1ST-PLY FAILURE OF LAMINATED COMPOSITE PLATES

Composite laminates offer superior load carrying capacity. Reliable ap plication of such structures requires a knowledge of their stress/stra in and failure behavior. Past treatments involved assumptions in both the stress and failure analyses; they become increasingly more difficu lt when the failure of the microstructure constituents is to be includ ed in the continuum analysis of the laminates. Recognizing the convent ional failure criteria used for composite material analyses, this work adopts the first-ply failure criterion by application of a polynomial function and the finite element procedure. The laminates are modeled by the Reissner-Mindlin plate theory that accounts for moderate rotati on. This is because shear effects are more pronounced in composite lam inates whose transverse shear modulus is low relative to the Young's m odulus. Failure loads are obtained for different laminate thicknesses, stacking sequences and aspect ratios and different failure criteria. The results show that predictions made from the maximum stress criteri on are nearly the same as the others, except for those obtained by the Hill criterion.