负质量密度声学超材料的反常多普勒效应

发布时间：2018-11-05 15:05

【摘要】：能够按照人们的意愿控制声波的传播一直是研究者们想要解决的问题.一类由人工微结构组成的声学超材料吸引了研究者的注意,因为它具有许多天然材料所不能实现的奇特性质,例如负折射、平板聚焦和反常多普勒等.本文中,我们制备了一种二维的负质量密度声学超材料,在频率1560—5580 Hz范围内质量密度为负值,折射率在1500—5480 Hz范围内为负值,设计了一种测量多普勒效应的测试装置,测试了其在1200—6500 Hz内的多普勒效应.实验结果表明:在所制备的声学超材料负折射区域内,以声源的频率为2000 Hz为例,当声源靠近探测器时,探测器探测到的频率为1999.27 Hz,与声源相比有0.73 Hz的减小;而当声源远离探测器时,探测器探测到的频率为2000.68 Hz,与声源相比有0.68 Hz的增大,即在频率点为2000 Hz时,有明显的反常多普勒现象.对整个负区域内进行选点测量,发现在整个负区域内有宽频带的反常多普勒效应现象.
[Abstract]:The ability to control the propagation of sound waves according to people's wishes has always been a problem that researchers want to solve. A class of acoustical metamaterials made up of artificial microstructures have attracted the attention of researchers because they have many peculiar properties which can not be realized by natural materials such as negative refraction plate focusing anomalous Doppler and so on. In this paper, we have prepared a two-dimensional negative mass density acoustic supermaterial with negative mass density in the frequency range of 1560-5580 Hz and a negative refractive index in the range of 1500-5480 Hz. The Doppler effect in 1200-6500 Hz was measured. The experimental results show that in the negative refraction region of the prepared acoustic supermaterial, the frequency of the sound source is 2000 Hz. When the sound source is close to the detector, the frequency of 1999.27 Hz, detected by the detector decreases by 0.73 Hz compared with the sound source. However, when the sound source is far away from the detector, the frequency detected by the detector is 0.68 Hz higher than that of the sound source at 2000.68 Hz, that is, when the frequency point is 2000 Hz, there is an obvious abnormal Doppler phenomenon. It is found that there is a wide band anomalous Doppler effect phenomenon in the whole negative region by measuring the selected points in the whole negative region.
【作者单位】：西北工业大学理学院智能材料实验室;
【基金】：国家自然科学基金(批准号:11674267,51272215) 国家重点基础研究发展计划(批准号:2012CB921503)资助的课题~~
【分类号】：TB34

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