Analytical and numerical studies of approximate phase velocity matching based nonlinear S0 mode Lamb waves for the detection of evenly distributed microstructural changes
Analytical and numerical studies of approximate phase velocity matching based nonlinear S0 mode Lamb waves for the detection of evenly distributed microstructural changes
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基于非线性 S0 模式兰姆波的近似相速度匹配的分析和数值研究，用于检测均匀分布的微观结构变化
DOI：
10.1088/0964-1726/25/4/045023
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发表时间：
2016-03
影响因子：
4.1
通讯作者：
Zhang Q
中科院分区：
文献类型：
--
作者：
Wan X;Tse P W;Xu G H;Tao T F;Zhang Q
以往对非线性Lamb波的研究大多是在满足严格相速度匹配和非零功率通量准则的模式对上进行的。然而，存在一些局限性。首先，在整个频带内不存在严格的相速匹配;其次，激励中心频率并不总是完全等于真实相速匹配频率;第三，模式对是孤立的，并且在数量上相当有限;第四，激励单个期望的主模式在实践中是极其困难的，并且接收到的信号相当难以处理和解释。很少有人注意解决这些缺点。为了克服这些局限性，本文提出了满足近似相速度匹配的低频非线性S 0模兰姆波。在分析研究中，二次振幅与传播距离考虑基频，最大累积传播距离（MCPD）与基频和最大线性累积传播距离（MLCPD）使用线性回归分析进行了研究。基于分析结果，近似相速度匹配被定量地表征为相对相速度偏差小于1%的阈值。数值研究也进行了使用纯音作为激励信号。研究了中心频率和频带宽度对次级振幅和MCPD的影响。分别采用基频为1.8MHz的S1-S2模、中心频率为100和200 kHz的主S 0模计算了Al 6061-T6与Al 7075-T651的非线性参数之比。计算值与实际值的接近一致性验证了满足近似相速度匹配的非线性S 0模式Lamb波表征材料非线性的有效性。此外，由非线性S 0模式Lamb波产生的一次和二次水平位移的比值最接近于真实的值，这表明利用水平位移更适合于检测大型薄板状结构中均匀分布的微结构变化。成功地应用于评估材料在不同水平的均匀分布的疲劳损伤的数值进行。
Most previous studies on nonlinear Lamb waves are conducted using mode pairs that satisfying strict phase velocity matching and non-zero power flux criteria. However, there are some limitations in existence. First, strict phase velocity matching is not existed in the whole frequency bandwidth; Second, excited center frequency is not always exactly equal to the true phase-velocity-matching frequency; Third, mode pairs are isolated and quite limited in number; Fourth, exciting a single desired primary mode is extremely difficult in practice and the received signal is quite difficult to process and interpret. And few attention has been paid to solving these shortcomings. In this paper, nonlinear S0 mode Lamb waves at low-frequency range satisfying approximate phase velocity matching is proposed for the purpose of overcoming these limitations. In analytical studies, the secondary amplitudes with the propagation distance considering the fundamental frequency, the maximum cumulative propagation distance (MCPD) with the fundamental frequency and the maximum linear cumulative propagation distance (MLCPD) using linear regression analysis are investigated. Based on analytical results, approximate phase velocity matching is quantitatively characterized as the relative phase velocity deviation less than a threshold value of 1%. Numerical studies are also conducted using tone burst as the excitation signal. The influences of center frequency and frequency bandwidth on the secondary amplitudes and MCPD are investigated. S1–S2 mode with the fundamental frequency at 1.8 MHz, the primary S0 mode at the center frequencies of 100 and 200 kHz are used respectively to calculate the ratios of nonlinear parameter of Al 6061-T6 to Al 7075-T651. The close agreement of the computed ratios to the actual value verifies the effectiveness of nonlinear S0 mode Lamb waves satisfying approximate phase velocity matching for characterizing the material nonlinearity. Moreover, the ratios derived from the primary and secondary horizontal displacements generated from nonlinear S0 mode Lamb waves are closest to the real value, which indicates that using horizontal displacements is more suitable for detecting evenly distributed microstructural changes in large thin plate-like structure. Successful application to evaluating material at different levels of evenly distributed fatigue damage is also numerically conducted.
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影响因子：
3.2
作者：
Yang Liu;C. Lissenden;J. Rose
通讯作者：
Yang Liu;C. Lissenden;J. Rose
影响因子：
4.1
作者：
Lu, Ye;Ye, Lin;Su, Zhongqing
通讯作者：
Su, Zhongqing
影响因子：
2.7
作者：
Hurley, DC;Balzar, D;Purtscher, PT
通讯作者：
Purtscher, PT
影响因子：
6
作者：
S. P. Sagar;Das Saumya;N. Parida;D. Bhattacharya
通讯作者：
S. P. Sagar;Das Saumya;N. Parida;D. Bhattacharya
影响因子：
4
作者：
Bermes, Christian;Kim, Jin-Yeon;Jacobs, Laurence J.
通讯作者：
Jacobs, Laurence J.