Title Participants Abstract "Efficient extraction of the directional wave curves from a pulsed ultrasonic polar scan experiment" "Mathias Kersemans, Nicolas Lammens, Wim Van Paepegem, Koen Van Den Abeele, Lincy Pyl, Filip Zastavnik, Hugo Sol, Joris Degrieck" "The pulsed ultrasonic polar scan (UPS) technique provides an amplitude map with characteristic contours reflecting the critical bulk wave angles, which relate to the mechanical stiffness of the insonified material spot. Besides these contours, additional information is captured in a UPS experiment which has particular importance for the inspection of anisotropic materials. By extensive post-processing on a single UPS experiment, we successfully extracted (i) the critical bulk wave angles, (ii) the phase velocity profile, (iii) the slowness vector, (iv) the walk-off angles and (v) the energy velocity profile, and this for the three different polarization states of bulk waves. The procedure is demonstrated and discussed for an aluminum sample as well as an autoclave manufactured orthotropic [0]8 carbon/epoxy laminate, both having arbitrary dimensions. Comparison with numerical computations yield good agreement. It is worth noting that the carbon/epoxy laminate shows an extraordinary large walk-off angle of more than 70° for the longitudinally polarized wave." "Extraction of bulk wave characteristics from a pulsed ultrasonic polar scan" "Mathias Kersemans, Nicolas Lammens, Joris Degrieck, Koen Van Den Abeele, Lincy Pyl, Filip Zastavnik, Hugo Sol, Wim Van Paepegem" "The pulsed ultrasonic polar scan (P-UPS) technique provides a map with characteristic contours reflecting the critical bulk wave angles, which directly relate to the in-plane elastic properties of the insonified material spot. Besides these contours, additional information is captured in a P-UPS experiment which has particular importance for the inspection of anisotropic materials. By extensive post-processing on a single P-UPS experiment, we successfully extracted the local directional (i) critical bulk wave angles, (ii) phase velocity profiles, (iii) slowness curves, (iv) walk-off angles and (v) energy velocity profiles, for the three different polarization states of bulk waves. The procedure is demonstrated and discussed for an isotropic aluminum sample as well as an autoclave manufactured orthotropic [o](8) carbon/epoxy laminate. In addition, a numerical and experimental investigation of the role of the immersion liquid as a lens for the P-UPS result is performed. This lensing effect permits to zoom in/out on the P-UPS fingerprint, hence broadening the class of materials which can be inspected by the P-UPS technique. (C) 2014 Elsevier B.V. All rights reserved." "Damage Signature of Fatigued Fabric Reinforced Plastics in the Pulsed Ultrasonic Polar Scan" "Mathias Kersemans, Ives De Baere, Koen Van Den Abeele, Joris Degrieck, Lincy Pyl, Filip Zastavnik, Hugo Sol, Wim Van Paepegem" "This study investigates the use of both the amplitude and time-of-flight based pulsed ultrasonic polar scan (P-UPS) for the nondestructive detection and evaluation of fatigue damage in fabric reinforced composites. Several thermoplastic carbon fabric reinforced PPS specimens (CETEX), loaded under various fatigue conditions, have been scanned at multiple material spots according to the P-UPS technique in order to extract material degradation in a quantitative way. The P-UPS results indicate that shear dominated fatigued carbon/PPS goes with a reduction of shear properties combined with large fiber distortions. The P-UPS results of the tension-tension fatigued carbon/PPS samples on the other hand reveal a directional degradation of the stiffness properties, reaching a maximum reduction of -12.8 % along the loading direction. The P-UPS extracted damage characteristics are fully supported by simulations, conventional destructive tests as well as visual inspection. The results demonstrate the excellent capability of the P-UPS method for nondestructively assessing and quantifying both shear-dominated and tension-tension fatigue damage in fabric reinforced plastics." "Nondestructive damage assessment in fiber reinforced composites with the pulsed ultrasonic polar scan" "Mathias Kersemans, Ives De Baere, Joris Degrieck, Koen Van Den Abeele, Lincy Pyl, Filip Zastavnik, Hugo Sol, Wim Van Paepegem" "This study investigates the use of both amplitude and time-of-flight based pulsed ultrasonic polar scan (P-UPS) as a sophisticated non-destructive damage sensor for fiber reinforced composites. Focus is put on stiffness related damage phenomena, which are in general difficult to monitor nondestructively, and their associated signature in the P-UPS image. Various composite samples, with different damage states, have been inspected at multiple material spots with the P-UPS technique. The results demonstrate the capability of the P-UPS method to obtain a unique signature of the local material damage characteristics. Several indicators in the acquired P-UPS images have been identified from which the type and level of material degradation can be obtained. The P-UPS extracted characteristics are fully supported by simulations, conventional tests as well as visual inspection." "Efficient extraction of the directional wave curves from a pulsed ultrasonic polar scan experiment" "Mathias Kersemans, Nicolas Lammens, Koen Van Den Abeele, Lincy Pyl, Filip Zastavnik, Hugo Sol, Joris Degrieck" "The pulsed ultrasonic polar scan (UPS) technique provides an amplitude map with characteristic contours reflecting the critical bulk wave angles, which relate to the mechanical stiffness of the insonified material spot. Besides these contours, additional information is captured in a UPS experiment which has particular importance for the inspection of anisotropic materials. By extensive post-processing on a single UPS experiment, we successfully extracted (i) the critical bulk wave angles, (ii) the phase velocity profile, (iii) the slowness vector, (iv) the walk-off angles and (v) the energy velocity profile, and this for the three different polarization states of bulk waves. The procedure is demonstrated and discussed for an aluminum sample as well as an autoclave manufactured orthotropic [0]8 carbon/epoxy