Development of Reference Test CFRP Specimens for the Standardisation of Active Thermography with Flash Excitation

  • With increasing use of carbon fibre reinforced polymers (CFRP) in civil aviation, the need for nondestructive testing (NDT) techniques has gained significance. One of the very promising methods is active thermography with flashlight excitation (flash thermography). Already exploited to detect faults in CFRP laminates it is yet not recognized as test method for the very reason an international user standard is missing. The authors will present the results of a project involving the development of a testing standard for flash thermography. In addition to the standardization of the selection of appropriate equipment and procedures for testing and data analysis, the new standard will provide suitable reference test specimens for several materials, including CFRP. These test specimens should enable qualification of the equipment as well as the validation of flash thermography. For this purpose, specimens of CFRP prepregs containing various typical flaws have been manufactured. These flawsWith increasing use of carbon fibre reinforced polymers (CFRP) in civil aviation, the need for nondestructive testing (NDT) techniques has gained significance. One of the very promising methods is active thermography with flashlight excitation (flash thermography). Already exploited to detect faults in CFRP laminates it is yet not recognized as test method for the very reason an international user standard is missing. The authors will present the results of a project involving the development of a testing standard for flash thermography. In addition to the standardization of the selection of appropriate equipment and procedures for testing and data analysis, the new standard will provide suitable reference test specimens for several materials, including CFRP. These test specimens should enable qualification of the equipment as well as the validation of flash thermography. For this purpose, specimens of CFRP prepregs containing various typical flaws have been manufactured. These flaws are similar to those which occur in operation, for example as a result of an impact. The impact specimens have been constructed and damaged according to DIN 65561 with energies ranging from 4 to 24 J. Other specimens contain flaws similar to those which are caused by production processes, for example deviating fiber direction. Systematic measurements and new methods of analysis enhanced the knowledge about best experimental set ups for detecting different flaws. Furthermore the accuracy of the defect size examination with flash thermography had to be judged. For this purpose specimens with well known artificial defects have been investigated. These specimens have been performed as stepbars with inclusions of double layered Polytetrafluorethylen (PTFE) foil platelets in squares sized from 2 to 20 mm². The steps ensure laminate coverings of the defects from 0.5 to 5.5 mm². In combination with new developed data analysis, the measurements on the stepbars demonstrate that this type of specimens might conceivable for adjustment of flash thermography set ups and should be recommended for the future standard. Some of the experimental findings are still debated and further research is needed in order to establish a well prepared user standard for flash thermography. Since the project will end at the beginning of 2013 these questions will be explored, whereby the transferring of conclusions to on-site applications is of particular interest.zeige mehrzeige weniger

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  • 2012-11-15 Development of Reference Test CFRP Specimens for the Standardization of Active Thermography with Flash Excitation.pdf
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Metadaten
Autor*innen:Mercedes Reischel
Koautor*innen:Philipp Myrach, Christiane MaierhoferORCiD
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Deutsch
Titel des übergeordneten Werkes (Deutsch):4th International Symposium on NDT in Aerospace
Jahr der Erstveröffentlichung:2012
Veranstaltung:4th International Symposium on NDT in Aerospace
Veranstaltungsort:Augsburg, Germany
Beginndatum der Veranstaltung:2012-11-13
Enddatum der Veranstaltung:2012-11-15
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:20.02.2016
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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