Accession Number : ADA306043

Title :   Indentation Law for Composite Laminates.

Descriptive Note : Topical rept.,

Corporate Author : PURDUE UNIV LAFAYETTE IN COMPOSITE MATERIALS LAB

Personal Author(s) : Yang, S. H. ; Sun, C. T.

PDF Url : ADA306043

Report Date : 31 JUL 1981

Pagination or Media Count : 57

Abstract : Static indentation tests are described for 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. Results show that (1) contact behavior is not appreciably affected by the span; (2) loading and reloading curves seem to follow the 1.5 power law; and (3) unloading curves are described quite well by a 2.5 power law. In addition values were determined for the critical indentation, alpha sub cr, which can be used to predict permanent indentations in unloading. Since alpha sub cr only depends on composite material properties, only the loading and an unloading curve are needed to establish the complete loading-unloading-reloading behavior. (MM)

Descriptors :   *LAMINATES, *IMPACT STRENGTH, *GRAPHITE EPOXY COMPOSITES, *GLASS REINFORCED PLASTICS, COMPOSITE MATERIALS, DEFORMATION, MODULUS OF ELASTICITY, LEAST SQUARES METHOD, FAILURE(MECHANICS), STATIC TESTS, CYCLIC LOADS, POISSON RATIO, DISTRIBUTION CURVES.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE