Partial Analysis Method Combined with Mode-exciting Method in the Analysis of Lamb Waves Scattering by a Crack in a Plate
Partial Analysis Method Combined with Mode-exciting Method in the Analysis of Lamb Waves Scattering by a Crack in a Plate
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DOI：
10.2208/journalam.8.151
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发表时间：
2005-08
期刊：
影响因子：
--
通讯作者：
A. Gunawan;S. Hirose
中科院分区：
文献类型：
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作者：
A. Gunawan;S. Hirose
兰姆波超声无损检测薄板缺陷的方法近年来受到了广泛的关注。Lamb波的频散关系、波动等性质在许多著作中已作了详细的研究和总结1）、2）、3）。然而，知识的兰姆波散射特性的各种类型的缺陷仍然是不够的定量评估的一个板。这是由于兰姆波散射机制的复杂性，其特征在于模式转换包括有限数量的传播模式和无限数量的非传播模式。兰姆波散射分析的研究已经用多种方法进行了。Rokhlin（4），5），6）应用Wiener-Hopf技术的解析方法求解了半无限长和有限长裂纹对Lamb波的散射问题。Liu和Achenbach 7）应用条元法研究了各向异性层合板中裂纹对波的散射。作为频域中兰姆波散射分析的数值方法，Koshiba等人8）和Al-Nassar等人9）应用了有限元法（FEM），而Cho和Rosem等人11）应用了边界元法（BEM）。Galan 12）还发展了一种有限元和边界元的混合方法。由于兰姆波的散射问题通常是针对无限长板的，因此，频域有限元法或边界元法不能单独用于求解散射问题。它们必须与其他技术相结合，如简正模展开技术，以表达无穷远的波场。近年来，作者提出了用模式激励法求解各种兰姆波散射问题。模式激励方法使我们能够在有限区域内进行数值分析，以解决无限区域的散射问题。由于这一优点，在模态激励方法中，有限元法和边界元法等数值方法可以单独使用，而不需要与其他方法耦合。
Lamb wave ultrasonic method in detecting a defect nondestructively in a thin plate has recently attracted great attention. The properties of Lamb waves such as dispersion relation and wave motion have been studied in detail and summarized in many books1),2),3). However, knowledge about scattering properties of Lamb waves by various types of defects is still insufficient for quantitative evaluation of a plate. This is due to complexity of the scattering mechanism of Lamb waves which is characterized by the mode conversion including a finite number of propagating modes and also an infinite number of nonpropagating modes. The studies on the scattering analysis of Lamb waves have been carried out by various methods. Rokhlin4),5),6) has applied an analytical method of the Wiener-Hopf technique to solve the scattering problem of Lamb waves due to cracks with semi-infinite length and finite length. Liu and Achenbach7) applied the strip element method to investigate wave scattering by cracks in anisotropic laminated plates. As numerical methods for the scattering analysis of Lamb waves in the frequency domain, Koshiba et al8) and Al-Nassar et al.9) have applied a finite element method (FEM), whereas Cho and Rosem),11) have applied a boundary element method (BEM). Galan12) has also developed a hybrid method of finite element and boundary element formulation. Since the scattering problem of Lamb waves is usually formulated for a plate of infinite length, however, FEM or BEM in the frequency domain can not be individually used in solving the scattering problem. They have to be coupled with other technique such as the normal mode expansion technique to express the wave field in the infinity. Recently, the authors13) have proposed the mode-exciting method to solve various types of Lamb wave-scattering problems. The mode-exciting method enables us to perform the numerical analysis in a finite domain to solve the scattering problem for the infinite domain. Owing to this benefit, in the modeexciting method, the numerical method such as FEM and BEM can be used individually without coupling with other technique.