Effects of moisture on matrix cracking in a cryo-cycled cross-ply laminate

Abstract

This work was motivated by previous cryogenic-cycling experiments using liquid nitrogen and associated analysis of a balanced and symmetric cross ply laminate with polished edges made from IM7 fibers and CYCOM 5250-4 bismaleimide matrix. Moisture effects were studied both experimentally and analytically in an attempt to explain differences in crack occurrences between inner and outer plies and between otherwise nearly identical experiments. It was shown that moisture locally diffused into a surface layer has a three-dimensional effect on the laminate stress distribution near the edges where cracks initiate. These effects are strongly ply dependent and help explain ply-to-ply variations in crack densities observed in experiments. © The Author(s) 2011 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.