基于激光超声技术的一维声学黑洞结构研究

发布时间：2018-10-16 18:17

【摘要】：近来,在声物理发展前沿,波操控技术为发展新的减振降噪方法提供了可能。声学黑洞结构作为一种典型的波操控结构,近来被广泛关注与研究。理想声学黑洞结构能达到波的零反射,并将所有的波动能量聚集在结构的尖端位置。然而,实际加工出的声学黑洞结构往往带有微小的尖端截断,会破坏结构的零反射特性。在结构尖端粘贴少量阻尼材料,又能减轻这种影响,达到减振降噪的目的。目前对声学黑洞结构的研究多是从频域上分析黑洞效应的效果,缺乏对黑洞效应时域产生过程的研究。此外,关于尖端截断、阻尼层等参数对黑洞效应影响的研究也具有一定的局限性,不利于后期结构的优化设计。本文将激光超声技术引入声学黑洞结构的实验研究中,对一维声学黑洞结构进行了详细的研究分析。首先,实现了弯曲波波场可视化,从时域上展现了弯曲波在一维声学黑洞结构上传播的全过程。本文设计搭建了激光超声实验平台,并提出了虚拟传感器方法来改良传统激光超声技术,模拟线激励信号。其次,分析了弯曲波特性的变化规律,并研究了声学黑洞效应的形成过程。通过小波变换、虚拟传感器等信号处理方法分析实验数据,研究了弯曲波波速、振幅等特性的变化规律,并探讨了声学黑洞结构的能量聚集效应。最后,确立了基于反射系数的一维声学黑洞效应评价标准,研究了参数变化对一维声学黑洞效应的影响。提出了一种基于波场分离原理计算结构反射系数的新方法,讨论了尖端截断和阻尼层等参数对声学黑洞效应的影响,优化了声学黑洞结构的参数选择。
[Abstract]:Recently, in the forefront of the development of acoustic physics, wave manipulation technology provides the possibility for the development of new vibration and noise reduction methods. As a typical wave control structure, acoustical black hole structure has been widely studied recently. The ideal acoustic black hole structure can achieve zero reflection of the wave and gather all the wave energy at the tip of the structure. However, the fabricated acoustical black hole structures often have tiny truncation of the tip, which will destroy the zero reflection characteristics of the structure. A small amount of damping material is attached to the tip of the structure, which can reduce this effect and achieve the purpose of reducing vibration and noise. At present, the study of acoustical black hole structure is mostly to analyze the effect of black hole effect from frequency domain, but lack of research on black hole effect generation process in time domain. In addition, the study of the influence of the parameters such as tip truncation and damping layer on the black hole effect also has some limitations, which is not conducive to the optimization design of the late structure. In this paper, the laser ultrasonic technique is introduced into the experimental study of acoustic black hole structure, and the one-dimensional acoustic black hole structure is analyzed in detail. Firstly, the visualization of the curved wave field is realized, and the whole process of the curved wave propagating on the one-dimensional acoustic black hole structure is shown from the time domain. In this paper, a laser ultrasonic experimental platform is designed and built, and a virtual sensor method is proposed to improve the traditional laser ultrasonic technology to simulate the linear excitation signal. Secondly, the variation of bending wave characteristics is analyzed, and the formation process of acoustical black hole effect is studied. By means of wavelet transform, virtual sensor and other signal processing methods, the experimental data are analyzed, and the variation rules of wave velocity and amplitude are studied, and the energy aggregation effect of acoustic black hole structure is discussed. Finally, the evaluation standard of one-dimensional acoustical black hole effect based on reflection coefficient is established, and the influence of parameter variation on one-dimensional acoustic black hole effect is studied. A new method for calculating the reflection coefficient of a structure based on the principle of wave field separation is proposed. The influence of the parameters such as truncation of the tip and damping layer on the acoustic black hole effect is discussed and the selection of the structural parameters of the acoustic black hole is optimized.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O42;TN249

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