STP768

    Dynamic Tests of Graphite/Epoxy Composites in Hygrothermal Environments

    Published: Jan 1982


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    Abstract

    The objective of this research is to experimentally determine the effects of hostile, hygrothermal environments on the dynamic behavior of graphite/epoxy composites.

    This objective has been accomplished by performing flexural vibration tests on Narmco 5208/T300 beam specimens of four distinct layups. Dynamic behavior in the dry, room temperature state is contrasted with five other environmental states, including moisture saturation and temperatures up to 93°C (200°F). The properties determined are fundamental natural frequency and damping. The former can be directly related to an effective dynamic modulus in flexure. These properties reflect the consequences of plasticization of the epoxy matrix material in hygrothermal environments. The experimental results indicate that matrix controlled modes of response are the most affected. Generally damping increases and stiffness decreases with increasing hygrothermal conditioning. For most applications, stiffness reductions are the dominant concern; the experimentally determined dynamic reductions are consistent with known static ones.

    Keywords:

    hygrothermal effects, composite materials, structural dynamics, environmental effects


    Author Information:

    Rehfield, LW
    Professor and visiting scholar, School,

    Briley, RP
    Senior engineer, McDonnell Douglas Astronautics,

    Putter, S
    Professor and visiting scholar, School,


    Paper ID: STP29358S

    Committee/Subcommittee: D30.08

    DOI: 10.1520/STP29358S


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