Effect of different size multiple delaminations on compressive behavior of composite laminates

Abstract

Effects of multiple delaminations of different sizes on the compressive behavior of rectangular composite laminates are studied using both shell and brick elements. Embedded delaminations exist at a regular interval in the thickness direction, but their diameters change linearly with the depth from the surface. The loading edges are fixed and the side edges simply-supported, following the SACMA CAI test standard. The brick elements are used to model the delaminated portions and surrounding portion and the shell elements to model the undelaminated portion. The energy release rate can bc well estimated, because the three dimensional brick elements are used in the neighborhood of the crack front. The fracture due to instability of the delamination is discussed using distributions of energy release rate along the delamination edges. Though the change of the sizes of delaminations in the thickness direction significantly influences on the compressive behavior of the delaminated plate effects just after the buckling, the basic behavior is similar to that of the plate with equal diameter multiple delaminations. The postbuckling behavior consists of three stages: initial local instability of the delaminated portion, global deformation of symmetric shape and global deformation of antisymmetric shape. Keyword : Composite, Buckling, Postbuckling, Multiple delaminations, Energy release rate, Finite element analysis, CAL