Abstract
Shape optimization of two-dimensional lenses for acoustic cameras used in underwater acoustic imaging is presented. To understand elastic shear wave effects of a lens on the pressure field of the medium, we couple two physics models, namely a pressure acoustics model and a linear elastic model and formulate it in the finite element analysis framework. As a result, the focal length of a lens is calculated to be longer than that in the absence of shear effects. The accuracy of our model is tested against experimental results, and compared with finite element analysis of a single physics model as well as the hybrid method - a method using geometrical acoustics and wave acoustics. Pressure at the focal point is optimized using geometric parameters for lens surfaces as design variables. Performance differences due to temperature change or obliquely incident waves are controlled using design constraints. The effectiveness of our optimization formulation is verified by solving single- and dual-lens design problems.
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Recommended by Associate Editor Jeong Sam Han
Quang Dat Tran received his M.S. degree from Department of Mechanical Engineering, Sejong University, Korea in 2013. He is currently a Ph.D. candidate at Department of Mechanical Engineering, Sejong University. His research interest is topology optimization for acoustic problems.
Gang-Won Jang received a B.S. degree in mechanical engineering from Seoul National University in 1998, M.S. and Ph.D. from Seoul national University in 2000 and 2004, respectively. He is an Associate Professor at Faculty of Mechanical and Aerospace Engineering, Sejong University. His research fields include structural optimization and thin-walled beam analysis based on higher order beam theory.
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Tran, Q.D., Jang, GW., Kwon, HS. et al. Shape optimization of acoustic lenses for underwater imaging. J Mech Sci Technol 30, 4633–4644 (2016). https://doi.org/10.1007/s12206-016-0934-7
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DOI: https://doi.org/10.1007/s12206-016-0934-7