| Summary: | 碩士 === 國立臺灣大學 === 工程科學及海洋工程學研究所 === 103 === This article presents methods for modeling, analysis, and design of practical metamaterial with simultaneously negative mass density and Young’s modulus. Metamaterials are man-made materials that make objects exhibit behavior defferent from the general laws of physics by changing the geometry and dimensions. Metamaterial research extends from the electromagnetic into acoustic and solid mechanics. By defferent mechanism such as translational or rotational vibration, elastic solid metamaterials would be the equivalent models of media having negative mass density, negative Young’s modulus, or negative bulk modulus in excitation force.
The thesis id divided into three parts. First, through theoretical metamaterial model having double negativities, spring-mass system and trusses construct a practical model. We separate the practical model into four different sizes and expect to find the negative slope line in the dispersion curve. The effect of the practical model is explicitly confirmed by analysis of wave propagation using numerical simulation in ABAQUS. By numerical simulation, we find the practical mode having anomalous wave propagation called backward wave. Sencod, we create two-dimensional acoustic metamaterial having simultaneously negative mass density and Young’s modulus. The dipersion curve of two-dimensional model also has the negative slope line which represents special wave propagation phenomenon. Finally, we try to apply the practical model to the present engineering field.
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