13:29 Jan-26-2009 Denny Meyer R & D University of applied sciences Magdeburg-Stendal, Germany, Joined Jan 2009 4
NDE on GFRP
For a project I need some informations about the capability of NDE methods on GFRP like ultrasonic, radiography, thermography or accoustic methods.
- Which kind of defects can be detected with these methods?
- What are the detection limits of these methods at GFRP?
- Is there any method appropriated for the NDE on thick GFRP specimens like rotorblades?
This is a huge topic. If you use the "Search & Archive" facility on the NDT.net forum website and search under "wind turbine" you will find a number of papers that cover a range of NDT techniques and their capability for the inspection of GFRP rotor blades.
Non Contact method - visit www.ultrandroup.com. You can have more details
Contact Method: log on to www.force.dk and www.sonatest.com. You will get plenty of application details from thier websites
Radiography Method: log on to www.vidisco.com for details.
This is a huge topic and in order to provide a concrete answer within a few lines we will need more info. For instance the type of defects in composites materials strongly depends on the manufacturing process (e.g. different defects are expected in hand lay up GFRP vs. high quality GFRPs manufactured in Autoclave). As in most of the cases in NDE a single method will not detect all different types of defects,
In the case of Thick Composites and rotor blades different methods might be used depending on the defects of interest. For instance:
- Acousto-Ultrasonic or Oblique angle Acousto Ultrasonic might be used to detect delaminations and planar flaws (for further info visit NDT Automation relevant web page at
- Traditional ultrasonic might be used as well, although the penetration max inspection depth might be limited. Olympus offer the so called High Power, High Penetration gauges such as the 25HP ( for further info visit http://www.olympus-ims.com/en/25hp-plus ) which with low frequency UT sensors might do the job.
- Acoustic Emission has been extensively used in testing of Rotor Blades. The method is applied either during controlled loading or during normal operation of the blades and proved to be sensitive as an early warning technique. For further info on NDT net note papers such as http://www.ndt.net/article/wcndt00/papers/idn553/idn553.htm and http://www.ndt.net/v07n09.htm , An extensive list of papers and summary of AEGIS R&D project can be found at http://www.eru.rl.ac.uk/AEGIS/aegis.htm
- As previously pointed out, thermography is also used during testing of Rotor blades and a comparative study between thermography and AE can be found in AEGIS web page.
Should you need additional info please feel free to contact me directly.
I have worked on some research into methods for GFRP NDE, particularly thermal methods and for wind turbine blades. I suggest you look for reports and studies from who I then worked for
at Rutherford Appleton Lab, UK (http://www.eru.rl.ac.uk/projects_wind.html#I_Proj1)
Dr Dutton' s opinion on what works would be worth attention - ask him.