SYMPOSIA PAPER Published: 01 January 1982
STP28494S

Indentation Law for Composite Laminates

Source

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.

Author Information

Yang, SH
School of Aeronautics and Astronautics, Purdue University, West Lafayette, Ind.
Sun, CT
School of Aeronautics and Astronautics, Purdue University, West Lafayette, Ind.
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Details
Developed by Committee: D30
Pages: 425–449
DOI: 10.1520/STP28494S
ISBN-EB: 978-0-8031-4849-9
ISBN-13: 978-0-8031-0695-6