Volume 21, Issue 5 (September 1993)

    Characterization of Defects in Graphite Fiber Based Composite Structures Using the Acoustic Impact Technique (AIT)

    (Received 18 May 1992; accepted 23 March 1993)

    CODEN: JTEOAD

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    Abstract

    Acoustic Impact Technique (AIT), commonly known as “coin-tapping,” has been applied by previous investigators as a nondestructive evaluation technique to study disbonds in composite honeycomb structures. The experimental configuration adopted by previous investigators was somewhat restricted. In this study, a different approach to AIT is developed. This was done to overcome the experimental constraints encountered in the previous approaches. This paper presents experimental results obtained in the evaluation of defects commonly found in graphite based composite structures, such as delamination, fiber breakage, and misaligned fibers. The experimental approach adopted in this work has two main features. Primarily, the force-time history of the specimen's response to a low magnitude input pulse in different regions of the specimen is compared. Secondly, an Acoustic Emission (AE) wide band sensor was used in conjunction with the conventional acoustic impact technique. The combination of the AE sensor and AIT enabled the study of the material interaction with stress waves generated in the vicinity of the tapped region. Gross defects such as delaminations were identified through the change in the pulse width of the force input, while defects such as fiber breakage and misaligned fibers were successfully identified using AIT in conjunction with AE.


    Author Information:

    Raju, PK
    Associate professor and graduate student, Auburn University, Auburn, AL

    Patel, JR
    Site manager, Refrigerant Recovery Corp of America, Sacramento, CA

    Vaidya, UK
    Associate professor and graduate student, Auburn University, Auburn, AL


    Stock #: JTE11782J

    ISSN: 0090-3973

    DOI: 10.1520/JTE11782J

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    Author
    Title Characterization of Defects in Graphite Fiber Based Composite Structures Using the Acoustic Impact Technique (AIT)
    Symposium , 0000-00-00
    Committee E28