Matching Spectroscopy with the Ultrasonic Polar Scan for Advanced NDT of Composites

Abstract

The Pulsed Ultrasonic Polar Scan (P-UPS) is a powerful technique for characterizing anisotropic materials like fiber reinforced plastics. A time-domain analysis of the ultrasonic signals yields amplitude and time-of-flight polar diagrams that provide a fingerprint of the local stiffness properties. Though, this simple analysis ignores a lot of information contained in the ultrasonic signals. In this study, we propose to use the P-UPS technique in combination with the spectroscopic analysis of broadband pulses, to obtain plane wave transmission spectra for all in-plane polar angles. This allows us to combine on one hand the strengths of the P-UPS technique, that does not require a priori knowledge about the sample anisotropy, and on the other hand the frequency-domain analysis that utilizes information contained in the broadband pulses.

Optimal Design Parameters for a Phased-Array-Based Ultrasonic Polar Scan

“…Due to the one-to-one relationship between the C-tensor and the polar plot data by virtue of the Christoffel equations, it is possible to use the data in an plane wave based inversion algorithm to uniquely determine the viscoelastic properties of the material [9], [2], [3], [8]. Alternatively, in order to provide insight into the frequency dependence of the viscoelastic tensor, the measured signals can be analyzed in a spectroscopic manner by transforming the data to the frequency domain [10].…”

Numerical Study of a Phased Array-Based Ultrasonic Polar Scan to Determine Plane-Wave Reflection Coefficients of Plates

“…Similarly, based on experimental data, it was shown for a similar type of plate that a reliable estimation of the Ctensor can be found through this inversion algorithm [8]. As an alternative to using broadband (pulsed) excitation and considering UPS data in the bulk wave regime, the data can also be collected and analyzed in the harmonic regime, thereby focusing on Lamb wave excitation at different frequencies [9], [10]. This spectroscopic approach can provide meaningful insight into the frequency dependent damping behavior of plates.…”