Iranian Society of Acoustics and Vibration and Avecina Journal of Theoretical and Applied Vibration and Acoustics 2423-4761 12 1 2026 01 01 Design and simulation of acoustic metamaterial luneburg lenses for predetermined focal points 1 15 728761 10.22064/tava.2025.2061787.1265 EN Mohammad Naeim Moradi PhD student, Acoustics Research Laboratory, Mechanical Engineering Department, Amirkabir University of Technology (Tehran Polytechnic), Tehran, IRAN. 0000-0003-3133-994X Maryam Ghasabzadeh Assistant Professor, Vehicle Technology Research Institute, Amirkabir University of Technology (Tehran Polytechnic), Tehran, IRAN. Abdolreza Ohadi Professor, Acoustics Research Laboratory, Mechanical Engineering Department, Amirkabir University of Technology (Tehran Polytechnic), Tehran, IRAN. 0000-0001-6514-4089 Journal Article 2025 05 26 <span>This paper presents the design and simulation of acoustic metamaterial lenses that focus elastic waves at predetermined focal points. <span>The modified Luneburg refractive index profile is used in the design process to define focal point locations, a capability not previously explored in elastic wave research.</span><span> This new approach is important because it enables more precise spatial control of waves, resulting in enhanced resolution for elastic wave focusing applications.</span><span> </span>Three lenses, each targeting specific focal points, are designed by proposing hexagonal unit cells containing blind holes with varying diameters. Dispersion curves are calculated by finite element simulations to determine wave properties of unit cells, including refractive indices. These unit cells provide a wide range of refractive indices (1.0314-1.4959) at the design frequency of 50 kHz, which is suitable for constructing Luneburg lenses. Unit cells are then arranged according to the discretized refractive index profiles to form the lenses. Numerical simulations validate effective wave focusing at the intended focal points (F=R, 1.5R, 2R) with three lenses. The highest amplification of waves and the narrowest focal zone are for the lens with F=R. As the focal point shifts toward 2R, wave distribution becomes scattered along the focal axis. Decay length analysis of F=1.5R and 2R lenses indicates their suitability for long distribution of high-velocity regions. Frequency-dependent simulations across 46–52 kHz reveal that all lenses maintain efficient focusing between 49–51 kHz. At more distant off-design frequencies, amplifications result from refractive index shifts that misalign the focal point.</span> https://tava.isav.ir/article_728761_254cc17c295b0b240b7ab68c79fd5829.pdf