GLARE failure envelopes

In last session there was a discussion on failure envelopes of hybrid
composites. The comments were especially addressed to GLARE. The
separate contributions of the Aluminum and the Fiber Glass plys were
plotted in diagrams on the sigma1-sigma2 space. Prof. Tsai wanted to
demonstrate further GLARE failure envelopes for different ply angles.
The attached figure was taken from Prof. Sung Ha's work. It shows 2
different layups for GLARE laminates: [Al/30/60/Al/60/30/Al] and
[Al/+-45/Al/-+45/Al]. Again, aluminum is the weak link. If GLARE offers
toughness it is hard to prove it by the nature of these envelopes.