Size effects in scaled fiber composites under four-point flexure loading

Citation
Dp. Johnson et al., Size effects in scaled fiber composites under four-point flexure loading, AIAA J, 38(6), 2000, pp. 1047-1054
Citations number
15
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Aereospace Engineering
Journal title
AIAA JOURNAL
ISSN journal
0001-1452 → ACNP
Volume
38
Issue
6
Year of publication
2000
Pages
1047 - 1054
Database
ISI
SICI code
0001-1452(200006)38:6<1047:SEISFC>2.0.ZU;2-W
Abstract
The effect of specimen size on the four-point flexural response of ply-leve l and sublaminate-level scaled composites was investigated. Two laminates w ere studied, namely, [+45/-45/+45/-45], and [+45/-45/0/90](x). The material system used was AS4/3502 graphite/epoxy. Enhanced x-ray radiography and ed ge photomicroscopy were used to examine damage development in specimens loa ded to various fractions of their ultimate load. This nondestructive examin ation was coupled with observations of the load/deflection response to try to correlate scaling effects with the damage development in the specimens. Results were compared to previous studies involving tensile scaling effects . It was found that the strength of ply-level scaled laminates decreased as specimen size increased, and that this effect was modeled well using the t ypical fracture mechanics scaling law. Sublaminate-level scaled specimens d id not show a pronounced scaling effect. Although there seemed to be a slig ht decrease in strength with increased specimen size, the effect was small and may not be statistically significant.