On the instability of multiple annular delaminations of axisymmetric laminates with arbitrary boundary conditions subjected to transverse load

Abstract Herein, the damage problem of quasi-isotropic composite laminates subjected to a quasi-static transverse load has been studied analytically. The damage was modeled as multiple equal-sized annular delaminations of equal-interval in the thickness direction without any opening during transverse loading. This simplified damage shape was adopted according to the typical damage morphology of impact-tested laminates. Closed-form expressions of the responses, such as a deflection and an energy release rate, were developed in terms of the applied force, dimensions of the plates, and damage under arbitrary boundary conditions based on the Mindlin plate theory. Though their applicability is limited owing to an assumption of linearity, the closed-form expressions provide fundamental information, particularly at the initiation and early growth of the damage, on the effects of the boundary conditions, dimensions, fundamental material properties, and ply thickness of the composite laminates.