2-D and 3-D Lamb-Wave Spectrum Analysis Using Complex Transducer Points
In prior studies of Gaussian beam reflection from immersed plates [1–5], it is shown that the reflected field or receiver voltage as a function of transducer position, at any incident angle, can be calculated or measured at constant frequency, and the 2-D calculated reflected field or receiver voltage in the incident plane is almost the same as a 3-D calculation, except for a scale factor as we show later in this paper. This is not the case, however, for the reflection and transmission frequency spectrum, which is widely used to infer the plate material parameters [6,7]. In this paper we extend the complex transducer point (CTP) to this widely used ultrasonic Lamb wave technology. We show that the reflection frequency spectrum requires a full 3-D voltage calculation to achieve the desired accuracy under all conditions. The 3-D receiver voltage frequency spectrum calculated here is compared to extensive experimental results on several materials and in different experimental configurations. The results show that the 3-D voltage spectrum calculation must be used under some conditions to make accurate deductions of material parameters.
KeywordsIncident Angle Reflection Coefficient Shear Velocity Fiber Direction Specular Reflection
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- 8.Unidirectional: C 11 =143.0, C 12 =3.7, C 22 =16.5, C 12 =7.6, C 55 =8–3, d = 0.92mm, p = 1.60g/cm 3 Biaxial: C 11 =133.0, C 12 =3.7, C 22 =15.5, C 12 =7.6, C 55 =6.3, d = 1.52mm, p = 1.62g /cm 3 Google Scholar
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