Damage localization method for plates based on the time reversal of the mode-converted Lamb waves
Damage localization method for plates based on the time reversal of the mode-converted Lamb waves
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DOI：
10.1016/j.ultras.2018.07.007
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发表时间：
2019-01-01
期刊：
影响因子：
4.2
通讯作者：
Kusaka, Takayuki
中科院分区：
文献类型：
--
作者：
Mori, Naoki;Biwa, Shiro;Kusaka, Takayuki
提出了一种基于模式转换散射Lamb波时间反转聚焦的板结构损伤定位方法。双换能器对称地附接在板的上表面和下表面上，以选择性地发射和接收最低阶对称（S0）和反对称（A0）模式。损伤的定位是通过数值时间反演（TR）模拟的模式转换的兰姆波产生的缺陷。为了验证该方法的有效性，采用三维弹性动力学有限积分法（EFIT）对含部分厚度切口板中的Lamb波信号进行了数值模拟。当在受损板中发射S0模时，不仅S0模被散射，而且由于在凹口处的模转换而产生A0模。当发射A0模式时，确认了类似的模式转换行为。模式转换的散射兰姆波的时间反转在损伤位置处产生聚焦点，而不使用未损伤板的基线数据。所提出的方法相比，非模式转换的兰姆波的时间反转的伪影的幅度减小，并且产生聚焦光斑，其大小与凹口的大小和时间反转的波模式的半波长相关联。此外，所提出的方法被应用到一个板与缺口型缺陷相邻的先验已知的通厚度孔，演示了在一个相对复杂的结构的损伤定位。
A damage localization method based on the time reversal focusing of the mode-converted scattered Lamb wave is proposed for plate structures with a non-symmetric defect in the thickness direction. Dual transducers are attached symmetrically on the upper and lower surfaces of the plate to selectively emit and receive the lowest-order symmetric (S0) and antisymmetric (A0) modes. The localization of damage is achieved by the numerical time-reversed (TR) simulation of the mode-converted Lamb wave generated at the defect. To investigate the validity of the proposed method, the signals of the Lamb waves in a plate with a partial-thickness notch are numerically simulated by the three-dimensional elastodynamic finite integration technique (EFIT). When the S0 mode is emitted in the damaged plate, not only the S0 mode is scattered but also the A0 mode is generated due to mode conversion at the notch. Similar mode conversion behavior is confirmed when the A0 mode is emitted. The time reversal of the mode-converted scattered Lamb waves creates focused spots at the damage location without using baseline data for the undamaged plate. The proposed method reduces the magnitude of the artifacts compared to the time reversal of the non-mode-converted Lamb wave, and yields the focused spot whose size is associated with the size of the notch and the half wavelength of the time-reversed wave mode. Furthermore, the proposed method is applied to a plate with a notch-type defect adjacent to an a priori known through-thickness hole, demonstrating the damage localization in a relatively complicated structure.