Buckling of a circular sublaminate in a composite laminate

The buckling of a circular delaminate near the surface of a thick laminate is studied in this paper. The thickness of the sublaminate is assumed to be small compared with the total laminate thickness. The transverse deflection including a bending-torsion and shear-extension coupling terms is assumed and the Rayleigh-Ritz method is used for the analysis. Effects of the base laminate Poisson's ratio, radius of delaminate, and layup on buckling strains are discussed. The results show that (1) the buckling strains decrease when the radius of sublaminate increases and are independent of the Poisson's ratio; (2) the buckling strains increase when the base laminate Poisson's ratio increases; (3) if there is tension buckling strain is determined by the Poisson's ratio only.