2-D to 3-D Global/Local Finite Element Analysis of Cross-Ply Composite Laminates

An example of two-dimensional to three-dimensional global/local finite element analysis of a laminated composite plate with a hole is presented. The "zoom" tech nique of global/local analysis is used, where displacements of the global/local interface from the two-dimensional global model are applied to the edges of the three-dimensional local model. Three different hole diameters, one, three, and six inches, are considered in order to compare the effect of hole size on the three-dimensional stress state around the hole. In addition, three different stacking sequences, [0 _n /90 ₂ ] _s , [90 _n /0 _n ] _s , and [0 _n/2 /90 _n/2 / 0 _n/2 /90 _n/2 ] _s , are analyzed for the six inch hole case in order to study the effect of stacking sequence. All laminates are 0.1 inch thick, with planar dimensions of 18 by 12 inches, loaded by uniform uniaxial compressive displacements of the ends. The existence of a "critical" hole size, where the interlaminar stresses are maximum, is indicated. Dispersion of plies at the same angle, as opposed to clustering, is found to reduce the magnitude of some interlaminar stress components and increase others. The global/local analysis tech nique is found to yield reasonably economical solutions to problems which would be pro hibitive to analyze completely using three-dimensional finite element analysis alone.