What is the effect of an antisymmetric laminate?

• A. It introduces coupling between bending and extensional behavior via a nonzero B-matrix.
• B. It eliminates coupling between bending and extension.
• C. It makes the laminate isotropic.
• D. It reduces overall stiffness in all directions.

Answer: (A)

Antisymmetric stacking breaks the symmetry through the thickness, which makes the coupling term in the laminate stiffness nonzero. In classical lamination theory, the in-plane forces and bending moments are related to mid-plane strains and curvatures through the ABD matrices, and a nonzero B-matrix means bending and extensional behavior influence each other. So bending moments can produce in-plane strains and in-plane forces can induce bending. This coupling is the hallmark of an antisymmetric laminate. The other statements don’t fit: symmetry would eliminate this coupling by making the B-matrix zero; antisymmetry does not turn the laminate isotropic (it remains anisotropic due to fiber orientations); and there isn’t a generic claim that stiffness is reduced in all directions—the defining feature is the bending–extensional coupling, not a uniform stiffness decrease.