The integration of superlattices and immersion nonlinear ultrasonics to enhance damage detection threshold
The integration of superlattices and immersion nonlinear ultrasonics to enhance damage detection threshold
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DOI：
10.1063/1.5007771
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发表时间：
2017-11-13
影响因子：
4
通讯作者：
Ozevin, Didem
中科院分区：
文献类型：
--
作者：
Mostavi, Amir;Kabir, Minoo;Ozevin, Didem
我们展示了利用超晶格（SL）增强浸没非线性超声检测（NLUT）。NLUT可以通过测量基波和二次谐波频率来检测固体中的亚波长微观结构变化。二次谐波频率的幅度随着缺陷或其他非均匀性的存在而增加。浸没NLUT是有益的，因为水提供了一致的耦合条件;然而，水产生高非线性，其可以掩盖源自固体中的微结构特征的弱非线性。在本研究中，SL被提出来消除由水和实验仪器引起的非线性。由复合层的周期性布置制成的SL可以提供带隙以限制发射器和接收器之间的特定频率范围的传播。的固体-流体层的周期性排列的数值设计和实验适应浸没NLUT。我们的研究结果意味着，100 μ m厚的玻璃和100 lm厚的水层的周期性阵列提供了一个带隙，阻止4.5 MHz（第二谐波频率），而这种周期性结构通过2.25 MHz（第一谐波频率）。通过检测铝1100试样中与塑性变形相关的微观结构变化，证明了NLUT灵敏度的提高。结果表明，所提出的方法提高了一个数量级的损伤检测灵敏度相比，目前的做法。出版社：AIP Publishing
We demonstrate the enhancement of immersion nonlinear ultrasonic testing (NLUT) by exploiting superlattices (SLs). NLUT can detect sub-wavelength micro-structural changes in solids by measuring the fundamental and second harmonic frequencies. The amplitude of second harmonic frequency increases with the presence of defects or other heterogeneities. The immersion NLUT is beneficial as water provides a consistent coupling condition; however, water generates high non-linearity that can mask the weak non-linearity originated from the micro-structural features in solids. In this research, SLs are proposed to remove the non-linearity arisen from water and experimental instruments. The SLs made of a periodic arrangement of composite layers can provide a band gap to restrict the propagation of a specific range of frequencies between transmitter and receiver. The periodic arrangement of solid-fluid layers is numerically designed and experimentally adapted to the immersion NLUT. Our results imply that the periodic array of 100 mu m thick glass and 100 lm thick water layers provides a band gap that blocks 4.5 MHz (the second harmonic frequency), while this periodic structure passes 2.25 MHz (the first harmonic frequency). The improvement in the sensitivity of the NLUT is demonstrated through detecting the micro-structural changes associated with plastic deformation in aluminum 1100 specimens. It is revealed that the proposed methodology enhances the damage detection sensitivity of immersion NLUT by an order of magnitude as compared to the current practice. Published by AIP Publishing.