Artur Szewieczek

• Doctor of Engineering
• Managing Director at Hillger NDT

Air-coupled ultrasonic testing is an established alternative to conventional ultrasonic methods for testing of light-weight components in aerospace and automotive industry. Compared to direct coupled contact technique or immersion technique it is less invasive, so that it offers numerous financial incentives. While phased arrays are already an indu...

During production or service life, lightweight components made of fibre-reinforced polymers (FRP) may suffer from different types of defects such as cracks or delamination, which may be detected, amongst others, with the help of ultrasonic lamb waves (LW). The study intends to illustrate the potentials of numerical models to assist the design of LW...

Components made of fibre-reinforced polymers (FRP) may suffer from various types of damages, such as cracks or delamination. In order to monitor the structures’ material condition, non destructive testing (NDT) methods have emerged – among them, the use of ultrasonic waves. Inter alia, research focused on Lamb waves (LW), which offer promising cond...

Seit Jahren stellt die luftgekoppelte Ultraschallprüfung eine etablierte Alternative zur konventionellen Prüfung von Leichtbaukomponenten aus den Bereichen Luft- und Raumfahrt sowie Automotive dar. Im Gegenteil zur flüssigkeitsgekoppelten Prüfung in Kontakt oder im Tauchbecken ist sie weniger invasiv und bietet daher zeitliche und finanzielle Anrei...

The historical development of air-coupled ultrasonic testing is difficult to follow, since it made massive use of developments in other acoustic disciplines. Thus, the driving force for the development of capacitive air-coupled ultrasonic transducers with matched impe-dance (1) was not material testing, but data transmission and distance measuremen...

Elastic waves are often used for experimental or non-destructive testing (NDT) of fiber reinforced composites. For their application, no specific prerequisites, such as electrically conducting materials, a contrast medium, or special surrounding conditions, are required. Due to reflections at any inhomogeneity in a specimen, different kinds of mate...

Guided waves can be used for Structural Health Monitoring (SHM) of modern composites. However, due to the complex wave propagation different scanning and imaging methods are used to achieve a better understanding of wave interaction with complex structures. The acquired data allows advanced applications. The following section presents a method for...

Guided waves, such as Lamb waves, enable a Structural Health Monitoring (SHM) of modern composite structures. However, due to the complex wave propagation different scanning and imaging methods were developed in the past. They enable a better understanding of the wave interaction with complex structures. Beyond video animations of the wave propagat...

A major challenge in the design of sensor networks for Structural Health Monitoring consists in an optimal dimensioning of actuators and sensors in number, position, form and material properties with regard to the specific application. Previous solutions are partly based on a constant or iterative increasing sensor density. Simulations of wave prop...

Methoden der strukturellen Zustandsüberwachung (Structural Health Monitoring, kurz SHM) werden in verschiedenen industriellen Bereichen eingesetzt. Eine wichtige Gruppe von SHM-Verfahren basiert auf geführten Wellen in Platten und plattenähnlichen Strukturen. Hierbei werden auf der Plattenoberfläche applizierte piezoelektrische Wandler zur Anregung...

Purpose – A design of sensor networks for structural health monitoring (SHM) with guided waves poses a hard challenge. Therefore different approaches are possible. A known one is the usage of probability of detection (POD) criteria. Here, areas of potential impact sensitivity are calculated for every sensor which leads to a POD. The number of senso...

Video-imaging is one method of analyzing the shrinkage of resins. For the measurement, a drop of resin is placed near an illumination source and its contour is imaged from the front with a camera. This paper presents a further development, detailed investigation and verification of this technique to analyze the chemical shrinkage of thermally cured...

Structural Health Monitoring with guided waves is a promising technique for online testing of metal or composite panels. However, wave propagation and interaction in complex structures poses a hard challenge for signal validation due to reflections, refractions or mode conversions. In the past different measuring and imaging techniques were develop...

Guided waves like Lamb waves can be excited and received easily by PZT patches attached on plates and plate-like structures. They propagate over large areas with small attenuation and interact with structural discontinuities such as impacts. Therefore, this principle can be used for impact detection and localization. The wave propagation can be ver...

Die zerstörungsfreie Prüfung und Überwachung komplexer Faserverbundstrukturen mit Lamb-Wellen erfordert eine umfassende Berücksichtigung der Probengeometrie, der lokalen, richtungsabhängigen Ausbreitungsgeschwindigkeiten für jeden Wellenmode und der strukturell bedingten Einflüsse auf die Wellenausbreitung im unbeschädigten Bauteil. Nachfolgend wer...

For the development of structural health monitoring (SHM) systems and non-destructive testing methods based on Lamb waves it is very important, to detect and visualize the entire wave field in the structure. This is currently the only way to reliably determine the source of the waves detected at SHM sensors and to trace their propagation paths in c...

Structural Health Monitoring (SHM) based on Lamb waves, a type of ultrasonic guided waves, is a promising technique for in-service inspection of composite structures. This study investigates the attenuation mechanisms of Lamb wave propagation fields. The attenuation of an anisotropic plate is experimental measured with air-coupled ultrasonic scanni...

The present feasibility study demonstrates that impact damage in a sandwich composite can be identified by mapping the interaction of Lamb waves with the damage-induced structural heterogeneity. By inducing mode conversion of the fast Lamb mode, S 0 , into the slow mode, A 0 , the damage site acts as a secondary acoustic source of airborne ultrasou...

