Accession Number : ADA305655

Title :   Surface Crack Growth in Fiber Composites.

Descriptive Note : Interim rept.,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MATERIALS SCIENCE AND ENGINEERIN G

Personal Author(s) : Im, J. ; Mandell, J. F. ; Wang, S. S. ; McGarry, F. J.

PDF Url : ADA305655

Report Date : SEP 1976

Pagination or Media Count : 147

Abstract : The results of an experimental study of damage extension and failure in glass and graphite/epoxy laminates containing partially through-thickness surface cracks are presented. The laminates studied are divided between those containing four plies, 90/0/0/90, l5/-l5/-l5/l5, and 45/-45/-45/45, and those containing 12-16 plies of the general configurations 0/90, + or - 45, and 0/+ or - 60. Most of the results are for surface cracks of various lengths and several depths. Stable damage extension in laminates containing surface cracks is predominantly delamination between plies, and tends to be much more extensive prior to failure than is the case with through-thickness cracks, resulting in approximately notch-insensitive behavior in most cases. A greater tendency for notch-sensitive behavior is found for 0/90 graphite/ epoxy laminates for which stable damage extension is more limited. The rate of damage extension with increasing applied stress depends upon the composite system and ply configuration as well as the crack length and depth. An approximate semiempirical method is presented for estimating the growth rate of large damage-regions. (MM)

Descriptors :   *FIBER REINFORCED COMPOSITES, *CRACK PROPAGATION, *EPOXY LAMINATES, *GRAPHITE EPOXY COMPOSITES, SURFACE ANALYSIS, DAMAGE ASSESSMENT, GLASS, FRACTURE(MECHANICS), DEFECTS(MATERIALS), DELAMINATION, NOTCH SENSITIVITY.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE