scholarly journals Terahertz based non-destructive testing (NDT)

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Dirk Nüßler ◽  
Joachim Jonuscheit

AbstractEstablished methods based on X-rays, ultrasound, thermography, eddy current, and optics are very effective in fault detection and structural analysis. However, these methods are limited for some applications, for example, the non-destructive testing of fiber-reinforced plastics, foams, and sandwich or hollow structures. In these cases, terahertz technology offers an innovative method to overcome these limitations. Tremendous advances have been made in this new technology in terms of their industrialization in recent years. This paper presents techniques for use in industrial applications.

Author(s):  
W Steinchen ◽  
L Yang ◽  
G Kupfer ◽  
P Mäckel

Digital shearography, a laser interferometry technique in conjunction with the digital imaging processing, has the potential for identifying defects both in small- and large-scale structures. This paper will focus on the recent development of digital shearography for non-destructive testing (NDT). With the improvement of the measuring methods and the development of a small and mobile measuring device in conjunction with a user-guided program, Shearwin, this laser inspection technique can be used easily in the environment of fieldwork. A few examples show its application in the aerospace industry for NDT of composites, e.g. GLARE panel, honeycomb structure and glass (or carbon)-fibre-reinforced plastics, etc.


2011 ◽  
Vol 61 ◽  
pp. 79-83 ◽  
Author(s):  
Salim Bennoud ◽  
Zergoug Mourad

All aircraft whatever they are; are regularly audited. These controls are mainly visual and external; other controls such as "major inspection" or "general revisions” are more extensive and require the dismantling of certain parts of the aircraft. Some parts of the aircraft remain inaccessible and are therefore more difficult to inspect (compressor, combustion chamber, and turbine). The means of detection must ensure controls either during initial construction, or at the time of exploitation of all the parts. The Non destructive testing (NDT) gathers the most widespread methods for detecting defects of a part or review the integrity of a structure. The aim of this work is to present the different (NDT) techniques and to explore their limits, taking into account the difficulties presented at the level of the hot part of a turbojet, in order to propose one or more effective means, non subjective and less expensive for the detection and the control of cracks in the hot section of a turbojet. To achieve our goal, we followed the following steps: - Acquire technical, scientific and practical basis of magnetic fields, electrical and electromagnetic, related to industrial applications primarily to electromagnetic NDT techniques. - Apply a scientific approach integrating fundamental knowledge of synthetic and pragmatic manner so as to control the implementation of NDT techniques to establish a synthesis in order to comparing between the use of different methods. - To review recent developments concerning the standard techniques and their foreseeable development: eddy current, ultrasonic guided waves ..., and the possibility of the implication of new techniques.


Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 554 ◽  
Author(s):  
Mathias Kersemans ◽  
Erik Verboven ◽  
Joost Segers ◽  
Saeid Hedayatrasa ◽  
Wim Van Paepegem

Different non-destructive testing techniques have been evaluated for detecting and assessing damage in carbon fiber reinforced plastics: (i) ultrasonic C-scan, (ii) local defect resonance of front/back surface and (iii) lock-in infrared thermography in reflection. Both artificial defects (flat bottom holes and inserts) and impact damage (barely visible impact damage) have been considered. The ultrasonic C-scans in reflection shows good performance in detecting the defects and in assessing actual defect parameters (e.g., size and depth), but it requires long scanning procedures and water coupling. The local defect resonance technique shows acceptable defect detectability, but has difficulty in extracting actual defect parameters without a priori knowledge. The thermographic inspection is by far the fastest technique, and shows good detectability of shallow defects (depth < 2 mm). Lateral sizing of shallow damage is also possible. The inspection of deeper defects (depth > 3–4 mm) in reflection is problematic and requires advanced post-processing approaches in order to improve the defect contrast to detectable limits.


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