EU-Project DOTNAC: Terahertz Sensors for Non-Destructive Testing of Aircraft Components

Within the framework of the DOTNAC project, funded by the EU, we developed a terahertz scanner for testing aircraft components together with partners from research and industry. The field of application of the terahertz scanner is the non-destructive testing of fiberglass composite materials and paint layers during production and repair. Defective glued joints, foreign bodies or unwanted air bubbles in the material can be reliably detected with terahertz waves. In addition, the device is able to determine the thickness of the individual paint layers on the aircraft skin.

Research partners from five nations worked on the measuring system , which fits seamlessly into the production processes in aircraft construction. Here, terahertz measurement technology complements established measurement techniques such as thermography or ultrasound - especially in the sense of sensor fusion - and can thus contribute to more efficient and seamless quality control.
 

Summary of Project Results

Terahertz measurement technology is suitable for non-destructive testing of glass fiber reinforced plastics (GFRP) as well as composites with GFRP and honeycomb structure/foam cores. Foreign bodies, voids as well as structural defects can be detected well with the terahertz measurement technique. In the case of carbon fiber-reinforced plastics (CFRP), inspection using terahertz measurement technology is limited to the surface or the applied layers.

The clear advantage of terahertz technology over classic methods such as X-ray, ultrasound and thermography is that, with a single-sided measurement arrangement, defects close to the surface and on the inside as well as on the back can be detected in composite structures with hollow structures (honeycomb core or foam). In addition, the non-contact measurements and the avoidance of radiation protection measures are advantageous when using terahertz technology.
 

Projekt Partners

• Royal Military Academy, Belgium
• Verhaert New Products & Services , Belgium
  
• Support, Belgium
  
• Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau (RPTU), Germany
• Fraunhofer ITWM (formerly IPM), Germany
• CNRS, France
• Centro de Tecnologias Aeronauticas, Spain
• Applus+ LGAI Technological Centre S.A., Spain
• CIMNE, Spain
• Israel Aerospace Industries, Israel