Fg. Yuan et Mc. Selek, TRANSVERSE CRACKING AND STIFFNESS REDUCTION IN COMPOSITE LAMINATES, Journal of reinforced plastics and composites, 12(9), 1993, pp. 987-1015
A study of transverse cracking mechanism in composite laminates is pre
sented using a singular hybrid finite element model. The model provide
s the global structural response as well as the precise local crack-ti
p stress fields. An elasticity basis for the problem is established by
employing Lekhnitskii's complex variable potentials and method of eig
enfunction expansion. Stress singularities associated with the transve
rse crack are obtained by decomposing the deformation into the symmetr
ic and antisymmetric modes and proper boundary conditions. A singular
hybrid element is thereby formulated based on the variational principl
e of a modified hybrid functional to incorporate local crack singulari
ties. Axial stiffness reduction due to transverse cracking is studied.
Numerical examples are illustrated for [0n/90m]s and [theta(n)/90m]s
composite laminates with glass/epoxy and graphite/epoxy. The results a
re shown to be in very good agreement with the existing experimental d
ata. Comparison with simple shear lag analysis is also given. The effe
cts of stress intensity factors and strain energy density on the incre
ase of crack density are analyzed. The results reveal that the paramet
ers approach definite limits when crack densities are saturated, an ev
idence of the existence of Characteristic Damage State (CDS).