STP787: Indentation Law for Composite Laminates

    Yang, SH
    Graduate Research Assistant and Professer, School of Aeronautics and Astronautics, Purdue University, West Lafayette, Ind.

    Sun, CT
    Graduate Research Assistant and Professer, School of Aeronautics and Astronautics, Purdue University, West Lafayette, Ind.

    Pages: 25    Published: Jan 1982


    Abstract

    Static indentation tests have been conducted on glass/epoxy and graphite/epoxy composite laminates with steel balls as the indentor. Beam specimens clamped at various spans were used for the tests. Loading, unloading, and reloading data were obtained and fitted into power laws. It was found that the contact behavior is not appreciably affected by the span. Both loading and reloading curves seem to follow the 1.5 power law, and the unloading curves are described quite well by a 2.5 power law.

    An interesting finding is a critical indentation (αcr) that can be used to predict permanent indentations in unloading. Since αcr only depends on composite material properties, only the loading and an unloading curve are needed to establish the complete loading/unloading behavior. According to the present model, no reloading tests are necessary for deriving the reloading law.

    Keywords:

    composite laminates, indentation test, contact law, loading, unloading, reloading


    Paper ID: STP28494S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP28494S


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