Nl. Breivik et al., COMPRESSION OF LAMINATED COMPOSITE BEAMS WITH INITIAL DAMAGE, Journal of reinforced plastics and composites, 12(7), 1993, pp. 813-824
Compression testing is conducted for specimens with well-documented in
itial damage states obtained from three-point bend testing. Strengths
and failure modes are determined for specimens with four quasi-isotrop
ic stacking sequences and two thicknesses. Initial damage prior to com
pression testing is divided into three classifications based on the ex
tent and location of the damage. These are (1) specimens with short de
laminations distributed evenly through the specimen thickness, (2) spe
cimens with few long delaminations, and (3) specimens with local fiber
damage in the surface plies under the three-point bend contact point.
Specimens without initial damage are also tested in order to determin
e the effects of the initial damage on the final compression strength
and failure modes. It was found that specimens with short multiple del
aminations experienced the greatest reduction in compression strength
compared to the undamaged specimens. All of the sublaminates formed by
the delaminations failed at the same time with no indication of subla
minate buckling. Individual sublaminate buckling was observed for long
er, isolated delaminations near the surface of the laminate. Single de
laminations far from the specimen surface had little effect on the fin
al compression strength, with moderate strength reduction observed for
specimens with localized surface ply damage.