Structural Health Monitoring based on Lamb waves, a type of ultrasonic guided waves, is a promising method for in-service inspection of composite structures. In this study, mode selective actuators are developed to excite a particular Lamb wave mode in quasi-isotropic CFRP (carbon fibre-reinforced polymer) plates. Different manufacturing technologi...

The design of a sensor network is required for a successful SHM system applied to complex structures. The wave propagation can be very complex due to reflections, interferences or mode conversions. The knowledge of the wave behaviour is necessary for an optimal sensor configuration. An air-coupled scan technique in conjunction with data storage can...

Structural Health Monitoring (SHM) based on ultrasonic guided waves, so-called Lamb waves, is a promising method for in-service inspection of composite structures without time consuming scanning like conventional ultrasonic techniques. Lamb waves are able to propagate over large distances and can be easily excited and received by a network of piezo...

Lamb waves (LWs) can be easily excited and received by piezoelectric patches, are able to propagate over large distances and interact with defects. Therefore these waves are attractive for active Structural Health Monitoring (SHM) systems. DLR-FA was involved in the EU project AISHA II. The research was focussed on impact detection in a helicopter...

Structural Health Monitoring (SHM) based on Lamb waves, a type of ultrasonic guided waves, is a promising technique for in-service inspection of composite structures. This study presents the development of mode selective actuator and sensor systems based on interdigital transducer (IDT) design. Various parameters such as wavelengths, number and apo...

Honeycomb sandwich components are high tech materials for primary aerospace components; however their impact sensitivity requires a reliable non-destructive testing (NDT). A part of the EU-AISHA II project is the detection of damages caused by impacts in a complex EC 135 helicopter Tailboom structure. An on-board Structural Health Monitoring (SHM)...

Structural Health Monitoring with Lamb Waves in principle allows a detection of defects in complex composite components by mounted PZT sensors. However, the wave behavior is very complex due to dispersive and anisotropic propagation respectively reflections, refractions and mode conversions on local discontinuities like defects. A clear evaluation...

Structural Health Monitoring (SHM) based on ultrasonic guided waves, so-called Lamb waves, is a promising method for in-service inspection of composite structures without time consuming scan-ning like conventional ultrasonic techniques. Lamb waves are able to propagate over large dis-tances and can be easily excited and received by a network of pie...

Structural health monitoring (SHM) with Lamb waves (LWs) principally enables an in-service damage detection of large aircraft components without time-consuming scanning. Piezoelectric elements can be effectively used as senders and receivers for LWs. However, the complex interaction between defects and Lamb waves – especially for composites, the pr...

Structural Health Monitoring (SHM) based on Lamb waves, a type of ultrasonic guided waves, is a promising method for in-service inspection of composite structures. In this study mode selective actuators are developed to excite a particular Lamb wave mode in composite plates. Different ma-nufacturing technologies based on monolithic piezoceramics wi...

Structural Health Monitoring (SHM) based on Lamb waves, a type of ultrasonic guided waves, is a promising method for in-service inspection of composite structures. In this study mode selective actuators are developed to excite a particular Lamb wave mode in composite plates. Different ma-nufacturing technologies based on monolithic piezoceramics wi...

Damage detection based on Structural Health Monitoring (SHM) with Lamb Waves (LWs) enables in principle a testing of components on demand without time consuming scanning. Their excitation and reception is easily possible with piezoelectric transducers (PZTs). LWs can penetrate large areas with a small attenuation and interact with defects. The loca...

„Lamb-Wellen lassen sich einfach mit piezoelektrischen Scheiben anregen und wieder empfangen, sie breiten sich großflächig aus und reagieren mit Fehlstellen, ein zeitaufwändiges Abrastern ist nicht notwendig, und für eine Lokalisierung ist ein entsprechend dichtes Netz an Sensoren und Aktuatoren erforderlich“, so kann man in vielen Literaturstellen...

The paper describes the diverse research activities of the DLR in the topic of Structural Health Monitoring (SHM). SHM based on Lamb waves is a promising method for in-service inspection of aerospace structures without time consuming scanning like conventional ultrasonic techniques. Lamb waves propagate over large distances and can be easily excite...

GFRP and CFRP sandwich structures with honeycomb cores are high performance light weight structures for aerospace applications. Their impact sensitivity requires reliable NDT methods after fabrication and in service. Guided waves are able to propagate over large areas in components with a small attenuation and interact with defects. The DLR part of...

Sandwich components with thin skins of GFRP or CFRP and honeycomb cores are high performance components for aerospace structures with high specific stiffness and strength. However these materials are impact sensitive. The DLR part of the EU-project AISHA II (Aircraft integrated structural health assessment) is focused on a full-scale test of a 3.5...

For defect characterisation and design of a SHM-system, the velocities of Lamb modes, and especially their dispersion behaviour, must be known quantities. Different approaches for the experimental determination of Lamb wave dispersion diagrams for carbon fibre reinforced polymers and other materials are presented. Data acquisition is performed by s...

DLR is involved in the EU-project AISHA II (Aircraft integrated structural health assessment) and is work package leader of the full-scale test. The DLR part is focused on a full-scale test of a 3.5 m long tail-boom oft the EC 135 which consists of a honeycomb sandwich structure with CFRP and GFRP-skins. The unsymmetrical design with different skin...