Two-dimensional to three-dimensional global/local finite element analysis of laminated composites in compression

• Main Author: Thompson, Danniella Mellissa Muheim
• Other Authors: Engineering Mechanics
• Format: Others
• Language: en
• Published: Virginia Tech 2014
• Subjects: LD5655.V855 1990.T562; Composite materials; Laminated materials
• Online Access: http://hdl.handle.net/10919/42218; http://scholar.lib.vt.edu/theses/available/etd-04252009-040702/

A two-dimensional to three-dimensional global/local finite element approach was developed, verified, and applied to a laminated composite plate of finite width and length containing a central circular hole. The resulting stress fields for axial compression loads were examined in detail for several symmetric stacking sequences and hole sizes. Verification was based on comparison of the displacements and the stress fields with those accepted trends from previous free edge investigations and a complete three-dimensional finite element solution of the plate. Hole diameters of one, three, and six inches in plates 18 inches long, 12 inches wide, and 0.1 inches thick were considered. The laminates in the compression study included symmetric cross-ply, angle-ply and quasi-isotropic stacking sequences. The entire plate was selected as the global model and analyzed with two-dimensional finite elements. Displacements along a region identified as the global/local interface were applied in a kinematically consistent fashion to independent three-dimensional local models. Local areas of interest in the plate included a portion of the straight free edge near the hole, and the immediate area around the hole. It was found that the global/local interface should not be placed inside or through any region where the stress field exhibits three-dimensional effects. Interlaminar stress results obtained from the global/local analyses compared well with previously reported trends, and some new conclusions about interlaminar stress fields in plates with different laminate orientations and hole sizes are presented for compressive loading. The effectiveness of the global/local procedure in reducing the computational effort required to solve these problems is clearly demonstrated through examination of the computer time required to formulate and solve the linear, static system of equations which result for the global and local analyses to those required for a complete three-dimensional formulation for a cross-ply laminate. The Testbed, which is under continuing development by the Computational Structural Mechanics Group, now the Computational Mechanics Branch, was used throughout this investigation. Specific processors used during the analyses are described in general terms herein. The application of this global/local technique is not limited to this software system, and was developed and described in as general a manner as possible. The methodology developed is thus applicable to other large-scale structural analysis systems. === Master of Science