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Non-Destructive Inspection

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					                                           Nationaal Lucht- en Ruimtevaartlaboratorium
                                                      National Aerospace Laboratory NLR



     Non-Destructive Inspection




     Non-destructive inspection (NDI) is the assessment of the quality of a material or struc-
     ture without impairing its further use.
     In general the main emphasis is on the detection of defects:
        In metal: cracks, corrosion, inclusions
        In composites: delaminations, matrix cracks, fibre fracture

     NDI can also include the assessment of:
       Geometrical deviations (thickness, coating)
       Material structure/composition
       Material properties (conductivity, hardness)


Research areas
     NLR provides assistance and carries out research under contract to airlines, air forces and
     aircraft manufacturers, in addition to carrying out a basic research programme. Activities
     of NLR include:
        Evaluation and development of new NDI techniques
        Investigating the reliability of NDI
        NDI of composite materials
        NDI of ageing aircraft
        Level III assistance
        Training/examination/certification of NDI personnel
      Non-Destructive Inspection at NLR — March 2007




Equipment for NDI
      Equipment available at NLR includes:
        Ultrasonic C-scan equipment, featuring:
        – immersion and squirter inspection mode
        – inspection of rectangular and cylindrical specimens (maximum specimen
           dimensions 900 x 2400 mm, maximum diameter 900 mm)
        – advanced data acquisition and analysis system
        Ultrasonic phased array equipment
        Ultrasonic portable thickness gauges
        Eddy current dual-frequency equipment + rotor C-scan application
        Equipment for penetrant and magnetic inspection
        Fokker Bondtester


Example of ultrasonic inspection




      In-situ ultrasonic inspection during NH-90 tail fatigue test


Ultrasonic phased array equipment




      Omniscan™ PA of Olympus NDT with a 128-element phased array transducer
      Non-Destructive Inspection at NLR — March 2007




Example of ultrasonic inspection




      Ultrasonic C-scan of impact damage in a composite laminate, using a
      5 MHz focused transducer


Example of penetrant inspection




      Cross-section of a composite laminate with impact damage:
      laminate damage detected by fluorescent penetrant inspection
      (arrow indicates location of impact)




                    Structural Health Monitoring (SHM)
      SHM techniques are special NDI techniques that are employed in-service to assess the
      structural health of systems such as aircraft. The techniques are aimed at the detection,
      localisation and characterisation of structural damage (environmental, accidental).
      In contrast to conventional NDI techniques that are operated off-board during scheduled
      maintenance on the ground, SHM techniques are part of on-board systems (centralised
      or distributed) with low-profile sensors that are permanently attached to the structure
      (in-situ). The SHM techniques can be operated on-line during the flight or off-line on the
      ground.


Equipment for SHM
        Acoustic emission equipment
        Eddy current array equipment
        Comparative Vacuum Monitoring (CVM) system
                                           Non-Destructive Inspection at NLR — March 2007




                                  Example of acoustic emission (AE) measurement



                                                                                                      rise time

                                                                                                                  peak amplitude

                                                                                          rise time
                                                                                          slope                               ringdown counts
                                                                                                                                   n = 12
                                                                                                                                          threshold




                                                                                                             event duration

                                                                                               waveform characteristics of an AE event




                                                                                         Acoustic emission for the detection of cure related
                                                                                         defects in thick RTM products


                                  Example of Comparative Vacuum Monitoring (CVM) measurement




                                           CVM measurement on a Glare specimen for the detection of fatigue cracks


           For more information:
           NLR Aerospace Vehicles Division;              NLR Amsterdam                                        NLR Noordoostpolder
           Structures Testing & Evaluation               Anthony Fokkerweg 2, 1059 CM Amsterdam               Voorsterweg 31, 8316 PR Marknesse
           J.H. Heida             D.J. Platenkamp        P.O. Box 90502, 1006 BM Amsterdam                    P.O. Box 153, 8300 AD Emmeloord
           E-mail heida@nlr.nl – platenk@nlr.nl          Telephone +31 20 511 31 13                           Telephone +31 527 24 84 44
F 107-06




           Telephone +31 527 248283 / 248217             Fax +31 20 511 32 10                                 Fax +31 527 24 82 10
           Web site http://www.nlr.nl                    The Netherlands                                      The Netherlands

				
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posted:11/17/2011
language:Dutch
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