Large delaminations could be induced by low velocity impact of laminated composites. The local buckling behavior of laminated composite containing large delaminations is not as well understood as that with small delaminations. This paper presents the analytical modeling of the local buckling behavior of laminated composite containing a large elliptic delamination embedded near the surface and rest partially on Winkler foundation. A formula estimating the elastic modulus of the Winkler foundation is also proposed based on an elastic model. It is shown that the buckled shape predicted by the proposed model is similar to the truly assumed one. A small portion between the delamination tip and the inward portion, which shows slight deflections outward, is found to exist. The first buckling mode takes place at higher and higher mode shape with more flexible sub-laminate, larger delamination, and stiffer Winkler foundation. Increasing the elastic modulus of the interply matrix layer within a certain extent, decreasing the size of the delamination, and enhancing the stiffness of the sub-laminate are effective in reinforcing the local buckling resistance.
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