The Ultrasonic Polar Scan for Composite Characterization and Damage Assessment: Past, Present and Future

Abstract

Abstract:In the early 1980's, the ultrasonic polar scan (UPS) technique was developed to assess the fiber direction of composites in a nondestructive way. In spite of the recognition by several researchers as being a sophisticated and promising methodology for nondestructive testing (NDT) and materials science, little advance was made during the following 30 years. Recently however, the UPS technique experienced a strong revival and various modifications to the original UPS setup have been successfully implemented. This revival has exposed several powerful capabilities and interesting applications of the UPS technique for material characterization and damage assessment. This paper gives a short historical overview of the UPS technique for characterizing and inspecting (damaged) fiber-reinforced plastics. In addition, a few future research lines are given, which will further expand the applicability and potential of the UPS method to a broader range of (damaged) materials, bringing the UPS technique to the next level of maturity.

Numerical study of the Time-of-Flight Pulsed Ultrasonic Polar Scan for the determination of the full elasticity tensor of orthotropic plates

“…The stable nature of the TOF P-UPS inversion procedure for noise addition originates from the simultaneous inversion of the TOF data at several φ-angles, and obviously benefits from the fact that it contains a lot of redundant information. A similar observation regarding the robustness to noise and scatter was already made for the amplitude based P-UPS in [14,15]. Consequently, we can be confident that the P-UPS method has a lot of potential for application in environments where typically lower SNRs are involved.…”

“…The stretched views of the P-UPS images in orthogonal directions are a direct consequence of the unidirectional fiber reinforcement of the investigated [0 • ] 8 C/E composite. Recently, several interesting results have been obtained and reported on the application of the P-UPS method for the valuation of composites, including, amongst others, damage assessment [14,15], (visco)elasticity characterization [14,15] and strain measurement [16]. In the characterization studies, the original P-UPS inversion procedure was based on the amplitude P-UPS in transmission (figure 3b) and incorporated several aspects of the bulk wave approximation [14,15].…”

“…Recently, several interesting results have been obtained and reported on the application of the P-UPS method for the valuation of composites, including, amongst others, damage assessment [14,15], (visco)elasticity characterization [14,15] and strain measurement [16]. In the characterization studies, the original P-UPS inversion procedure was based on the amplitude P-UPS in transmission (figure 3b) and incorporated several aspects of the bulk wave approximation [14,15]. In the first step of the inversion, the characteristic contours in the amplitude P-UPS image, expressing the transmission minima, were matched with computed critical bulk wave angles using a genetic optimization procedure.…”

“…To remediate this deviance, a second step was added to the inversion procedure which accounts for a more thorough description of the relevant physical phenomena (interference and attenuation) by matching the measured and simulated transmission amplitude as function of the incidence angle for a selection of in-plane (φ) angles. The two step procedure finally yielded good inversion results for a range of composites [14,15]. However, because of the insensitivity of the characteristic contours in the P-UPS data to the elastic moduli C i3 , with i = 1, 2, 3, the original amplitude P-UPS inversion procedure [15] only considered part of the orthotropic tensor.…”

Towards a Phased Array Based Ultrasonic Polar Scan: Simulation Study and Comparison with Plane Wave Results

“…The Ultrasonic Polar Scan [3,4] (UPS) is a relatively recent technique which can bypass the former problem. Figure 1a illustrates the basic working principle of the UPS setup.…”