Galán José M, Abascal Ramón
Escuela Superior de Ingenieros, Universidad de Sevilla, Camino de los Descubrimientos s/n, E-41092 Sevilla, Spain.
Ultrasonics. 2004 Apr;42(1-9):877-82. doi: 10.1016/j.ultras.2004.01.072.
The remote inspection for defects in large metallic elements such as pipes, tubes and plates is a field where guided waves are being applied with success. There are a number of situations where a surface coating is added for corrosion protection or insulation purposes. Since the coating materials are usually viscoelastic, the guided wave inspection range may be severely reduced unless a proper mode and an adequate frequency range is selected. Previous authors found the existence of low-attenuated modes at certain frequency ranges, which were used to detect and locate defects at reasonably large distances. This paper studies the potential of guided waves for not only locating but also sizing defects in plates with viscoelastic coatings. A hybrid finite element-boundary element method which explicitly includes the attenuating characteristics of the coating is used to determine Lamb and SH mode conversion factors at corrosion defects under the coating. Through parametric studies and analysis of the numerical results, some trends and features are highlighted that could be used for sizing purposes.
对管道、管材和板材等大型金属元件中的缺陷进行远程检测是一个成功应用导波的领域。在许多情况下，为了防腐或绝缘目的会添加表面涂层。由于涂层材料通常是粘弹性的，除非选择合适的模式和足够的频率范围，否则导波检测范围可能会严重减小。先前的作者发现，在某些频率范围内存在低衰减模式，这些模式被用于在相当大的距离处检测和定位缺陷。本文研究了导波不仅用于定位有粘弹性涂层板材中的缺陷，还用于确定缺陷尺寸的潜力。一种明确包含涂层衰减特性的混合有限元-边界元方法被用于确定涂层下腐蚀缺陷处的兰姆波和SH模式转换因子。通过参数研究和数值结果分析，突出了一些可用于尺寸确定目的趋势和特征。
