Progressive failure analysis of a composite shell

The objective of this research is to determine the physical response including material failure of a thin, curved composite panel designed to resist transverse loading. The cause of the material failure, in the form of fiber, matrix and/or delamination failure, will be determined through failure criterion based on nonlinear movement using a finite element analysis technique. The finite element analysis technique known as the simplified large displacement/rotation (SLR) theory allows for large displacements but assumes small to moderate rotations (A.N. Palazotto, S.T. Dennis, Nonlinear Analysis of Shell Structures, American Institute of Aeronautics and Astronautics, Inc., Washington, DC, 1992). Third-order shell kinematics, defined relative to the shell midsurface, allow for the characterization of in-plane and transverse shear effects, while neglecting the direct transverse effects. Data generated using the SLR theory both with and without the addition of progressive failure criteria, will be compared with previously published experimental data, noting where the SLR theory diverges from the experimental results. The inclusion of the Hashin failure criterion will provide a more realistic representation of the total physical response of the shell (Z. Hashin, J. Appl. Mech. 47 (1980) 329¯334). The criterion will investigate the shell, from initial loading, to further progressive composite failures. As the composite shell fails, the constitutive relations, or shell stiffness will be reduced. Results of the analytic comparison with the experimental data indicate that the SLR theory overpredicts the stiffness of the shell whether considering or not considering failure criteria. Results generated for the case incorporating a progressive failure criterion are closer to the experimental data because of the reduced stiffness due to failure as the deflection increases