laminate, both having arbitrary dimensions. Comparison with numerical computations yield good agreement. It is worth noting that the carbon/epoxy laminate shows an extraordinary large walk-off angle of more than 70° for the longitudinally polarized wave." "Identification of the elastic properties of isotropic and orthotropic thin-plate materials with the pulsed ultrasonic polar scan" "Mathias Kersemans, Arvid Martens, Nicolas Lammens, Koen Van Den Abeele, Joris Degrieck, Filip Zastavnik, Lincy Pyl, Hugo Sol, Wim Van Paepegem" "Already in the early 1980's, it has been conjectured that the pulsed ultrasonic polar scan (P-UPS) provides a unique fingerprint of the underlying mechanical elasticity tensor at the insonified material spot. Until now, that premise has not been thoroughly investigated, nor validated, despite the opportunities this would create for NDT and materials science in general. In this paper, we report on the first-ever implementation of an inverse modeling technique on the basis of a genetic optimization scheme in order to extract quantitative information from a P-UPS. We validate the optimization approach for synthetic data, and apply it to experimentally obtained polar scans for annealed aluminum, cold rolled DC-06 steel as well as for carbon fiber reinforced plastics. The investigated samples are plate-like and do not require specific preparation. The inverted material characteristics show good agreement with literature, micro-mechanical models as well as with results obtained through conventional testing procedures." "The pulsed ultrasonic backscatter polar scan and its applications for NDT and material characterization" "Mathias Kersemans, Wim Van Paepegem, Bart Lemmens, Koen Van Den Abeele, Lincy Pyl, Filip Zastavnik, Hugo Sol, Joris Degrieck" "In a conventional ultrasonic polar scan (UPS) experiment, the amplitude or time-of-flight-diffraction (TOFD) values of the transmitted and/or reflected acoustic pulse are recorded for a wide range of incidence angles, in view of gaining knowledge about the elastic properties at the insonified material spot. Here we apply the pulsed UPS technique and investigate the backscattered signal, resulting in the ultrasonic backscatter polar scan (UBPS). It is shown that a UPBS contains a blueprint of geometrically related features of the insonified material spot which can be of particular interest for various industrial applications. We applied the UBPS for (i) the determination of the stacking sequence of a cross-ply composite laminate, (ii) the semi-quantification of a multidirectional microscopic surface corrugation, (iii) the detection of corrosion in an early stage as well as (iv) the detection and the localization of a closed surface breaking crack." "Determination of the orthotropic viscoelastic tensor of composites by means of the pulsed ultrasonic polar scan" "Arvid Martens, Jannes Daemen, Mathias Kersemans, Erik Verboven, Steven Delrue, Wim Van Paepegem, Koen Van Den Abeele" "Currently, advanced new materials such as fibre reinforced plastics (FRP) are being developed for the inclusion in load bearing components of modern industries. In order to select the most suited material for each specific component, accurate knowledge of its mechanical parameters is required. However, the complex nature of these FRPs, primarily expressed by a high degree of anisotropy, makes it difficult to determine their detailed mechanical behaviour. As a means to resolve this difficulty, the Pulsed Ultrasonic Polar Scan (P-UPS) has been developed. In this study, we propose and extend a recently developed two-stage characterization procedure based on amplitude and time-of-flight UPS recordings. This procedure has been tested on both virtual experiments, to show its effectiveness and robustness, as well as on real experimental measurements performed on unidirectional carbon-epoxy composites." "The Pulsed Ultrasonic Backscatter Polar Scan and its Applications for NDT and Material Characterization" "Bart Lemmens, Koen Van Den Abeele" "In a conventional ultrasonic polar scan (UPS) experiment, the amplitude or time-of-flight-diffraction (TOFD) values of the transmitted and/or reflected acoustic pulse are recorded for a wide range of incidence angles, in view of gaining knowledge about the elastic properties at the insonified material spot. Here we apply the pulsed UPS technique and investigate the backscattered signal, resulting in the ultrasonic backscatter polar scan (UBPS). It is shown that a UPBS contains a blueprint of geometrically related features of the insonified material spot which can be of particular interest for various industrial applications. We applied the UBPS for (i) the determination of the stacking sequence of a cross-ply composite laminate, (ii) the semi-quantification of a multidirectional microscopic surface corrugation, (iii) the detection of corrosion in an early stage as well as (iv) the detection and the localization of a closed surface breaking crack. © 2014 Society for Experimental Mechanics." "Identification of the Elastic Properties of Isotropic and Orthotropic Thin-Plate Materials with the Pulsed Ultrasonic Polar Scan" "Arvid Martens, Koen Van Den Abeele" "Already in the early 1980's, it has been conjectured that the pulsed ultrasonic polar scan (P-UPS) provides a unique fingerprint of the underlying mechanical elasticity tensor at the insonified material spot. Until now, that premise has not been thoroughly investigated, nor validated, despite the opportunities this would create for NDT and materials science in general. In this paper, we report on the first-ever implementation of an inverse modeling technique on the basis of a genetic optimization scheme in order to extract quantitative information from a P-UPS. We validate the optimization approach for synthetic data, and apply it to experimentally obtained polar scans for annealed aluminum, cold rolled DC-06 steel as well as for carbon fiber reinforced plastics. The investigated samples are plate-like and do not require specific preparation. The inverted material characteristics show good agreement with literature, micro-mechanical models as well as with results obtained through conventional testing procedures. © 2014 Society for Experimental Mechanics."