Characteristics of thermally-induced transverse cracks in graphite-epoxy composite laminates

The characteristics of thermally-induced transverse cracks in T300/5208 graphite-epoxy cross-ply and quasi-isotropic laminates were investigated both experimentally and analytically. The formation of transverse cracks and the subsequent crack spacing present during cooldown to -250°F (116K) and thermal cycling between 250 and -250°F (116 and 394K) was investigated. The state of stress in the vicinity of a transverse crack and the influence of transverse cracking on the laminate coefficient of thermal expansion (CTE) was predicted using a generalized plane-strain finite element analysis and a modified shear-lag analysis. It is shown that a majority of the cross-ply laminates experienced transverse cracking during the initial cool-down to -250°F whereas the quasi-isotropic laminates remained uncracked. All cross-ply laminates and the [0/±45/90]_s quasi-isotropic laminate exhibited transverse cracking following 20 thermal cycles. The uniformity of crack spacing increased with an increasing number of thermal cycles. The cross-ply laminates exhibited a rather sharp drop in CTE at crack densities less than 50 cracks/in. (19.7 cracks/cm) whereas the quasi-isotropic laminates exhibited a smaller decrease in CTE. The in situ transverse strength of the 90° layers was more than 1.9 times greater than the transverse strength of the unidirectional 90° material for all laminates investigated.

Name thesis:degree_name

M.S.

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Engineering Mechanics

Department dc:contributor.department

Engineering Mechanics

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1983

Author dc:creator

• Adams, Daniel S.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10919/118549

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/118549