![]() ![]() That sound is sensitive to the anisotropic linear stiffness of composites and has been widely exploited in the past. The 3D beams are modeled by a plane wave expansion based on a Fourier series approach whereby each constituting plane wave interacts with the plate under consideration. Here, we investigate the transmission of acoustic beams perpendicularly incident on an anisotropic plate. However, the effect on beam shape, merely due to anisotropy and not due to impedance inhomogeneity, usually is not considered. It is known that sound transmits through crystals in a directional-dependent manner. Emitting sound through such conventional materials can further adjust beams without sophistication, and, therefore, find applications in the above-mentioned topics of beam-shape, steering and focus adjustments in the medical field. Those substances can be crystals or fiber-reinforced composites, anisotropic but homogeneous for the involved sound waves. In beam-shape modifications, however, the degree of complexity implies that transducer manufacturers might gain from merging metamaterials with traditional substances, if possible. The versatility of metamaterials remains limitless for the time being. Embedded in-plate applications also exist in which metamaterials steer or focus beams. Certain metamaterials achieve anisotropic behavior but not in the homogenized sense of actual crystals or fiber-reinforced composites with constituents way below the involved acoustic wavelengths. Acoustic metamaterials are also developed for making a Mikaelian lens or coding acoustic waves by sending them through the metamaterial before transmission. Acoustic gradient-index (GRIN) metasurfaces, engineered from soft graded-porous silicone rubber, also permit beam steering and focusing. The focus can be adjusted by shifting one material to another, covering the transducer surface. Bessel beams, known for their diffraction resilience, can be formed equally by a metamaterial placed before a transducer. Impedance-based holographic acoustic lenses have been developed to transform the sound output from a transducer into the desired field for medical applications. Metasurfaces are planar metamaterials with a subwavelength thickness that enables wavefront sculpting by introducing gradients in the spatial wave response of these flat structures. ![]() Recently, it has been demonstrated that metasurfaces are efficient and compact structures for designing arbitrary wavefronts. This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. While the results are not exhaustive, they demonstrate the beam shape’s adaptability. ![]() Different incident beam shapes, such as conical-like, Gaussian, and pillar beams, are investigated. The incident sound is presumed to originate from a conventional transducer, possibly coated with a metamaterial to modify the sound field, before being transmitted through the anisotropic layer. This paper investigates the transmission of a circumscribed beam through a stratum of anisotropic material to examine the change in beam shape after transmission. In beam-shape adaptation, however, their complexity suggests that manufacturers of transducers could benefit from combining metamaterials with more conventional materials. For the time being, the versatility of metamaterials remains limitless. In addition to frequency filtering, acoustic lenses offer intriguing possibilities for shaping sound beams. * Corresponding author: are intensely explored for their capabilities to modify sound beams. Woodruff School of Mechanical Engineering, Georgia Tech Europe, Laboratory for Ultrasonic Nondestructive Evaluation, IRL 2958 Georgia Tech – CNRS, 2 rue Marconi, 57070 Metz, France Georgia Institute of Technology, George W. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |