Structural Analysis Methods and Elastic Property Determination for Laminated Composites.

Recent applications of laminated composites to ship structural components have highlighted both the analytical complexities involved and the need for providing the structural designer and analyst with appropriate laminate analysis methods. To this end, three types of analytical methods, traditionalloy applied to metallic ship structural components, have been extended to the analysis of laminated composites procedures for their implementation are discussed. These methods include a strength-of-materials techniques for laminated beam and column members, b classical analysis methods for the bending, buckling, and vibration of laminated plating, and c finite-element techniques for either individual laminated components or more complex hybrid structures. Finite-element approaches are discussed for investigating both the in-plane stresses in the individual layers of a laminate and the interlaminar shear and normal stresses which frequently govern near discontinuities in laminate cross sections. The use of these three analysis techniques necessitates that laminated composite components be analyzed as nonlaminated components having equivalent stiffness during in-plane axial and shear and out-of-plane bending responses. Three kinds of equivalent elastic properties for laminates are defined, and methods are presented for calculating each of them. Since these computational procedures may be quite lengthy for laminates with more than a few layers, a computer program is referenced which automates the procedures.