band structures. The cylinder radius-to-lattice pitch ratio (r/a) was varied from 0.20 to 0.45 to systematically optimize the system parameters. Our calculations revealed a wide, complete acoustic band gap for both transverse and longitudinal modes within the normalized frequency range of 0.35 to 0.58 when r/a was optimized at 0.42. To validate these numerical simulations, we fabricated a physical prototype containing 10.0 x 10.0 rods positioned within an acrylic frame and filled with liquid epoxy resin. Ultrasonic transmission measurements were performed using water-immersed piezoelectric transducers across a frequency range from 20.0 kHz to 200.0 kHz. The experimental transmission spectra demonstrated a profound acoustic attenuation of up to -45.0 dB within the predicted band gap region, demonstrating excellent agreement with the FEM models. Introducing a line defect into the lattice configuration successfully created an acoustic waveguide channel. This channel demonstrated a high transmission efficiency of 88.0% for localized defect modes, demonstrating the utility of this design for acoustic filtering and noise-isolation.
Keywords: Phononic crystals; Acoustic band gap; Finite element method; Ultrasonic transmission; Waveguide; Elastic waves
Manuscript Timeline: Received: June 12, 2026 / Revised: July 15, 2026 / Accepted: August 03, 2026 / Published: August 21, 2026
Citation: El-Sayed, A. M., Zhou, G. B., & Mueller, H. J. (2026). Acoustic Wave Scattering and Waveguide Defect Modes in Elastic Phononic Crystals. International Journal of Physics, 17(8), 121–128.
Subscribe to read the full article: https://internationalscholarsjournals.org/subscribe-to-read