Buckling and Post-buckling Behavior if Composite Plates Containing Multiple Delaminations

Abstract

Post-buckling behaviors of rectangular composite plates with multiple circular delaminations are studied experimentally and numerically. The plate is fixed at its loading edges and simply-supported at its side edges considering the CAI test method recommended by SACMA. Multiple circular delaminations are placed at regular intervals in the thickness direction at the plate center. The diameters of the delaminations are increased from the top surface to the bottom surface, which is an idealized pattern of foreign object impact damage of composite laminates as reported by many researchers. A three-dimensional brick element is adopted. The contact problem of the delaminated surfaces is approximately considered by placing spring elements between the double nodes at the upper and lower delamination surfaces, which have no resistance in the tensile direction and high stiffness in the compressive direction. The numerical results are compared with experiment and found to be consistent with the experiment. The effects of the delaminations on the post-buckling behavior of the laminates are discussed parametrically through finite element results.